Scientific methods or processes are considered fundamental to the scientific investigation and acquisition of new knowledge based upon physical evidence. Scientists use observations, hypotheses and deductions to propose explanations for natural phenomena in the form of theories. Predictions from these theories are tested by experiment. Any theory which is cogent enough to make predictions can then be tested reproducibly in this way. The method is commonly taken as the underlying logic of scientific practice. A scientific method is essentially an extremely cautious means of building a supportable, evidence-based understanding of our natural world.

History

The development of methods for scientific inquiry is indivisible from the development of science. The Edwin Smith Papyrus (circa 1600 BC), an ancient surgical textbook, details the examination, diagnosis, treatment, and prognosis of numerous ailments. [1] Although the Ebers papyrus (ca 1550 BC) contains incantations and foul applications created to cast out diseased demons and other superstition, there is evidence of traditional empiricism.

In Ancient Greece, towards the middle of the 5th century BC, some of the elements of a scientific tradition were already well established. In Protagoras (318d-f), Plato mentions the teaching of arithmetic, astronomy and geometry in schools. The philosophical ideas of this time were mostly freed from the constraints of everyday phenomena and common sense. This denial of reality as we experience it reaches an extreme in Parmenides who argued that the world is one and that change and subdivision do not exist.

Aristotle provided yet another of the ingredients of scientific tradition: empiricism. For Aristotle, the Platonic, universal ideal is to be found in particular things, what he calls the essence of things. Using the concept of essence, Aristotle reconciles abstract thought with observation. In Aristotelian science, we find the beginnings of a primitive inductive method, although one that is based on collections of objects rather than experimentation.

In his enunciation of a 'method' in the 13th century Roger Bacon, under the tuition of Robert Grosseteste, was inspired by the writings of Arab alchemists who had preserved and built upon Aristotle's portrait of induction. Bacon described a repeating cycle of observation, hypothesis, experimentation, and the need for independent verification. In the 17th century, Francis Bacon attempted to describe a rational procedure for establishing causation between phenomena. In the Novum Organum (published 1620), Bacon is at pains to tell us that scientific theories (or rather axioms) should remain as close to the facts as possible:

"The understanding must not therefore be supplied with wings, but rather hung with weights, to keep it from leaping and flying. Now this has never been done; when it is done, we may entertain better hopes of the sciences."
Bacon's method made progress "by successive steps not interrupted or broken, we rise from particulars to lesser axioms; and then to middle axioms, one above the other; and last of all to the most general". The lesser axioms in this case should be rooted in experience obtained under stringent experimental conditions, for "experience, when it wanders in its own track, is [...] mere groping in the dark". The middle axioms building on the lesser, are "the true and solid and living axioms, on which depend the affairs and fortunes of men". And, last of all, "those which are indeed the most general" which are "abstract and without solidity".

Bacon's aphorism nineteen (XIX, of Book One) criticizes the tendency to leap to conclusions:

"There are and can be only two ways of searching into and discovering truth. The one flies from the senses and particulars to the most general axioms, and from these principles, the truth of which it takes for settled and immovable, proceeds to judgment and to the discovery of middle axioms. And this way is now in fashion."
and advocates a more cautious approach

"The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all. This is the true way, but as yet untried."
In 1619, René Descartes began writing his first major treatise on proper scientific and philosophical thinking, the unfinished Rules for the Direction of the Mind. With this document, Descartes established the framework for a scientific method's guiding principles. The following quote from his 1637 treatise, Discourse on Method presents the four precepts that characterize a scientific method:

"The first was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgement than what was presented to my mind so clearly and distinctly as to exclude all ground of methodic doubt.
The second, to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution.
The third, to conduct my thoughts in such order that, by commencing with objects the simplest and easiest to know, I might ascend by little and little, and, as it were, step by step, to the knowledge of the more complex; assigning in thought a certain order even to those objects which in their own nature do not stand in a relation of antecedence and sequence.
And the last, in every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted."
Both Bacon and Descartes wanted to provide a firm foundation for scientific thought that avoided the deceptions of the mind and senses. Bacon envisaged that foundation as essentially physical and factual, whereas Descartes trusted to logic and mathematics.

Galileo Galilei combined quantitative experimentation and mathematical analysis, to permit the enunciation of general physical laws. Isaac Newton systematized these laws in the Principia, which became a model that other sciences sought to emulate. His four "rules of reasoning" are:

1. We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.
2. Therefore to the same natural effects we must, as far as possible, assign the same causes.
3. The qualities of bodies, which admit neither intension nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever.
4. In experimental philosophy we are to look upon propositions collected by general induction from phænomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phænomena occur, by which they may either be made more accurate, or liable to exceptions.

But Newton also left an admonition about a theory of everything:

"To explain all nature is too difficult a task for any one man or even for any one age. 'Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things."
Some methods of reasoning were systematized by John Stuart Mill's Canons, which are five explicit statements of what can be discarded and what can be kept while building a hypothesis. George Boole and William Stanley Jevons also wrote on the principles of reasoning.

These attempts to systematize a scientific method were faced with the Problem of induction, which points out that inductive reasoning is not logically valid. David Hume set the difficulty out in detail. Karl Popper, following others, argued that a hypothesis must be falsifiable. Difficulties with this have led to the rejection of the idea that there exists a single method that applies to all science, and that serves to distinguish science from non-science.

In the past century, some statistical methods have been developed, for reasoning in the face of uncertainty, as an outgrowth of statistical hypothesis testing for eliminating error, an echo of the program of Francis Bacon's Novum Organum.

The question of how science operates has importance well beyond scientific circles or the academic community. In the judicial system and in public policy controversies, for example, a study's deviation from accepted scientific practice is grounds for rejecting it as junk science or pseudoscience.

No recipe

The scientific method is not a recipe. It requires intelligence, imagination, and creativity. Human imagination is a marvellous thing that can span everything -- from what has happened to what could happen. The scientific method merely places constraints on the imagination by stating requirements for lines of reasoning, and then going on from there.

Elements of a scientific method

The essential elements of a scientific method are iterations and recursions of the following four steps:

1. Characterization (Quantification, observation and measurement)
2. Hypothesis (a theoretical, hypothetical explanation of the observations and measurements)
3. Prediction (logical deduction from the hypothesis)
4. Experiment (test of all of the above)

The above includes observation in steps one and four. Each step is subject to peer review for possible mistakes. These activities do not describe all that scientists do (see below) but apply mostly to experimental sciences (e.g., physics, chemistry). The steps above are often taught in education1.

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 science method. Here is one example, showing how a group of scientists disproved a claim about lateral gene transfer in the human genome.

DNA/example

Each step is illustrated by an example from the discovery of the structure of DNA:

1. DNA/characterization
2. DNA/hypothesis
3. DNA/prediction
4. DNA/experiment

The examples are continued in "Evaluation and interation" with DNA/iteration.

Characterization

A scientific method depends upon a careful characterization of the subject of the investigation. (The subject can also be called the problem or the unknown.) For example, Benjamin Franklin correctly characterized St. Elmo's fire as electrical in nature, but it has taken a long series of experiments and theory to establish this. While seeking the pertinent properties of the subject, this careful thought may also entail some definitions and observations; the observation often demands careful measurement and/or counting.

The systematic, careful collection of measurements or counts of relevant quantities is often the critical difference between pseudo-sciences, such as alchemy, and a science, such as chemistry. Scientific measurements taken are usually tabulated, graphed, or mapped, and statistical manipulations, such as correlation and regression, performed on 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 scientific instruments such as thermometers, spectroscopes, or voltmeters, and the progress of a scientific field is usually intimately tied to their invention and development.

Measurements demand the use of operational definitions of relevant quantities. That is, a scientific quantity is described or defined by how it is measured, as opposed to some more vague, inexact or "idealized" definition. For example, electrical current, measured in Amperes, may 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 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 are often used interchangeably 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 units when communicating the work.

Measurements in scientific work are also usually accompanied by estimates of their uncertainty. The uncertainty is often estimated by making repeated measurements of the desired quantity. 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.

New theories sometimes arise upon realizing that certain terms had not previously been sufficiently clearly defined. For example, Albert Einstein's first paper on relativity begins by defining simultaneity and the means for determining length. These ideas were skipped over by Isaac Newton with, "I do not define time, space, place and 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-understoodCri94. 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 precession of Mercury

Precession of the perihelion (very exaggerated)The characterization phase can require extended and extensive study, even centuries. It took thousands of years of measurements, from the Chaldean, Indian, Persian, Greek, Arabic and European astronomers, to record the precession of the planet Earth. Newton was able to condense these measurements into consequences of his laws of motion. But the perihelion of the 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 (on the order of 42.5 arc-seconds per century), was one of the pieces of evidence for Einstein's characterization of his theory of General Relativity. This consequence (a difference in the values for this precession of 42.5 arc-seconds per century) was known only after the Schwarzschild solution to the Einstein field equation was published in 1916.

DNA/characterization(1)

The history of the discovery of the structure of DNA is a classic example of the four stages of the scientific method: in 1950 it was known that genetic inheritance had a mathematical description, starting with the studies of Gregor Mendel. But the mechanism of the gene was unclear. Researchers in Bragg's laboratory at Cambridge University made X-ray diffraction pictures of various molecules, starting with crystals of salt, and proceeding to more complicated substances. Using clues which were 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.

Hypothesis development
A hypothesis is a suggested description of the subject.

Normally hypotheses have the form of a mathematical model. Sometimes, but not always, they can also be formulated as 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 statements, stating that every instance of the phenomenon has a particular characteristic.

Scientists are free to use whatever they can — their own creativity, ideas from other fields, induction, systematic guessing, Bayesian inference, etc. — to imagine possible explanations for a phenomenon under study. 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.

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

DNA/hypothesis(2)

For example, in the race to determine the structure of DNA, Francis Crick and James Watson hypothesized that this molecule had a helical structure: two intertwined spirals. But Linus Pauling was about to embark on serious study of the molecule; he was hypothesizing a triple helix.

Prediction from the hypothesis
Any useful hypothesis will enable predictions, by 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.

It is essential that the outcome be currently unknown. Only in this case does the eventuation increase the probability that the hypothesis be true. If the outcome is already known, it's called a consequence and should have already been considered while formulating the hypothesis.

If the predictions are not accessible by observation or experience, the hypothesis is not yet useful for the method, and must wait for others who might come afterward, and perhaps rekindle its line of reasoning. For example, a new technology or theory might make the necessary experiments feasible.

Halley's comet
The classic example was Edmund Halley's prediction of the year of return of Halley's comet which returned after his death.

General Relativity
Einstein's prediction (1907): Light bends in a gravitational fieldEinstein'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.

DNA/prediction(3)

When Watson and Crick hypothesized that DNA was a double helix, Francis Crick predicted that a X-ray diffraction image of DNA would show an X-shape.

Experiment
Once a prediction is made, it can be tested in an experiment. If the test results contradict the prediction, then the hypothesis under test is incorrect or incomplete and requires either revision or abandonment. If the results confirm the prediction, then the hypothesis is more likely to be correct but might still be wrong and is subject to further testing.

Depending on the prediction the experiment can have different shapes. It could be a classical experiment in a laboratory setting, a double-blind study or an archeological excavation. Even taking a plane from New York to Paris is an experiment which tests the aerodynamical hypotheses used for constructing the plane.

Scientists assume an attitude of openness and accountability on the part of those conducting an experiment. Detailed recordkeeping is essential, to aid in recording and reporting on the experimental results, and providing evidence of the effectiveness and integrity of the procedure. They will 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.

DNA/experiment(4)

When James Watson was sent to investigate what Rosalind Franklin had found in her X-ray diffraction images of DNA, he saw the X-shape which Crick had predicted for a helical structure.

Evaluation and iteration

Testing and improvement

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 re-define 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.

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.

Light

Light had long been supposed to be made of particles. Isaac Newton, and before him many of the Classical Greeks, was convinced it was so, but his light-is-particles account was overturned by evidence in favor of a wave theory of light suggested most notably in the early 1800s by Thomas Young, an English physician. Light as waves neatly explained the observed diffraction and interference of light when, to the contrary, the light-as-a-particle theory did not. The wave interpretation of light was widely held to be unassailably correct for most of the 19th century. Around the turn of the century, however, observations were made that a wave theory of light could not explain. This new set of observations could be accounted for by Max Planck's quantum theory (including the photoelectric effect and Brownian motion—both from Albert Einstein), but not by a wave theory of light, nor by a particle theory.

DNA/iteration

Watson was able to deduce the essential structure of DNA by concrete modelling of the physical shapes of the nucleotides which comprise it. He was guided by the bond lengths which had been deduced by Linus Pauling. In all of this, the nature of the chemical bond had been characterized by the theory of quantum mechanics. After James Watson and Francis Crick's breakthrough discovery, an entire field of study was legitimized

Verification

Ball lightningScience is a social enterprise, and scientific work will become accepted by the community only if they can be verified. 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 ball lightning to his forehead (1753) when attempting to replicate the 1752 kite experiment of Benjamin Franklin.

Scope and goals

The scientific method can be applied to anything within the range of our experiences. As long as something has an impact on our lives we can formulate theories and try to predict, what this impact might be. The impact itself is an experiment, testing whether our theory was right. It can also be applied, starting with step four or step three, to theories coming from different sources than the scientific method itself, as long as those make prediction, or it is possible to deduce some.

People use this method all the time. They have theories about devices and make predictions how those will react to their actions. If a device does not work as expected the experiment disproves their theory. If they adjust their theory they are applying the scientific method, if they nevertheless stick to their theory they don't.

The scientific method doesn't aim at giving an ultimate answer. It's iterative and recursive nature implies, that it will never come to an end. So any answer it gives is a provisional answer. Hence it can't prove or verify anything in a strong sense. But if a theory passed many experimental tests without being disproved, it is considered superior to any theory, which has not yet been put to a test.

Scientific community

Frequently the scientific method is not employed by a single person, but by several people 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 scientists' 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 serves to keep the scientific literature free of unscientific or crackpot work, helps to cut down on obvious errors, and generally otherwise improve the quality of the scientific literature. Work announced in the popular press before going through this process is generally frowned upon. Sometimes peer review inhibits the circulation of unorthodox work, and at other times may be too permissive. The peer review process is not always successful, but has been very widely adopted by the scientific community.

Reproduction and Recordkeeping

Sometimes experimentators 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, experimentators are expected to maintain detailed records of their experimental procedures, in order 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.

Philosophical issues
The study of a scientific method is distinct from the practice of science and is more a part of the philosophy, history and sociology of science than of science. While such studies have limited direct impact on day-to-day scientific practice, they have a vital role in justifying and defending the scientific approach.

We find ourselves in a world that is not directly understandable. We find that we sometimes disagree with others as to the facts of the things we see in the world around us, and we find that there are things in the world that sometimes are at odds with our present understanding. The scientific method attempts to provide a way in which we can reach agreement and understanding. A perfect scientific method would work in such a way that rational application of the method would always result in agreement and understanding; in effect a perfect method would not leave any room for rational agents to disagree. Philosophers of science have long sought such a method. The material presented below is intended to show that, as with all philosophical topics, the search has been neither straightforward nor simple.

Theory-dependence of observation

A scientific method depends on observation, in defining the subject under investigation and in performing experiments.

Observation involves perception, and so is a cognitive process. That is, one does not make an observation passively, but is actively involved in distinguishing the thing being observed from surrounding sensory data. Therefore, observations depend on some underlying understanding of the way in which the world functions, and that understanding may influence what is perceived, noticed, or deemed worthy of consideration. (See the Sapir-Whorf hypothesis for an early version of this understanding of the impact of cultural artifacts on our perceptions of the world.)

Empirical observation is supposedly used to determine the acceptability of some hypothesis within a theory. When someone claims to have made an observation, it is reasonable to ask them to justify their claim. Such a justification must make reference to the theory - operational definitions and hypotheses - in which the observation is embedded. That is, the observation is a component of the theory that also contains the hypothesis it either verifies or falsifies. But this means that the observation cannot serve as a neutral arbiter between competing hypotheses. Observation could only do this "neutrally" if it were independent of the theory.

Thomas Kuhn denied that it is ever possible to isolate the theory being tested from the influence of the theory in which the observations are grounded. He argued that observations always rely on a specific paradigm, and that it is not possible to evaluate competing paradigms independently. By "paradigm" he meant, essentially, a logically consistent "portrait" of the world, one that involves no logical contradictions. More than one such logically consistent construct can each paint a usable likeness of the world, but it is pointless to pit them against each other, theory against theory. Neither is a standard by which the other can be judged. Instead, the question is which "portrait" is judged by some set of people to promise the most in terms of “puzzle solving”.

For Kuhn, the choice of paradigm was sustained by, but not ultimately determined by, logical processes. The individual's choice between paradigms involves setting two or more “portraits" against the world and deciding which likeness is most promising. In the case of a general acceptance of one paradigm or another, Kuhn believed that it represented the consensus of the community of scientists. Acceptance or rejection of some paradigm is, he argued, more a social than a logical process.

That observation is embedded in theory does not mean that observations are irrelevant to science. Scientific understanding derives from observation, but the acceptance of scientific statements is dependent on the related theoretical background or paradigm as well as on observation. Coherentism and scepticism offer alternatives to foundationalism for dealing with the difficulty of grounding scientific theories in something more than observations.

Indeterminacy of theory under empirical testing

The Quine-Duhem thesis points out that any theory can be made compatible with any empirical observation by the addition of suitable ad hoc hypotheses. This is analogous to the way in which an infinite number of curves can be drawn through any set of data points on a graph.

This thesis was accepted by Karl Popper, leading him to reject naïve falsification in favour of 'survival of the fittest', or most falsifiable, of scientific theories. In Popper's view, any hypothesis that does not make testable predictions is simply not science. Such a hypothesis may be useful or valuable, but it cannot be said to be science. Confirmation holism, developed by W. V. Quine, states that empirical data is not sufficient to make a judgement between theories. A theory can always be made to fit with the available empirical data.

That empirical evidence does not serve to determine between alternate theories does not imply that all theories are of equal value. Rather than pretending to use a universally applicable methodological principle, the scientist is making a personal choice when she chooses some particular theory over another.

One result of this is that specialists in the philosophy of science stress the requirement that observations made for the purposes of science be restricted to intersubjective objects. That is, science is restricted to those areas where there is general agreement on the nature of the observations involved. It is comparatively easy to agree on observations of physical phenomena, harder for them to agree on observations of social or mental phenomena, and difficult in the extreme to reach agreement on matters of theology or ethics.

Demarcation

Scientific Method is considered as one way of determining which disciplines are scientific and which are not. Those which follow a scientific method might be considered sciences; those that do not are not. That is, method might be used as the criterion of demarcation between science and non-science. If it is not possible to articulate a definitive method, then it may also not be possible to articulate a definitive distinction between science and non-science, between science and pseudo-science, and between scientists and non-scientists.

Feyerabend denies there is a scientific method, and in his book Against Method argues that scientific progress is not the result of the application of any particular method. In essence, he says that anything goes.

Science as a communal activity

In his book The Structure of Scientific Revolutions Kuhn argues that the process of observation and evaluation take place within a paradigm. 'A paradigm is what the members of a community of scientists share, and, conversely, a scientific community consists of men who share a paradigm' (postscript, part 1). On this account, science can be done only as a part of a community, and is inherently a communal activity.

For Kuhn the fundamental difference between science and other disciplines is in the way in which the communities function. Others, especially Feyerabend and some post-modernist thinkers, have argued that there is insufficient difference between social practices in science and other disciplines to maintain this distinction. It is apparent that social factors play an important and direct role in scientific method, but that they do not serve to differentiate science from other disciplines. Furthermore, although on this account science is socially constructed, it does not follow that reality is a social construct. Kuhn’s ideas are equally applicable to both realist and anti-realist ontologies.

The definition of a scientific method is debatable and contended. Positivist, empiricist, and falsificationist theories are unable to satisfy their aim of giving a definitive account of the logic of science. The sociology of science may be incapable of accounting for the success of the scientific enterprise.

Scientific thought

Carl Sagan, in his book The Demon-Haunted World, argues that we should use a scientific method as a tool for skeptical thinking. When we are presented with a new concept — ESP, for example — we should test the claims of its proponents against experiment ourselves (or gather evidence from as many sources as possible), and reject the theory if the evidence shows its claims to be false. Sagan was particularly interested in those movements which misrepresent science - pseudoscience or quackery.

Scientific method and the practice of science

The primary constraints on science are:

1. Publication, i.e. Peer review
2. Resources (mostly, funding)

It has not always been like this: in the old days of the "gentleman scientist" funding (and to a lesser extent publication) were far weaker constraints.

Both of these constraints indirectly bring in a scientific method — 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 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 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.

Quotations

"The scientific approach to the examination of phenomena is a defense against the pure emotion of fear." Tom Stoppard, Rosencrantz & Guildenstern Are Dead (1967, page 17 in Grove edition)