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'''Scientific method''' is the way that scientists investigate [[phenomenon|phenomena]] and acquire new [[knowledge]]. It is based on [[observable]], [[empirical]], measurable evidence, and subject to [[deductive reasoning|laws]] of [[inductive reasoning|reasoning]].
The '''scientific method''' is how scientists investigate [[phenomenon|phenomena]] and acquire new [[knowledge]]. It is based on [[observable]], [[empirical]], measurable evidence. Scientists propose [[hypothesis|hypotheses]] to explain [[phenomena]], and formulat. [[Theory#Science|theories]] that encompass whole domains of inquiry and bind hypotheses together into logically coherent wholes. They design [[experiment]]al [[research|studies]] to elaborate theories and test hypotheses.  
Scientists propose [[hypothesis|hypotheses]] to explain [[phenomena]], and design [[experiment]]al [[research|studies]] to test these. [[Theory#Science|Theories]] that encompass whole domains of inquiry bind hypotheses together into logically coherent wholes. This aids in formulating new hypotheses, as well as in placing groups of hypotheses into a broader context.  
 
==Elements of scientific method==
<blockquote>  
<blockquote>  
''"Science is a way of thinking much more than it is a body of knowledge." '' ([[Carl Sagan]]<ref>Sagan C. The fine art of baloney detection. Parade Magazine, p 12­13, Feb 1, 1987.</ref>).
''"Science is a way of thinking much more than it is a body of knowledge." '' ([[Carl Sagan]]<ref>Sagan C. The fine art of baloney detection. Parade Magazine, p 12­13, Feb 1, 1987.</ref>).
</blockquote>
<blockquote>
''". . .science consists in grouping facts so that general laws or conclusions may be drawn from them."'' ([[Charles Darwin]])
</blockquote>
</blockquote>


The scientific method involves:
==Elements of scientific method==
* '''Observation'''.  A constant feature of scientific inquiry.
According to [[Charles Darwin]] ,
* '''Description'''.  Information must be reliable, i.e., replicable (repeatable) as well as valid (relevant to the inquiry).
:''". . .science consists in grouping facts so that general laws or conclusions may be drawn from them."''  
* '''Prediction'''.  Information must be valid for observations past, present, and future of given phenomena, i.e., purported "one shot" phenomena do not give rise to the capability to predict, nor to the ability to repeat an experiment.
* '''Control'''. Actively and fairly sampling the range of ''possible'' occurrences, whenever possible and proper, as opposed to the passive acceptance of opportunistic data, is the best way to control or counterbalance the risk of empirical bias.
* '''Falsifiability''',  ''All hypotheses and theories are in principle subject to disproof''.
* '''Causal explanation'''.  Many scientists and theorists on scientific method argue that concepts of causality are not obligatory to science, but are in fact well-defined only under particular, admittedly widespread conditions. Under these conditions the following requirements are generally regarded as important to scientific understanding:
:* '''Identification of causes'''
:* '''Covariation of events'''.  The hypothesized causes must [[correlate]] with observed effects.
:* '''Time-order relationship'''.  The hypothesized causes must precede the observed effects in time.


The essential elements of a scientific method are [[iteration]]s, [[recursion]]s, [[interleaving]]s, and [[Partially ordered set|orderings]] of the following:
This simple account begs many fundamental questions. What do we mean by ‘facts’?  How much can we trust our senses to enable us to believe that what we see is true?  How exactly do scientists ‘group’ facts?  How do they select which facts to pay attention to, and is it even possible to do this in an objective way? And having done this, how exactly do they go about drawing any broader conclusions from the facts that they assemble? How can we know ‘’more’’ than we observe directly?
*[[#Characterizations|Characterizations]] (Quantifications, observations, and measurements)
*[[#Hypothesis development|Hypotheses]] (theoretical, hypothetical [[explanation]]s of observations and measurements)
*[[#Predictions from the hypotheses|Predictions]] ([[reasoning]] including [[logic]]al [[deduction]] from [[hypotheses]] and [[theories]])
*[[#Experiments|Experiments]] ([[Experiment|test]]s of all of the above)


The element of [[observation]] includes both unconditioned observations (before any theory) as well as the observation of the experiment and its results. The element of [[experimental design]] must consider the elements of hypothesis development, prediction, and the effects and limits of observation because all of these elements are typically necessary for a valid experiment.
We live in a world that is not directly understandable. We sometimes disagree about the ‘[[fact]]s’ we see around us, and some things in the world are at odds with our understanding. What we call the “scientific method” is an account of how scientists attempt to reach agreement and understanding, to provide explanations that will be consistent with the world and will withstand critical logical and experimental scrutiny. A "perfect" scientific method might work in such a way that its [[rationality|rational]] application would always result in agreement and understanding; a perfect method would arguably be [[algorithm|algorithmic]], and not leave any room for rational agents to disagree. [[Logical positivism|Logical Positivist]], [[empiricism|empiricist]], [[falsifiability|falsificationist]], and other theories have claimed to give a definitive account of the logic of science, but each has been criticised.  


[[Imre Lakatos]] and [[Thomas Kuhn]] had done extensive work on the "theory laden" character of observation. Kuhn (1961) maintained that the scientist generally has a theory in mind before designing and undertaking experiments so as to make empirical observations, and that the "route from theory to measurement can almost never be travelled backward". This perspective implies that the way in which theory is tested is dictated by the nature of the theory itself which led Kuhn (1961, p. 166) to argue that "once it has been adopted by a profession ... no theory is recognized to be testable by any quantitative tests that it has not already passed".
The success of science, as measured by the technological achievements that have progressively changed our world, have led many to the conclusion that this must reflect the success of rules that scientists follow in their research. However, not all philosophers accept this conclusion; notably, the philosopher  Paul [[Feyerabend]] denied that science is genuinely a methodological process. In his book ''[[Against Method]]'' he argued that scientific progress is ''not'' the result of applying any particular rules. Instead, he concluded almost that "anything goes", in that for any particular ‘rule’ there are abundant examples of successful science that have proceeded in a way that seems to contradict it. <ref> [[Paul Feyerabend|Feyerabend PK]] (1975) ''Against Method, Outline of an Anarchistic Theory of Knowledge'' Reprinted, Verso, London, UK, 1978</ref> To Feyeraband, there is no fundamental difference between science and other areas of human activity characterised by reasoned thought. A similar sentiment was expressed by  [[T.H. Huxley]] in 1863:  “The method of scientific investigation is nothing but the expression of the necessary mode or working of the human mind. It is simply the mode at which all phenomena are reasoned about, rendered precise and exact.”
Nevertheless, in the Daubert v. Merrell Dow Pharmaceuticals, Inc. [509 U.S. 579 (1993)] decision, the U.S. Supreme Court accorded a legal status to ‘The Scientific Method ‘, in ruling that “… in order to qualify as ’scientific knowledge’ an inference or assertion must be derived by the scientific method. Proposed testimony must be supported by appropriate validation - i.e., ‘good grounds,’ based on what is known.” The Court also stated that “A new theory or explanation must generally survive a period of testing, review, and refinement before achieving scientific acceptance. This process does not merely reflect the scientific method, it is the scientific method.”


Each element of scientific method is subject to [[peer review]]. These activities do not describe all that scientists do ([[#Dimensions of practice|see below]]) but apply mostly to experimental sciences (e.g., physics, chemistry).  
==Hypotheses and theories==
Hypotheses and theories play a central role in science; the idea that any observer can study the world except through the spectacles of his or her preconceptions and expectations is not sustainable. As these preconceptions change with progressively changing understanding of the world, the nature of science itself changes, and what was once considered conventionally scientific no longer seems so in retrospect.  


The scientific method is an ongoing cycle, constantly developing more useful, accurate and comprehensive models and methods. For example, when Einstein developed the Special and General Theories of Relativity, he did not discount Newton's ''Principia''. On the contrary, if one reduces out the astronomically large, the vanishingly small, and the extremely fast from Einstein's theories — all phenomena that Newton could not have observed — one is left with Newton's equations. Einstein's theories are expansions and refinements of Newton's theories, and the observations that increase our confidence in them also increase our confidence in Newton's approximations to them.
A [[hypothesis]] is a proposed explanation of a phenomenon. It is an “inspired guess”, a “bold speculation” , embedded in current understanding yet going beyond that to assert something that we do not know for sure as a way of explaining something not otherwise accounted for. Scientists use many different means to generate hypotheses including their own creative imagination, ideas from other fields, [[induction (philosophy)|induction]], [[Bayesian inference]]. [[Charles Sanders Peirce]] described the incipient stages of [[inquiry]], instigated by the "irritation of doubt" to venture a plausible guess, as ''[[Inquiry#Abduction|abductive reasoning]]''. The history of science is filled with stories of scientists claiming a "flash of inspiration", or a hunch, which then motivated them to look for evidence to support or refute their idea.  [[Michael Polanyi]] made such creativity the centrepiece of his discussion of methodology.  


The Keystones of Science project, sponsored by the journal ''[[Science (journal)|Science]]'', has selected a number of scientific articles from that journal and annotated them, illustrating how different parts of each article embody the scientific method.  [http://www.sciencemag.org/feature/data/scope/keystone1/ Here] is an annotated example of the scientific method example.
The philosopher  [[Karl Popper]] , in a book that Sir Peter Medawar called one of the most important documents of the 20th century, argued forcefully that argued that


A linearized, pragmatical scheme of the four above points is sometimes offered as a guideline for proceeding:
<div class="boilerplate metadata" id="attention" style="background-color: #FFFCE6; margin: 0 2.5%; padding: 0 10px; border: 1px solid #aaa;"> 
# Define the question
# Gather information and resources
# Form hypothesis
# Perform experiment and collect data
# Analyze data
# Interpret data and draw conclusions that serve as a starting point for new hypotheses
# Publish results
</div>


While this schema outlines a typical hypothesis/testing method, some philosophers, historians and sociologists of science (perhaps most notably [[Paul Feyerabend]]) claim that such descriptions of scientific method have little relation to the ways science is actually practiced.
He argued that the essential quality of a good hypothesis is that it must be [[falsifiable]]; it must be challengeable by experiments, and he argued that science is this process of challenging hypotheses by experiments, and that progress is made when a hypothesis resists determined attempts at disproof, and becomes provisionally accepted as a valuable tool for adding to our understanding. Conversely, he argued that a proposition or theory cannot be called scientific if it does not admit the possibility of being shown false. It must, at least in principle, be possible to make an observation that would show the proposition to be false, otherwise the proposition is vacuous, with, as Popper put it, no connection with the real world. For Popper therefore, explanations without any predictive content, and he argued that the explanations of Freudian [[psychoanalysis]], those of [[Marxism]], and those of [[astrology]], were all examples of ‘empty’ unscientific theories.


====[[Image:DNA icon (25x25).png]]DNA example====
For Popper, a theory was the context within which hypotheses are developed, and which determined which things were important to investigate and which were not. The theory encompasses the preconceptions by which the world is viewed, and defines the ways we study it and understand it. A theory thus has a profound importance, without a theory no science is possible. He thus recognised that you do not discard a theory lightly, and that a theory might be inconsistent with many known facts (anomalies). However, the recognition of anomalies drives scientists to elaborate or adjust the theory, and if the anomalies continue to accumulate, will drive them to develop alternative theories. He also explained that theories always contain many elements that are not falsifiable, but he argued that these should be kept to a minimum, and that the content of a theory should be judged by the extent to which it inspired testable hypotheses (although this is certainly not his only criterion). Scientists also seek theories that are "[[elegant]]" or "[[beautiful]]"; these terms are subjective and hard to define, but they express the scientists expectation that a theory should yield clear, simple explanations of complex phenomena, that are intellectually satisfying in the sense of appearing to be logically coherent, rich in content, and involving no miracles or other supernatural devices.
: Each element of scientific method is illustrated below by an example from the discovery of the structure of [[DNA]]:
:*''[[#DNA/characterizations|DNA/characterizations]]''
:*''[[#DNA/hypotheses|DNA/hypotheses]]''
:*''[[#DNA/predictions|DNA/predictions]]''
:*''[[#DNA/experiments|DNA/experiments]]''




===Characterizations===
Popper thus argued that progress in science depends upon attempted falsification of hypotheses, and that most progress came by success in falsifying them; disproof is logically sound, support by induction is logically unsound. "Verifiability" in Popper's view was not the object or intent of science, just a weak by-product of a failed attempt at falsification.
The scientific method depends upon increasingly more sophisticated characterizations of subjects of the investigation. (The ''subjects'' can also be called ''[[list of unsolved problems|lists of unsolved problems]]'' or the ''unknowns''.) For example, [[Benjamin Franklin]] correctly characterized [[St. Elmo's fire]] as [[electrical]] in [[nature]], but it has taken many experiments and theory to establish this.  


Scientific measurements taken are usually tabulated, graphed, or mapped, and statistical analyses of them. The measurements might be made in a controlled setting, such as a laboratory, or made on more or less inaccessible or unmanipulatable objects such as stars or human populations. The measurements often require specialized instruments such as thermometers, microscopes, or voltmeters, and the progress of a scientific field is usually intimately tied to their development.
The historian of science [[Thomas Kuhn]] maintains that the "route from theory to measurement can almost never be travelled backward"; which theory is tested is dictated by the nature of the theory itself. This led Kuhn to argue that "once it has been adopted by a profession ... no theory is recognized to be testable by any quantitative tests that it has not already passed".<ref>
[[Thomas Kuhn|Kuhn TS]] (1961) The Function of Measurement in Modern Physical Science ''ISIS'' 52:161–193
* Kuhn TS (1962)''The Structure of Scientific Revolutions'', University of Chicago Press, Chicago, IL, 1962.  2nd edition 1970. 3rd edition 1996.
* Kuhn TS (1977) ''The Essential Tension, Selected Studies in Scientific Tradition and Change'', University of Chicago Press, Chicago, IL</ref>


Measurements also demand the use of ''[[operational definition]]s''. A scientific quantity is defined by how it is measured, as opposed to some more vague definition. For example, [[electrical current]], measured in amperes, can be operationally defined in terms of the mass of silver deposited in a certain time on an electrode in an electrochemical device that is described in some detail. The operational definition of a thing often relies on comparisons with standards: the operational definition of "mass" ultimately relies on the use of an artifact, such as a certain kilogram of platinum-iridium kept in a laboratory in France.


The scientific definition of a term sometimes differs substantially from their [[natural language]] usage. For example, [[mass]] and [[weight]] overlap in meaning in common discourse, but have distinct meanings in physics. Scientific quantities are often characterized by their [[units of measure]] which can later be described in terms of conventional [[physical unit]]s when communicating the work.  
==Experiments and observations==
[[Werner Heisenberg]] in a quote that he attributed to [[Albert Einstein]] , stated [Heisenberg 1971]:
: The phenomenon under observation produces certain events in our measuring apparatus. As a result, further processes take place in the apparatus, which eventually and by complicated paths produce sense impressions and help us to fix the effects in our consciousness.  Along this whole path—from the phenomenon to its fixation in our consciousness—we must be able to tell how nature functions, must know the natural laws at least in practical terms, before we can claim to have observed anything at all. Only theory, that is, knowledge of natural laws, enables us to deduce the underlying phenomena from our sense impressions.
For a large part of the 20th century, the dominant approach to science has been [[reductionism]] – the attempt to explain all phenomena in terms of basic laws of physics and chemistry. In many fields, such explanations are very remote,  and all explanations involve “high level” concepts, but the reductionist belief has been that these high level concepts are all ultimately reducible to physics and chemistry, and that the role of science is to progressively explain high level concepts by concepts closer and closer to the basic physics and chemistry. For example, to explain the behaviour of individuals we might refer to motivational states such as hunger or stress or anxiety. We believe that these reflect features of the activity of the brain that are still poorly understood, but can investigate the brain areas that house these motivational drives, calling them, for example, “hunger centres”, These centres each involve many neural networks – interconnected nerve cells, and the functions of each network we can again probe in more detail. These networks in turn are composed of specialised neurones, whose behaviour can be analysed individually. These specialised nerve cells have distinctive properties that are the product of a genetic program that is activated in development – and so reducible to molecular biology. However, while behaviour is in this sense reducible to basic elements, explanations in terms of these basic elements have at present little predictive value in general, because the uncertainties in our understanding are too great, so explanations of behaviour still largely depend upon the high level constructs.
Historically, the converse philosophical position to reductionism has taken many names, but the clearest debate was between “vitalism” and reductionism. Vitalism held essentially that some features of living organisms, including life itself, were not amenable to a physico-chemical explanation, and so asserted that high level constructs were essential to understanding and explanation.
Scientific measurements are usually tabulated, graphed, or mapped, and statistical analyses of them; often these representations of the data using tools and conventions that are at a given time, accepted and understood by scientists working within a given field. The measurements often require specialized instruments such as thermometers, microscopes, or voltmeters, whose properties and limitations are familiar to others in the field, and the progress of a scientific field is usually intimately tied to their development. Measurements also demand the use of ''[[operational definition]]s''. A scientific quantity is defined precisely by how it is measured, in terms that enable other scientists to reproduce the measurements. In many cases, this ultimately involves internationally agreed ‘standards’. For example, [[electrical current]], measured in amperes, can be defined in terms of the mass of silver deposited in a certain time on an electrode in an electrochemical device that is described in some detail. The scientific definition of a term sometimes differs substantially from their [[natural language]] usage. For example, [[mass]] and [[weight]] overlap in meaning in common use, but have different meanings in physics. Scientific quantities are often characterized by their [[units of measure]] which can later be described in terms of conventional [[physical unit]]s when communicating the work. Measurements are not reports of absolute truth, all measurements are accompanied by the possibility of error in measurement, so they are usually accompanied by estimates of their [[uncertainty]], This is often estimated by making repeated measurements, and seeing by how much these differ. Counts of things, such as the number of people in a nation at a particular time, may also have an uncertainty due to limitations of the method used. Counts may only represent a sample of desired quantities, with an uncertainty that depends upon the sampling method used and the number of samples taken.
==The scientific method in practice==
The UK Research Charity [[Cancer UK]] gave an outline of the scientific method, as practised by their scientists [http://info.cancerresearchuk.org/cancerandresearch/aboutcancerresearch/thescientificmethod/]. The quotes that follow are all from this outline
<blockquote> ‘’[Scientists] start by making an educated guess about what they think the answer might be, based on all the available evidence they have. This is known as forming an hypothesis. They then try to prove if their hypothesis is right or wrong.
Researchers carry out carefully designed studies, often known as experiments, to test their hypothesis. They collect and record detailed information from the studies. They look carefully at the results to work out if their hypothesis is right or wrong…’’ </blockquote>
Once predictions are made, they can be ''tested'' by experiments. If the outcome contradicts the predictions, then the hypotheses are called into question and explanations may be sought. Sometimes experiments are conducted incorrectly. If the results confirm the predictions, then the hypotheses are considered likely to be correct but might still be wrong and are subject to [[#Evaluations and iterations |further testing.]] Scientists assume an attitude of openness and accountability on the part of those conducting an experiment. Detailed record keeping is essential, to provide evidence of the effectiveness and integrity of the procedure and to also assist in reproducing the experimental results. This tradition can be seen in the work of [[Hipparchus (astronomer)|Hipparchus (190 BCE - 120 BCE)]], when determining a value for the precession of the Earth over 2100 years ago, and 1000 years before Al-Batani.
===Peer review===
<blockquote> ‘’…Once they have completed their study, the researchers write up their results and conclusions. And they try to publish them as a paper in a scientific journal.
Before the work can be published, it must be checked by a number of independent researchers who are experts in a relevant field. This process is called ‘peer review’, and involves scrutinising the research to see if there are any flaws that invalidate the results…’’ </blockquote>
Manuscripts submitted for publication in scientific journals are normally sent by the editor to (usually one to three) fellow (usually anonymous) scientists who are familiar with the field for evaluation. The referees may or may not recommend publication, publication with suggested modifications, or, sometimes, publication in another journal. This helps to keep the scientific literature free of unscientific work, reduces obvious errors, and generally otherwise improve the quality of the scientific literature. The peer review process has been criticised, but has been very widely adopted by the scientific community.  


Measurements are also usually accompanied by estimates of their [[uncertainty]]. The uncertainty is often estimated by making repeated measurements. Uncertainties may also be calculated by consideration of the uncertainties of the individual underlying quantities that are used. Counts of things, such as the number of people in a nation at a particular time, may also have an uncertainty due to limitations of the method used. Counts may only represent a sample of desired quantities, with an uncertainty that depends upon the sampling method used and the number of samples taken.  
Originality, importance and interest are particularly important in “high impact” journals - see for example the [http://www.nature.com/nature/submit/get_published/index.html author guidelines] for ''[[Nature (journal)|Nature]]''.  
Criticisms (see [[Critical theory]]) of these restraints are that they are so nebulous in definition (e.g. "good scientific practice") and open to ideological, or even political, manipulation that they often serve to censor rather than promote scientific discovery. Apparent censorship through refusal to publish ideas unpopular with mainstream scientists (unpopular because of ideological reasons and/or because they seem to contradict long held scientific theories) has soured the popular perception of scientists as being neutral or seekers of truth and often denigrated popular perception of science.


New theories sometimes arise upon realizing that certain terms had not previously been sufficiently clearly defined. For example, [[Albert Einstein|Albert Einstein's]] first paper on [[Special relativity|relativity]] begins by defining [[Relativity of simultaneity|simultaneity]] and the means for determining [[length]]. These ideas were skipped over by [[Isaac Newton]] with, "''I do not define [[time in physics#Galileo's water clock|time]], space, place and [[motion (physics)|motion]], as being well known to all.''" Einstein's paper then demonstrates that they (viz., absolute time and length independent of motion) were approximations. [[Francis Crick]] cautions us that when characterizing a subject, however, it can be premature to define something when it remains ill-understood.<ref>Crick F (1994) ''The Astonishing Hypothesis'' ISBN 0-684-19431-7 p.20</ref> In Crick's study of consciousness, he actually found it easier to study awareness in the [[visual system]], rather than to study Free Will, for example. His cautionary example was the gene;  the gene was much more poorly understood before Watson and Crick's pioneering discovery of the structure of DNA; it would have been counterproductive to spend much time on the definition of the gene, before them.
==The scientific literature==
<blockquote> ‘’…If the study is found to be good enough, the findings are published and acknowledged by the wider scientific community…’’ </blockquote>
However Thomas Kuhn argued that scientists are


====[[Image:DNA icon (25x25).png]]DNA/characterizations====
Sir Peter Medawar, Nobel laureate in Physiology and Medicinein his article [http://maagar.openu.ac.il/opus/static/binaries/editor/bank66/medawar_paper_fraud_1.pdf  “Is the scientific paper a fraud?”] answered yes, “The scientific paper in its orthodox form does embody a totally mistaken conception, even a travesty, of the nature of scientific thought.” In scientific papers, the results of an experiment are interpreted only at the end, in the discussion section, giving the impression that those conclusions are drawn by induction or deduction from the reported evidence. Instead, explains Medawar, the expectations that a scientist begins with provide the incentive for the experiments, and determine their nature, and they determine which observations are relevant and which are not. Only in the light of these initial expectations that the activities described in a paper have any meaning at all. The expectation, the original hypothesis, according to Medawar, is not the product of inductive reasoning but of inspiration, educated guesswork. Medawar was echoing Karl Popper, who proclaimed that
: [[DNA#The history of DNA research|The history of the discovery]] of the structure of [[DNA]] is a classic example of [[#Elements of scientific method|the elements of scientific method]]: in [[1950]] it was known that [[genetic inheritance]] had a mathematical description, starting with the studies of [[Gregor Mendel]], but the mechanism  was unclear. Researchers in [[William Lawrence Bragg|Bragg's]] laboratory at [[University of Cambridge|Cambridge University]] made [[X-ray]] [[diffraction]] pictures of various [[molecule]]s, starting with [[crystal]]s of [[salt]], and proceeding to more complicated substances. Using clues painstakingly assembled over the course of decades, beginning with its chemical composition, it was determined that it should be possible to characterize the physical structure of DNA, and the X-ray images would be the vehicle.


====Precession of Mercury====
==Confirmation==
[[Image:Perihelion_precession.jpg|thumb|right|[[Precession]] of the [[perihelion]] (very exaggerated)]]
<blockquote> ‘’…But, it isn’t enough to prove a hypothesis once. Other researchers must also be able to repeat the study and produce the same results, if the hypothesis is to remain valid…’’ </blockquote>
The characterization element can require extended and extensive study. It took thousands of years of measurements, from the [[Chaldea]]n, [[India]]n, [[Persian Empire|Persia]]n, [[Greece|Greek]], [[Arab]]ic and [[European]] astronomers, to record the motion of planet [[Earth]]. Newton condensed these measurements into consequences of his [[laws of motion]], but the [[perihelion]] of the planet [[Mercury (planet)|Mercury]]'s [[orbit]] exhibits a precession which is not fully explained by Newton's laws of motion. The observed difference for Mercury's precession, between Newtonian theory and relativistic theory (approximately 43 arc-seconds per century), was one of the things that occurred to Einstein as a possible early test of his theory of [[General Relativity]].
Sometimes experimenters make systematic errors during their experiments, Consequently, it is a common practice for other scientists to attempt to repeat experiments, especially experiments that have yielded unexpected results<ref> [[Georg Wilhelm Richmann]] was killed by [[lightning]] ([[1753]]) when attempting to replicate the [[1752]] [[kite flying|kite]] [[experiment]] of [[Benjamin Franklin]]. See, e.g., Physics Today, Vol. 59, #1, p42. [http://www.physicstoday.org/vol-59/iss-1/p42.html]</ref>. Accordingly, scientists keep detailed records of their experiments, to provide evidence of their effectiveness and integrity and assist in reproduction. However, it is not possible for a scientist to record ''everything'' that took place in an experiment. He must select the facts that he believes are relevant to the experiment. This may lead to problems if some supposedly irrelevant feature is questioned. For example, [[Heinrich Hertz]] did not report the size of the room that he used to test Maxwell's equations, and this turned out to account for a deviation in the results. The problem is that parts of the theory must be assumed in order to select and report the experimental conditions. Observations are thus sometimes described as being 'theory-laden'.
It seems to be only very rarely that scientists falsify their results; any scientist who does so takes an enormous risk, because if the claim is important it is likely to be subjected to very detailed scrutiny, and the reputation of a scientist depends upon the credibility of his or her work. Nevertheless there have been many well publicised examples of scientific fraud, and some have blamed the insecurity of employment of scientists and the extreme pressure to win grant funding for these instances. Under Federal regulations as published in the Federal Register, vol 65, no. 235, December 6, 2000 “A finding of research misconduct requires that:
There be a significant departure from accepted practices of the relevant research community; and
The misconduct be committed intentionally, or knowingly, or recklessly; and
The allegation be proven by a preponderance of evidence.”
Honor in Science, published by  Sigma Xi , quotes [[C.P. Snow]] (The Search, 1959):“The only ethical principle which has made science possible is that the truth shall be told all the time. If we do not penalise false statements made in error, we open up the way, don’t you see, for false statements by intention. And of course a false statement of fact, made deliberately, is the most serious crime a scientist can commit.”
It goes on to say:
“It is not sufficient for the scientist to admit that all human activity, including research, is liable to involve errors; he or she has a moral obligation to minimize the possibility of error by checking and rechecking the validity of the data and the conclusions that are drawn from the data.”
==Statistics==
<blockquote>‘’…If the initial study was carried out using a small number of samples or people, larger studies are also needed. This is to make sure the hypothesis remains valid for bigger group and isn't due to chance variation…’’ </blockquote>
There is an important school of Bayesian statistics that seeks to provide a statistical basis for support by induction, and some areas of science use these approaches; but in much of science this approach is not tenable because of the difficulty of attaching a priori probabilities in any meaningful way to the alternative predicted outcomes of an experiment. Popper was a mathematical logician, and argued strongly against Bayesian approaches. Popper was interested in how "support" for a theory could be measures by quantifying the degree of corroborative support, he did not dismiss statistical approaches lightly and explored their utility in detail. But in appendix ix to The Logic he states: As to degree of corroboration, it is nothing but a measure of the degree to which hypothesis h has been tested...it must not be interpreted therefore as a degree of the rationality of our belief in the truth of h...rather it is a measure of the rationality of accepting, tentatively, a problematic guess


===Hypothesis development===
==Progress in science==
A [[hypothesis]] is a suggested explanation of a phenomenon, or a reasoned proposal suggesting a possible correlation between or among a set of phenomena. Hypotheses may have the form of a [[mathematical model]], or they can be formulated as [[existential quantification|existential statements]], stating that some particular instance of the phenomenon being studied has some characteristic and causal explanations, which have the general form of [[Universal quantification|universal statements]], stating that every instance of the phenomenon has a particular characteristic.  
<blockquote> ‘’…Over time, scientific opinion can change. This is because new technologies can allow us to re-examine old questions in greater detail.’’ </blockquote>
 
Scientists are free to use whatever resources they have — their own creativity, ideas from other fields, [[induction (philosophy)|induction]], [[Bayesian inference]], and so on — to imagine possible explanations for a phenomenon under study. [[Charles Sanders Peirce]] described the incipient stages of [[inquiry]], instigated by the "irritation of doubt" to venture a plausible guess, as ''[[Inquiry#Abduction|abductive reasoning]]''.  The history of science is filled with stories of scientists claiming a "flash of inspiration", or a hunch, which then motivated them to look for evidence to support or refute their idea.  [[Michael Polanyi]] made such creativity the centrepiece of his discussion of methodology.
 
[[Karl Popper]] argued that a hypothesis must be [[falsifiable]], and that a proposition or theory cannot be called scientific if it does not admit the possibility of being shown false. It must at least in principle be possible to make an observation that would show the proposition to be false, even if that observation had not yet been made.
 
[[William Glen]] observes that
<blockquote>
the success of a hypothesis, or its service to science, lies not simply in its perceived "truth", or power to displace, subsume or reduce a predecessor idea, but perhaps more in its ability to stimulate the research that will illuminate … bald suppositions and areas of vagueness.<ref>Glen,William (ed.), The Mass-Extinction Debates: How Science Works in a Crisis, Stanford University Press, Stanford, CA, 1994. ISBN 0-8047-2285-4. pp. 37-38.</ref>
</blockquote>
 
In general, scientists tend to look for theories that are "[[elegant]]" or "[[beautiful]]". In contrast to the usual English use of these terms, they here refer to a theory in accordance with the known facts, which is nevertheless relatively simple and easy to handle. If a model is mathematically too complicated, it is hard to deduce any [[#Prediction from the hypothesis|prediction]].  Note that 'simplicity' may be perceived differently by different individuals and cultures.
 
====[[Image:DNA icon (25x25).png]]''DNA/hypotheses''====
: [[Linus Pauling]] proposed that DNA was a triple helix. [[Francis Crick]] and [[James Watson]] learned of Pauling's hypothesis, understood from existing data that Pauling was wrong and realized that Pauling would soon realize his mistake.  So the race was on to figure out the correct structure.  Except that Pauling did not realize at the time that he was in a race!
 
===Predictions from the hypotheses===
Any useful hypothesis will enable [[prediction]]s, by [[reasoning]] including [[deductive reasoning]]. It might predict the outcome of an experiment in a laboratory setting or the observation of a phenomenon in nature. The prediction can also be statistical and only talk about probabilities.
 
====[[Image:DNA icon (25x25).png]]''DNA/predictions''====
 
: When [[James D. Watson|Watson]] and Crick hypothesized that DNA was a double helix, [[Francis Crick]] predicted that an X-ray diffraction image of DNA would show an X-shape. Also in their first paper they predicted that the [[double helix]] structure that they discovered would prove important in biology writing "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material".


====''General Relativity''====
====''General Relativity''====
Line 106: Line 82:
Einstein's theory of [[General Relativity]] makes several specific predictions about the observable structure of [[space-time]], such as a prediction that [[light]] bends in a [[gravitational field]] and that the amount of bending depends in a precise way on the strength of that gravitational field. [[Arthur Eddington]]'s observations made during a [[1919]] [[solar eclipse]] supported General Relativity rather than Newtonian [[gravitation]].
Einstein's theory of [[General Relativity]] makes several specific predictions about the observable structure of [[space-time]], such as a prediction that [[light]] bends in a [[gravitational field]] and that the amount of bending depends in a precise way on the strength of that gravitational field. [[Arthur Eddington]]'s observations made during a [[1919]] [[solar eclipse]] supported General Relativity rather than Newtonian [[gravitation]].


===Experiments===
{{mainarticle|Experiments}}
Once predictions are made, they can be ''tested'' by experiments. If the outcome contradicts the predictions, then the hypotheses are called into question and explanations may be sought. Sometimes experiments are conducted incorrectly. If the results confirm the predictions, then the hypotheses are considered likely to be correct but might still be wrong and are subject to [[#Evaluations and iterations |further testing.]] Scientists assume an attitude of openness and accountability on the part of those conducting an experiment. Detailed record keeping is essential, to provide evidence of the effectiveness and integrity of the procedure and to also assist in reproducing the experimental results. This tradition can be seen in the work of [[Hipparchus (astronomer)|Hipparchus (190 BCE - 120 BCE)]], when determining a value for the precession of the Earth over 2100 years ago, and 1000 years before Al-Batani.
====[[Image:DNA icon (25x25).png]]''DNA/experiments''====
: Before proposing their model Watson and Crick had previously seen x-ray diffraction images by [[Rosalind Franklin]], [[Maurice Wilkins]], and [[Raymond Gosling]].  However, they later reported that Franklin initially rebuffed their suggestion that DNA might be a double helix. Franklin had immediately spotted flaws in the initial hypotheses about the structure of DNA by Watson and Crick. The [http://www.pbs.org/wgbh/nova/photo51/ X-shape] in X-ray images helped confirm the helical structure of DNA.


==Evaluation and iteration==
==See Also==
The scientific process is iterative. At any stage it is possible that some consideration will lead the scientist to repeat an earlier part of the process. Failure to develop an interesting hypothesis may lead a scientist to redefine the subject they are considering. Failure of a hypothesis to produce interesting and testable predictions may lead to reconsideration of the hypothesis or of the definition of the subject. Failure of the experiment to produce interesting results may lead the scientist to reconsidering the experimental method, the hypothesis or the definition of the subject.
[[Models of scientific inquiry]]
[[Pseudoscience]]


Other scientists may start their own research and enter the process at any stage. They might adopt the characterization and formulate their own hypothesis, or they might adopt the hypothesis and deduce their own predictions. Often the experiment is not done by the person who made the prediction and the characterization is based on experiments done by someone else. Published results of experiments can also serve as a hypothesis predicting their own reproducibility.
====[[Image:DNA icon (25x25).png]]''DNA/iterations''====
: After considerable fruitless experimentation, being discouraged by their superior from continuing, and numerous false starts, Watson and Crick were able to infer the essential structure of [[DNA]] by concrete [[model (abstract)|modelling]] [[DNA#Discovery of the structure of DNA|of the physical shapes]] of the [[nucleotide]]s which comprise it. They were guided by the bond lengths which had been deduced by [[Linus Pauling]] and the X-ray diffraction images of [[Rosalind Franklin]].
===Confirmation===
Science is a social enterprise, and scientific work tends to be accepted by the community when it has been confirmed. Crucially, experimental and theoretical results must be reproduced by others within the science community. Researchers have given their lives for this vision; [[Georg Wilhelm Richmann]] was killed by [[lightning]] ([[1753]]) when attempting to replicate the [[1752]] [[kite flying|kite]] [[experiment]] of [[Benjamin Franklin]].<ref>See, e.g., Physics Today, Vol. 59, #1, p42. [http://www.physicstoday.org/vol-59/iss-1/p42.html]</ref>
==Models of scientific inquiry==
{{main|Models of scientific inquiry}}
The classical model of scientific inquiry derives from [[Aristotle]], who distinguished the forms of approximate and exact reasoning, set out the threefold scheme of [[abductive reasoning|abductive]], [[deductive reasoning|deductive]], and [[inductive reasoning|inductive]] inference, and also treated the compound forms such as reasoning by [[analogy]].
{{main|Pragmatic theory of truth}}
[[Charles Peirce]] considered scientific inquiry to be a species of the genus ''inquiry'', which he defined as any means of fixing belief, that is, any means of arriving at a settled opinion on a matter in question.  He observed that inquiry in general begins with a state of uncertainty and moves toward a state of certainty, sufficient at least to terminate the inquiry for the time being.  He graded the prevalent forms of inquiry according to their evident success in achieving their common objective, scoring scientific inquiry at the high end of this scale.  At the low end he placed what he called the ''method of tenacity'', a die-hard attempt to deny uncertainty and fixate on a favored belief.  Next in line he placed the ''method of authority'', a determined attempt to conform to a chosen source of ready-made beliefs.  After that he placed what might be called the ''method of congruity'', also called the ''a priori'', the ''dilettante'', or the ''what is agreeable to reason'' method.  Peirce observed the fact of human nature that almost everybody uses almost all of these methods at one time or another, and that even scientists, being human, use the method of authority far more than they like to admit.  But what recommends the specifically scientific method of inquiry above all others is the fact that it is deliberately designed to arrive at the ultimately most secure beliefs, upon which the most successful actions can be based.
===Computational approaches===
Many subspecialties of [[applied logic]] and [[computer science]], including [[artificial intelligence]], [[computational learning theory]], [[inferential statistics]], and [[knowledge representation]], are concerned with setting out computational, logical, and statistical frameworks for the various types of inference involved in scientific inquiry, in particular, [[abductive reasoning|hypothesis formation]], [[deductive reasoning|logical deduction]], and [[inductive reasoning|empirical testing]].  Some of these draw on [[measure (mathematics)|measures]] of [[complexity]] from [[algorithmic information theory]] to guide the making of predictions from prior [[probability distribution|distributions]] of experience, for example, see the complexity measure called the ''[[speed prior]]'' from which a computable strategy for optimal inductive reasoning can be derived.
==Philosophical issues==
{{main|Philosophy of science}}
Scientific researchers generally express a high level of confidence in scientific method.  What justifies their level of confidence that scientific method, under some conception, model, or recipe, is truly a good way to achieve the knowledge that it promises?  That is a question about the ''grounds of validity'' of scientific method, also referred to as the problem of ''justification'' or ''warrant''. While the philosophy of science has limited direct impact on day-to-day scientific practice, it plays a vital role in justifying and defending the scientific approach. There is disagreement over whether there is a single 'scientific method' or many of them.
Philosophers of science are interested in to what extent the actual practice of scientists conforms to the ''[[method|espoused methods]]'' or the ''[[norm|ostensible norms]]'', to which most of them apparently assent; some question whether scientific knowledge is actually produced by a defined, describable, or determinate [[methodology]] (see, for instance, the writings of [[Paul Feyerabend|Feyerabend]] and [[Thomas Samuel Kuhn|Kuhn]]).
We find ourselves in a world that is not directly understandable. We sometimes disagree about the [[fact]]s of the things we see in the world around us, and some things in the world are at odds with our understanding. The scientific method attempts to provide a way in which we can reach agreement and understanding. A "perfect" scientific method might work in such a way that [[rationality|rational]] application of the method would always result in agreement and understanding; a perfect method would arguably be [[algorithm|algorithmic]], and not leave any room for rational agents to disagree. As with all [[Philosophy|philosophical]] topics, the search has been neither straightforward nor simple. [[Logical positivism|Logical Positivist]], [[empiricism|empiricist]], [[falsifiability|falsificationist]], and other theories have claimed to give a definitive account of the logic of science, but each has been criticised.
[[Werner Heisenberg]] in a quote that he attributed to [[Albert Einstein]] many years later, stated [Heisenberg 1971]:
: It is quite wrong to try founding a theory on observable magnitudes alone. In reality the very opposite happens. It is the theory which decides what we can observe. You must appreciate that observation is a very complicated process. The phenomenon under observation produces certain events in our measuring apparatus. As a result, further processes take place in the apparatus, which eventually and by complicated paths produce sense impressions and help us to fix the effects in our consciousness.  Along this whole path—from the phenomenon to its fixation in our consciousness—we must be able to tell how nature functions, must know the natural laws at least in practical terms, before we can claim to have observed anything at all. Only theory, that is, knowledge of natural laws, enables us to deduce the underlying phenomena from our sense impressions. When we claim that we can observe something new, we ought really to be saying that, although we are about to formulate new natural laws that do not agree with the old ones, we nevertheless assume that the existing laws—covering the whole path from the phenomenon to our consciousness—function in such a way that we can rely upon them and hence speak of “observation”.
Considerations such as these led [[Feyerabend]] to deny that science is genuinely a methodological process. In his book ''[[Against Method]]'' he argues that scientific progress is ''not'' the result of applying any particular method. In essence, he says that "anything goes", by which he meant that for any specific methodology or norm of science, successful science has been done in violation of it. Criticisms such as his led to a rise in the study of the scientific enterprise as a social phenomenon. To the degree that sociological studies focus on cooperation and appreciation as well as conflict both within the scientific communities and beyond, however, the [[Science studies|sociology of science]] is also quite capable of accounting for sociological components of the ''success'' of the [[scientific enterprise]] which for much of the 20th century had fairly widely been taken as granted.  The [[strong programme]] has put forward a perspective of just this kind.
===Problem of demarcation===
The problem of evaluating a system of thought with regard to its status as science is often called the [[demarcation problem]].  The criteria for a system of assumptions, methods, and theories to qualify as science vary in their details from application to application, but they typically include (1) the formulation of hypotheses that meet the logical criterion of [[contingency]], defeasibility, or [[falsifiability]] and the closely related [[empirical]] and [[practical]] criterion of [[testability]], (2) a grounding in empirical evidence, and (3) the use of scientific method. The procedures of science typically include a number of [[heuristic]] guidelines, such as the principles of conceptual economy or theoretical [[parsimony]] that fall under the rubric of [[Ockham's razor]]. The following is a list of additional features that are highly desirable in a scientific theory.
:* Consistent.  Generates no obvious logical contradictions, and [[scientific formalism|'saves the phenomena']], being consistent with observation.
:* Parsimonious.  Economical in the number of assumptions and hypothetical entities.
:* Pertinent.  Describes and explains observed phenomena.
:* [[Falsifiability|Falsifiable]] and [[Testability|testable]]. 
:* Reproducible.
:* Correctable and dynamic. 
:* Integrative, robust, and corrigible.  Subsumes previous theories as approximations, and allows possible subsumption by future theories.  See [[Correspondence principle]]
:* Provisional or tentative.  Does not assert the absolute certainty of the theory.
==Communication, community, culture==
Often the scientific method is not employed by a single person, but by several cooperating directly or indirectly. Such cooperation can be regarded as one of the defining elements of a [[scientific community]]. Various techniques have been developed to ensure the integrity of the scientific method within such an environment.
===Peer review evaluation===
Scientific journals use a process of ''[[peer review]]'', in which manuscripts are submitted by editors of scientific journals to (usually one to three) fellow (usually anonymous) scientists familiar with the field for evaluation. The referees may or may not recommend publication, publication with suggested modifications, or, sometimes, publication in another journal. This helps to keep the scientific literature free of unscientific work, reduces obvious errors, and generally otherwise improve the quality of the scientific literature. The peer review process has been criticised, but has been very widely adopted by the scientific community.
===Documentation and replication===
Sometimes experimenters may make systematic errors during their experiments, or (in rare cases) deliberately falsify their results. Consequently, it is a common practice for other scientists to attempt to repeat the experiments in order to duplicate the results, thus further validating the hypothesis. As a result, experimenters are expected to maintain detailed records of their experiments, to provide evidence of the effectiveness and integrity of the procedure and assist in reproduction. These procedural records may also assist in the conception of new experiments to test the hypothesis, and may prove useful to engineers who might examine the potential practical applications of a discovery. Note that it is not possible for a scientist to record ''everything'' that took place in an experiment. He must select the facts he believes to be relevant to the experiment and report them. This may lead  to problems if some supposedly irrelevant feature is questioned. For example, [[Heinrich Hertz]] did not report the size of the room used to test Maxwell's equations, which later turned out to account for a small deviation in the results. The problem is that parts of the theory itself need to be assumed in order to select and report the experimental conditions. Observations are sometimes hence described as being 'theory-laden'.
===Dimensions of practice===
The primary constraints on contemporary western science are:
* Publication, i.e. [[Peer review]]
* Resources (mostly funding)
Both of these constraints indirectly bring in a scientific method &mdash; work that too obviously violates the constraints will be difficult to publish and difficult to get funded. Journals do not require submitted papers to conform to anything more specific than "good scientific practice" and this is mostly enforced by peer review. Originality, importance and interest are more important - see for example the [http://www.nature.com/nature/submit/get_published/index.html author guidelines] for ''[[Nature (journal)|Nature]]''.
Criticisms (see [[Critical theory]]) of these restraints are that they are so nebulous in definition (e.g. "good scientific practice") and open to ideological, or even political, manipulation apart from a rigorous practice of a scientific method, that they often serve to censor rather than promote scientific discovery. Apparent censorship through refusal to publish ideas unpopular with mainstream scientists (unpopular because of ideological reasons and/or because they seem to contradict long held scientific theories) has soured the popular perception of scientists as being neutral or seekers of truth and often denigrated popular perception of science as a whole.
==History==
{{main|History of scientific method}}
:''See also [[Timeline of the history of scientific method]]''
The development of the scientific method is inseparable from the history of science itself. [[Ancient Egypt]]ian documents, such as early [[papyri]], describe methods of medical diagnosis. In [[Ancient Greece|ancient Greek]] culture, the first elements of the inductive scientific method clearly become well established. Significant progress in methodology was made in [[early Muslim philosophy]], in particular using experiments to distinguish between competing scientific theories set within a generally empirical orientation. The fundamental tenets of the basic scientific method crystallized no later than the rise of the modern [[physical science]]s, in the [[17th century|17th]] and [[18th century|18th]] centuries. In his work ''[[Novum Organum]]'' ([[1620]]) — a reference to [[Aristotle]]'s ''[[Organon]]'' — [[Francis Bacon]] outlined a new system of [[logic]] to improve upon the old [[philosophy|philosophical]] process of [[syllogism]]. Then, in [[1637]], [[René Descartes]] established the framework for a scientific method's guiding principles in his treatise, ''[[Discourse on Method]]''. These writings are considered critical in the historical development of the scientific method.
In the late 19th century, [[Charles Sanders Peirce]] proposed a schema that would turn out to have considerable influence in the development of current scientific method generally.  Speaking in broader context in "How to Make Our Ideas Clear" (1878) [http://members.door.net/arisbe/menu/library/bycsp/ideas/id-frame.htm], Peirce outlined an objectively verifiable method to test the truth of putative knowledge on a way that goes beyond mere foundational alternatives, focusing upon both ''deduction'' and ''induction''.  He thus placed induction and deduction in a complementary rather than competitive context (the latter of which had been the primary trend at least since [[David Hume]], who wrote in the mid-to-late 18th century). Secondly, Peirce put forth the basic schema for hypotheis/testing that continues to prevail today. Extracting the theory of inquiry from its raw materials in classical logic, he refined it in parallel with the early development of symbolic logic to address the then-current problems in scientific reasoning. Peirce examined and articulated the three fundamental modes of reasoning that, as discussed above, play a role in inquiry today, the processes currently known as [[abductive reasoning|abductive]], [[deductive reasoning|deductive]], and [[inductive reasoning|inductive]] inference.
[[Karl Popper]] (1902-1994), beginning in the 1930s argued that a hypothesis must be [[falsifiable]] and, following Peirce and others, that science would best progress using deductive reasoning as its primary emphasis, known as [[critical rationalism]].  His astute formulations of logical procedure helped to rein in exessive use of inductive speculation upon inductive speculation, and also strengthened the conceptual foundation for today's peer review procedures.


==Notes and references==
==Notes and references==
<references/>
<references/>


* [[Aristotle]], "[[Prior Analytics]]", [[Hugh Tredennick]] (trans.), pp. 181-531 in ''Aristotle, Volume&nbsp;1'', [[Loeb Classical Library]], William Heinemann, London, UK, 1938.
* [[Charles Sanders Peirce|Peirce CS]], ''Essays in the Philosophy of Science'', Vincent Tomas (ed.), Bobbs–Merrill, New York, NY, 1957.
* [[Charles Sanders Peirce|Peirce CS]], "Lectures on Pragmatism", Cambridge, MA, March 26 – May 17, 1903.  Reprinted in part, ''Collected Papers'', CP 5.14–212.  Reprinted with Introduction and Commentary, Patricia Ann Turisi (ed.), ''Pragmatism as a Principle and a Method of Right Thinking:  The 1903 Harvard "Lectures on Pragmatism"'', State University of New York Press, Albany, NY, 1997.  Reprinted, pp. 133–241, Peirce Edition Project (eds.), ''The Essential Peirce, Selected Philosophical Writings, Volume 2 (1893–1913)'', Indiana University Press, Bloomington, IN, 1998.
* [[Charles Peirce|Peirce, C.S.]], ''Collected Papers of Charles Sanders Peirce'', vols. 1-6, [[Charles Hartshorne]] and [[Paul Weiss (philosopher)|Paul Weiss]] (eds.), vols. 7-8, [[Arthur W. Burks]] (ed.), Harvard University Press, Cambridge, MA, 1931-1935, 1958.  Cited as CP vol.para.


==Further reading==
==Further reading==
*The Keystones of Science project, sponsored by the journal ''[[Science (journal)|Science]]'', has selected a number of scientific articles from that journal and annotated them, illustrating how different parts of each article embody the scientific method.  [http://www.sciencemag.org/feature/data/scope/keystone1/ Here] is an annotated example of the scientific method example.
* [[Francis Bacon (philosopher)|Bacon, Francis]] ''Novum Organum (The New Organon)'', 1620.  Bacon's work described many of the accepted principles, underscoring the importance of [[Theory]], empirical results, data gathering, experiment, and independent corroboration.
* [[Francis Bacon (philosopher)|Bacon, Francis]] ''Novum Organum (The New Organon)'', 1620.  Bacon's work described many of the accepted principles, underscoring the importance of [[Theory]], empirical results, data gathering, experiment, and independent corroboration.
* [[Henry H. Bauer|Bauer HH]], ''Scientific Literacy and the Myth of the Scientific Method'', University of Illinois Press, Champaign, IL, 1992
* [[Henry H. Bauer|Bauer HH]], ''Scientific Literacy and the Myth of the Scientific Method'', University of Illinois Press, Champaign, IL, 1992
Line 201: Line 99:
* [[Richard J. Bernstein|Bernstein RJ]] (1983) ''Beyond Objectivism and Relativism:  Science, Hermeneutics, and Praxis'', University of Pennsylvania Press, Philadelphia, PA
* [[Richard J. Bernstein|Bernstein RJ]] (1983) ''Beyond Objectivism and Relativism:  Science, Hermeneutics, and Praxis'', University of Pennsylvania Press, Philadelphia, PA
* [[John Dewey|Dewey, John]] (1991) ''How We Think'', D.C. Heath, Lexington, MA, 1910.  Reprinted, [[Prometheus Books]], Buffalo, NY
* [[John Dewey|Dewey, John]] (1991) ''How We Think'', D.C. Heath, Lexington, MA, 1910.  Reprinted, [[Prometheus Books]], Buffalo, NY
* [[Paul Feyerabend|Feyerabend PK]] (1975) ''Against Method, Outline of an Anarchistic Theory of Knowledge'', 1st published, 1975.  Reprinted, Verso, London, UK, 1978.
* [[Werner Heisenberg|Heisenberg, Werner]] (1971) ''Physics and Beyond, Encounters and Conversations'', A.J. Pomerans (trans.), Harper and Row, New York, NY  pp.63–64
* [[Werner Heisenberg|Heisenberg, Werner]] (1971) ''Physics and Beyond, Encounters and Conversations'', A.J. Pomerans (trans.), Harper and Row, New York, NY  pp.63–64
* [[Thomas Kuhn|Kuhn TS]] (1961) The Function of Measurement in Modern Physical Science ''ISIS'' 52:161–193
* Kuhn TS (1962)''The Structure of Scientific Revolutions'', University of Chicago Press, Chicago, IL, 1962.  2nd edition 1970.  3rd edition 1996.
* Kuhn TS (1977) ''The Essential Tension, Selected Studies in Scientific Tradition and Change'', University of Chicago Press, Chicago, IL
* [[Bruno Latour|Latour, Bruno]], ''Science in Action, How to Follow Scientists and Engineers through Society'', Harvard University Press, Cambridge, MA, 1987.
* [[Bruno Latour|Latour, Bruno]], ''Science in Action, How to Follow Scientists and Engineers through Society'', Harvard University Press, Cambridge, MA, 1987.
* [[William McComas|McComas WF]], ed. [http://www.usc.edu/dept/education/science-edu/Myths%20of%20Science.pdf The Principle Elements of the Nature of Science: Dispelling the Myths], from ''The Nature of Science in Science Education'', pp53-70, Kluwer Academic Publishers, Netherlands 1998.
* [[William McComas|McComas WF]], ed. [http://www.usc.edu/dept/education/science-edu/Myths%20of%20Science.pdf The Principle Elements of the Nature of Science: Dispelling the Myths], from ''The Nature of Science in Science Education'', pp53-70, Kluwer Academic Publishers, Netherlands 1998.
* [[Henri Poincaré|Poincaré H]] (1905) ''Science and Hypothesis'' [http://spartan.ac.brocku.ca/~lward/Poincare/Poincare_1905_toc.html Eprint]
* [[Henri Poincaré|Poincaré H]] (1905) ''Science and Hypothesis'' [http://spartan.ac.brocku.ca/~lward/Poincare/Poincare_1905_toc.html Eprint]
* [[Karl Popper|Popper KR]] (1982) ''Unended Quest, An Intellectual Autobiography'', Open Court, La Salle, IL
.
* [[Paul Thagard|Thagard, Paul]], ''Conceptual Revolutions'', Princeton University Press, Princeton, NJ, 1992.


==External links==
==External links==

Revision as of 07:33, 26 December 2006

The scientific method is how scientists investigate phenomena and acquire new knowledge. It is based on observable, empirical, measurable evidence. Scientists propose hypotheses to explain phenomena, and formulat. theories that encompass whole domains of inquiry and bind hypotheses together into logically coherent wholes. They design experimental studies to elaborate theories and test hypotheses.

"Science is a way of thinking much more than it is a body of knowledge." (Carl Sagan[1]).

Elements of scientific method

According to Charles Darwin ,

". . .science consists in grouping facts so that general laws or conclusions may be drawn from them."

This simple account begs many fundamental questions. What do we mean by ‘facts’? How much can we trust our senses to enable us to believe that what we see is true? How exactly do scientists ‘group’ facts? How do they select which facts to pay attention to, and is it even possible to do this in an objective way? And having done this, how exactly do they go about drawing any broader conclusions from the facts that they assemble? How can we know ‘’more’’ than we observe directly?

We live in a world that is not directly understandable. We sometimes disagree about the ‘facts’ we see around us, and some things in the world are at odds with our understanding. What we call the “scientific method” is an account of how scientists attempt to reach agreement and understanding, to provide explanations that will be consistent with the world and will withstand critical logical and experimental scrutiny. A "perfect" scientific method might work in such a way that its rational application would always result in agreement and understanding; a perfect method would arguably be algorithmic, and not leave any room for rational agents to disagree. Logical Positivist, empiricist, falsificationist, and other theories have claimed to give a definitive account of the logic of science, but each has been criticised.

The success of science, as measured by the technological achievements that have progressively changed our world, have led many to the conclusion that this must reflect the success of rules that scientists follow in their research. However, not all philosophers accept this conclusion; notably, the philosopher Paul Feyerabend denied that science is genuinely a methodological process. In his book Against Method he argued that scientific progress is not the result of applying any particular rules. Instead, he concluded almost that "anything goes", in that for any particular ‘rule’ there are abundant examples of successful science that have proceeded in a way that seems to contradict it. [2] To Feyeraband, there is no fundamental difference between science and other areas of human activity characterised by reasoned thought. A similar sentiment was expressed by T.H. Huxley in 1863: “The method of scientific investigation is nothing but the expression of the necessary mode or working of the human mind. It is simply the mode at which all phenomena are reasoned about, rendered precise and exact.” Nevertheless, in the Daubert v. Merrell Dow Pharmaceuticals, Inc. [509 U.S. 579 (1993)] decision, the U.S. Supreme Court accorded a legal status to ‘The Scientific Method ‘, in ruling that “… in order to qualify as ’scientific knowledge’ an inference or assertion must be derived by the scientific method. Proposed testimony must be supported by appropriate validation - i.e., ‘good grounds,’ based on what is known.” The Court also stated that “A new theory or explanation must generally survive a period of testing, review, and refinement before achieving scientific acceptance. This process does not merely reflect the scientific method, it is the scientific method.”

Hypotheses and theories

Hypotheses and theories play a central role in science; the idea that any observer can study the world except through the spectacles of his or her preconceptions and expectations is not sustainable. As these preconceptions change with progressively changing understanding of the world, the nature of science itself changes, and what was once considered conventionally scientific no longer seems so in retrospect.

A hypothesis is a proposed explanation of a phenomenon. It is an “inspired guess”, a “bold speculation” , embedded in current understanding yet going beyond that to assert something that we do not know for sure as a way of explaining something not otherwise accounted for. Scientists use many different means to generate hypotheses including their own creative imagination, ideas from other fields, induction, Bayesian inference. Charles Sanders Peirce described the incipient stages of inquiry, instigated by the "irritation of doubt" to venture a plausible guess, as abductive reasoning. The history of science is filled with stories of scientists claiming a "flash of inspiration", or a hunch, which then motivated them to look for evidence to support or refute their idea. Michael Polanyi made such creativity the centrepiece of his discussion of methodology.

The philosopher Karl Popper , in a book that Sir Peter Medawar called one of the most important documents of the 20th century, argued forcefully that argued that


He argued that the essential quality of a good hypothesis is that it must be falsifiable; it must be challengeable by experiments, and he argued that science is this process of challenging hypotheses by experiments, and that progress is made when a hypothesis resists determined attempts at disproof, and becomes provisionally accepted as a valuable tool for adding to our understanding. Conversely, he argued that a proposition or theory cannot be called scientific if it does not admit the possibility of being shown false. It must, at least in principle, be possible to make an observation that would show the proposition to be false, otherwise the proposition is vacuous, with, as Popper put it, no connection with the real world. For Popper therefore, explanations without any predictive content, and he argued that the explanations of Freudian psychoanalysis, those of Marxism, and those of astrology, were all examples of ‘empty’ unscientific theories.

For Popper, a theory was the context within which hypotheses are developed, and which determined which things were important to investigate and which were not. The theory encompasses the preconceptions by which the world is viewed, and defines the ways we study it and understand it. A theory thus has a profound importance, without a theory no science is possible. He thus recognised that you do not discard a theory lightly, and that a theory might be inconsistent with many known facts (anomalies). However, the recognition of anomalies drives scientists to elaborate or adjust the theory, and if the anomalies continue to accumulate, will drive them to develop alternative theories. He also explained that theories always contain many elements that are not falsifiable, but he argued that these should be kept to a minimum, and that the content of a theory should be judged by the extent to which it inspired testable hypotheses (although this is certainly not his only criterion). Scientists also seek theories that are "elegant" or "beautiful"; these terms are subjective and hard to define, but they express the scientists expectation that a theory should yield clear, simple explanations of complex phenomena, that are intellectually satisfying in the sense of appearing to be logically coherent, rich in content, and involving no miracles or other supernatural devices.


Popper thus argued that progress in science depends upon attempted falsification of hypotheses, and that most progress came by success in falsifying them; disproof is logically sound, support by induction is logically unsound. "Verifiability" in Popper's view was not the object or intent of science, just a weak by-product of a failed attempt at falsification.

The historian of science Thomas Kuhn maintains that the "route from theory to measurement can almost never be travelled backward"; which theory is tested is dictated by the nature of the theory itself. This led Kuhn to argue that "once it has been adopted by a profession ... no theory is recognized to be testable by any quantitative tests that it has not already passed".[3]


Experiments and observations

Werner Heisenberg in a quote that he attributed to Albert Einstein , stated [Heisenberg 1971]:

The phenomenon under observation produces certain events in our measuring apparatus. As a result, further processes take place in the apparatus, which eventually and by complicated paths produce sense impressions and help us to fix the effects in our consciousness. Along this whole path—from the phenomenon to its fixation in our consciousness—we must be able to tell how nature functions, must know the natural laws at least in practical terms, before we can claim to have observed anything at all. Only theory, that is, knowledge of natural laws, enables us to deduce the underlying phenomena from our sense impressions.

For a large part of the 20th century, the dominant approach to science has been reductionism – the attempt to explain all phenomena in terms of basic laws of physics and chemistry. In many fields, such explanations are very remote, and all explanations involve “high level” concepts, but the reductionist belief has been that these high level concepts are all ultimately reducible to physics and chemistry, and that the role of science is to progressively explain high level concepts by concepts closer and closer to the basic physics and chemistry. For example, to explain the behaviour of individuals we might refer to motivational states such as hunger or stress or anxiety. We believe that these reflect features of the activity of the brain that are still poorly understood, but can investigate the brain areas that house these motivational drives, calling them, for example, “hunger centres”, These centres each involve many neural networks – interconnected nerve cells, and the functions of each network we can again probe in more detail. These networks in turn are composed of specialised neurones, whose behaviour can be analysed individually. These specialised nerve cells have distinctive properties that are the product of a genetic program that is activated in development – and so reducible to molecular biology. However, while behaviour is in this sense reducible to basic elements, explanations in terms of these basic elements have at present little predictive value in general, because the uncertainties in our understanding are too great, so explanations of behaviour still largely depend upon the high level constructs. Historically, the converse philosophical position to reductionism has taken many names, but the clearest debate was between “vitalism” and reductionism. Vitalism held essentially that some features of living organisms, including life itself, were not amenable to a physico-chemical explanation, and so asserted that high level constructs were essential to understanding and explanation. Scientific measurements are usually tabulated, graphed, or mapped, and statistical analyses of them; often these representations of the data using tools and conventions that are at a given time, accepted and understood by scientists working within a given field. The measurements often require specialized instruments such as thermometers, microscopes, or voltmeters, whose properties and limitations are familiar to others in the field, and the progress of a scientific field is usually intimately tied to their development. Measurements also demand the use of operational definitions. A scientific quantity is defined precisely by how it is measured, in terms that enable other scientists to reproduce the measurements. In many cases, this ultimately involves internationally agreed ‘standards’. For example, electrical current, measured in amperes, can be defined in terms of the mass of silver deposited in a certain time on an electrode in an electrochemical device that is described in some detail. The scientific definition of a term sometimes differs substantially from their natural language usage. For example, mass and weight overlap in meaning in common use, but have different meanings in physics. Scientific quantities are often characterized by their units of measure which can later be described in terms of conventional physical units when communicating the work. Measurements are not reports of absolute truth, all measurements are accompanied by the possibility of error in measurement, so they are usually accompanied by estimates of their uncertainty, This is often estimated by making repeated measurements, and seeing by how much these differ. Counts of things, such as the number of people in a nation at a particular time, may also have an uncertainty due to limitations of the method used. Counts may only represent a sample of desired quantities, with an uncertainty that depends upon the sampling method used and the number of samples taken.

The scientific method in practice

The UK Research Charity Cancer UK gave an outline of the scientific method, as practised by their scientists [2]. The quotes that follow are all from this outline

‘’[Scientists] start by making an educated guess about what they think the answer might be, based on all the available evidence they have. This is known as forming an hypothesis. They then try to prove if their hypothesis is right or wrong. Researchers carry out carefully designed studies, often known as experiments, to test their hypothesis. They collect and record detailed information from the studies. They look carefully at the results to work out if their hypothesis is right or wrong…’’

Once predictions are made, they can be tested by experiments. If the outcome contradicts the predictions, then the hypotheses are called into question and explanations may be sought. Sometimes experiments are conducted incorrectly. If the results confirm the predictions, then the hypotheses are considered likely to be correct but might still be wrong and are subject to further testing. Scientists assume an attitude of openness and accountability on the part of those conducting an experiment. Detailed record keeping is essential, to provide evidence of the effectiveness and integrity of the procedure and to also assist in reproducing the experimental results. This tradition can be seen in the work of Hipparchus (190 BCE - 120 BCE), when determining a value for the precession of the Earth over 2100 years ago, and 1000 years before Al-Batani.

Peer review

‘’…Once they have completed their study, the researchers write up their results and conclusions. And they try to publish them as a paper in a scientific journal. Before the work can be published, it must be checked by a number of independent researchers who are experts in a relevant field. This process is called ‘peer review’, and involves scrutinising the research to see if there are any flaws that invalidate the results…’’

Manuscripts submitted for publication in scientific journals are normally sent by the editor to (usually one to three) fellow (usually anonymous) scientists who are familiar with the field for evaluation. The referees may or may not recommend publication, publication with suggested modifications, or, sometimes, publication in another journal. This helps to keep the scientific literature free of unscientific work, reduces obvious errors, and generally otherwise improve the quality of the scientific literature. The peer review process has been criticised, but has been very widely adopted by the scientific community.

Originality, importance and interest are particularly important in “high impact” journals - see for example the author guidelines for Nature. Criticisms (see Critical theory) of these restraints are that they are so nebulous in definition (e.g. "good scientific practice") and open to ideological, or even political, manipulation that they often serve to censor rather than promote scientific discovery. Apparent censorship through refusal to publish ideas unpopular with mainstream scientists (unpopular because of ideological reasons and/or because they seem to contradict long held scientific theories) has soured the popular perception of scientists as being neutral or seekers of truth and often denigrated popular perception of science.

The scientific literature

‘’…If the study is found to be good enough, the findings are published and acknowledged by the wider scientific community…’’

However Thomas Kuhn argued that scientists are

Sir Peter Medawar, Nobel laureate in Physiology and Medicinein his article “Is the scientific paper a fraud?” answered yes, “The scientific paper in its orthodox form does embody a totally mistaken conception, even a travesty, of the nature of scientific thought.” In scientific papers, the results of an experiment are interpreted only at the end, in the discussion section, giving the impression that those conclusions are drawn by induction or deduction from the reported evidence. Instead, explains Medawar, the expectations that a scientist begins with provide the incentive for the experiments, and determine their nature, and they determine which observations are relevant and which are not. Only in the light of these initial expectations that the activities described in a paper have any meaning at all. The expectation, the original hypothesis, according to Medawar, is not the product of inductive reasoning but of inspiration, educated guesswork. Medawar was echoing Karl Popper, who proclaimed that

Confirmation

‘’…But, it isn’t enough to prove a hypothesis once. Other researchers must also be able to repeat the study and produce the same results, if the hypothesis is to remain valid…’’

Sometimes experimenters make systematic errors during their experiments, Consequently, it is a common practice for other scientists to attempt to repeat experiments, especially experiments that have yielded unexpected results[4]. Accordingly, scientists keep detailed records of their experiments, to provide evidence of their effectiveness and integrity and assist in reproduction. However, it is not possible for a scientist to record everything that took place in an experiment. He must select the facts that he believes are relevant to the experiment. This may lead to problems if some supposedly irrelevant feature is questioned. For example, Heinrich Hertz did not report the size of the room that he used to test Maxwell's equations, and this turned out to account for a deviation in the results. The problem is that parts of the theory must be assumed in order to select and report the experimental conditions. Observations are thus sometimes described as being 'theory-laden'. It seems to be only very rarely that scientists falsify their results; any scientist who does so takes an enormous risk, because if the claim is important it is likely to be subjected to very detailed scrutiny, and the reputation of a scientist depends upon the credibility of his or her work. Nevertheless there have been many well publicised examples of scientific fraud, and some have blamed the insecurity of employment of scientists and the extreme pressure to win grant funding for these instances. Under Federal regulations as published in the Federal Register, vol 65, no. 235, December 6, 2000 “A finding of research misconduct requires that: There be a significant departure from accepted practices of the relevant research community; and The misconduct be committed intentionally, or knowingly, or recklessly; and The allegation be proven by a preponderance of evidence.” Honor in Science, published by Sigma Xi , quotes C.P. Snow (The Search, 1959):“The only ethical principle which has made science possible is that the truth shall be told all the time. If we do not penalise false statements made in error, we open up the way, don’t you see, for false statements by intention. And of course a false statement of fact, made deliberately, is the most serious crime a scientist can commit.” It goes on to say: “It is not sufficient for the scientist to admit that all human activity, including research, is liable to involve errors; he or she has a moral obligation to minimize the possibility of error by checking and rechecking the validity of the data and the conclusions that are drawn from the data.”

Statistics

‘’…If the initial study was carried out using a small number of samples or people, larger studies are also needed. This is to make sure the hypothesis remains valid for bigger group and isn't due to chance variation…’’

There is an important school of Bayesian statistics that seeks to provide a statistical basis for support by induction, and some areas of science use these approaches; but in much of science this approach is not tenable because of the difficulty of attaching a priori probabilities in any meaningful way to the alternative predicted outcomes of an experiment. Popper was a mathematical logician, and argued strongly against Bayesian approaches. Popper was interested in how "support" for a theory could be measures by quantifying the degree of corroborative support, he did not dismiss statistical approaches lightly and explored their utility in detail. But in appendix ix to The Logic he states: As to degree of corroboration, it is nothing but a measure of the degree to which hypothesis h has been tested...it must not be interpreted therefore as a degree of the rationality of our belief in the truth of h...rather it is a measure of the rationality of accepting, tentatively, a problematic guess

Progress in science

‘’…Over time, scientific opinion can change. This is because new technologies can allow us to re-examine old questions in greater detail.’’

General Relativity

Einstein's prediction (1907): Light bends in a gravitational field

Einstein's theory of General Relativity makes several specific predictions about the observable structure of space-time, such as a prediction that light bends in a gravitational field and that the amount of bending depends in a precise way on the strength of that gravitational field. Arthur Eddington's observations made during a 1919 solar eclipse supported General Relativity rather than Newtonian gravitation.


See Also

Models of scientific inquiry Pseudoscience


Notes and references

  1. ↑ Sagan C. The fine art of baloney detection. Parade Magazine, p 12­13, Feb 1, 1987.
  2. ↑ Feyerabend PK (1975) Against Method, Outline of an Anarchistic Theory of Knowledge Reprinted, Verso, London, UK, 1978
  3. ↑ Kuhn TS (1961) The Function of Measurement in Modern Physical Science ISIS 52:161–193
    • Kuhn TS (1962)The Structure of Scientific Revolutions, University of Chicago Press, Chicago, IL, 1962. 2nd edition 1970. 3rd edition 1996.
    • Kuhn TS (1977) The Essential Tension, Selected Studies in Scientific Tradition and Change, University of Chicago Press, Chicago, IL
  4. ↑ Georg Wilhelm Richmann was killed by lightning (1753) when attempting to replicate the 1752 kite experiment of Benjamin Franklin. See, e.g., Physics Today, Vol. 59, #1, p42. [1]


Further reading

  • The Keystones of Science project, sponsored by the journal Science, has selected a number of scientific articles from that journal and annotated them, illustrating how different parts of each article embody the scientific method. Here is an annotated example of the scientific method example.
  • Bacon, Francis Novum Organum (The New Organon), 1620. Bacon's work described many of the accepted principles, underscoring the importance of Theory, empirical results, data gathering, experiment, and independent corroboration.
  • Bauer HH, Scientific Literacy and the Myth of the Scientific Method, University of Illinois Press, Champaign, IL, 1992
  • Beveridge, William I. B., The Art of Scientific Investigation, Vintage/Alfred A. Knopf, 1957.
  • Bernstein RJ (1983) Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis, University of Pennsylvania Press, Philadelphia, PA
  • Dewey, John (1991) How We Think, D.C. Heath, Lexington, MA, 1910. Reprinted, Prometheus Books, Buffalo, NY
  • Heisenberg, Werner (1971) Physics and Beyond, Encounters and Conversations, A.J. Pomerans (trans.), Harper and Row, New York, NY pp.63–64
  • Latour, Bruno, Science in Action, How to Follow Scientists and Engineers through Society, Harvard University Press, Cambridge, MA, 1987.
  • McComas WF, ed. The Principle Elements of the Nature of Science: Dispelling the Myths, from The Nature of Science in Science Education, pp53-70, Kluwer Academic Publishers, Netherlands 1998.
  • Poincaré H (1905) Science and Hypothesis Eprint

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