The expression “scientific method” is problematic for several reasons. First, it suggests that there is a single and uniform method employed in all scientific disciplines. However, even a cursory examination of various scientific fields reveals that this is not the case. Secondly, it ignores the historical fact that the general conception of science, including its purported methodology, has undergone changes since ancient times. Finally, it seems to encompass everything that is included in the cognitive processes of science, while in fact there are radical differences between two aspects of scientific cognition: the varied ways in which hypotheses are formed versus the more structured ways in which hypotheses are evaluated.
During the early modern stages of the scientific revolution, three major theories of scientific method were proposed: the first was the experimental approach advocated and practiced by Galileo and Toricelli, the second was a kind of empirical induction advocated by Francis Bacon, the third was the radical skepticism together with theological assumptions employed by the French mathematician and philosopher René Descartes. In the actual history of science, the evolution of the experimental trend proved fruitful, while the trends initiated by Bacon and Descartes turned out to be largely fruitless in modern science (even though they led to interesting developments in philosophy).
It is generally agreed that there is no recipe for scientific discovery, even though there is some agreement about the requirements for evaluating investigations and explanations. To understand what kinds of requirements are ideally regnant, it is useful to note the contexts in which scientific explanations occur.
To begin with, in any scientific inquiry there is the investigator, or much more commonly a team of investigators, conducting the research. Second, there are facts or problems, which the researcher(s) seek to discover, identify, explain, predict, or control. This factual component may be generated by the researchers, from other sources (such as others in the scientific community), or induced by phenomena occurring in the natural or human world. Third, there are the symbols used to represent the facts together with the symbols (which logicians call “syncategormatic terms”) used to organize and manipulate the factual concepts of interest. Fourth, at any given time there is a system of generally accepted, seemingly well-supported, conceptual schemes (theories, laws, concepts, etc.) that serves as a framework within which the results of the research are expected to fit. Fifth, there are varied sources of information, such as journal articles, conferences, and personal communications. Sixth, there are various rules and procedures, which ideally indicate the necessary logical requirements for making transitions from the factual component to the theoretical component. Following the proposal of F. S. C. Northrup in The Logic of the Sciences and the Humanities, one may call these the epistemic correlations. Seventh, there are various evaluative criteria and related procedures that serve to distinguish between scientific and unscientific accounts, or to try to choose the best among competing scientific explanations. This component of the context of scientific investigations includes, but is not limited to, criteria intended to eliminate or minimize bias. All these criteria may be referred to as the cognitive criteria. Eighth, there is the scientific community, composed primarily of investigators engaged in related fields of exploration. It is this community that should ultimately determine whether an individual scientist, or team of scientists, has obeyed the scientific and logical requirements that they all ideally accept. Of course, there are other things that initiate, guide, encourage, hinder, or prevent scientific exploration, such as funding and moral, social, political, and religious influences. These, however, are not integral components of science itself; they are external impositions. Whether such external impositions are needed, or desirable, is another matter.
Because of their importance in guiding scientific enterprises, the cognitive criteria will now be considered in some detail. The first criteria to be noted are those we may call objectivity criteria, since they are intended to distinguish between idiosyncratic (subjective) and objective features of experience. What is ideally required, although not always possible in practice, is repeatability of observations, experiments, logical and mathematical operations, publicly accessible measurable data, and where possible, double-blind experimental conditions and other safeguards against bias and deceit. Such cognitive restrictions ideally lead to intersubjective agreement among competent colleagues.
Another group of criteria, partially overlapping the objectivity criteria, are those criteria that ideally lead to the identification and rejection of scientifically unacceptable accounts. One group is those accounts for which nothing could possibly count as evidence for or against them. Typical of such pseudoexplanationsare fatalistic doctrines. A second group of scientifically unacceptable accounts are those based solely upon gratuitous assumptions or intuitions. A third group of pseudoexplanations, which may seem superficially to be genuine scientific explanations, are those explanations which employ essentially mysterious obscurantist language. A fourth group of defective explanations is those which, other things being considered equal, assume more than needs to be assumed and thus violate the principle of parsimony. Fifth, some putative explanations should be rejected because they are discovered to be internally inconsistent. These five criteria, which serve to identify and discard such scientifically unacceptable accounts, as well as some additional considerations, one may refer to as the eliminative criteria.
Finally, there are criteria that guide scientists in evaluating and choosing among rival scientifically respectable explanatory accounts. These criteria may be referred to as the scientific hypotheses criteria. The logician Irving M. Copi in his Introduction to Logic gives one of the best expositions of such criteria. The first criterion is relevance, which insists that minimally from a logically adequate account it must be possible to deduce the fact(s) to be explained. This minimal requirement is, of course, met even by many unscientific explanations. A second criterion is what Copi calls testability. Testability requires that in addition to relevance, a plausible scientific hypothesis must make it possible to predict some other fact. Confirmations of such predicted facts cannot prove an account to be correct, although they can increase the likelihood of the account being correct. However, if predicted facts are disconfirmed, then either the account must be rejected or ad hoc assumptions must be introduced. The third criterion is compatibility with previously well-established hypotheses, which insists that ideally a scientific account should fit into the framework of accepted science. Fourth, there is the criterion which Copi calls predictive or explanatory power, by which he means the range of observable facts that can be inferred from the rival alternative scientific explanations. If other requirements are equally satisfied by rival hypotheses, but more facts can be deduced from one of them, then this one is preferable. The fifth is logical simplicity, sometimes also referred to as Occam’s Razor or the principle of parsimony, which recommends that if rival accounts satisfy the other requirements equally well, then the one making the fewest assumptions is to be preferred.
There are basic presuppositions that form the current dominant scientific worldview, that is, the beliefs about nature and human experience that scientists usually take for granted and which make much of both pure and applied science possible. One of the interesting things about modern science is that most of its predominant presuppositions are really only refined commonsense conceptions:
- In general, scientists take for granted the reality of space and time, even though in relativity theory they are treated as coordinates in space-time.
- Scientists also share with common sense a belief in the reality of the material world.
- Scientists also share with common sense the presupposition that matter (or matter-energy) is quantitative, that is, that matter exists in precise quantities specifiable in terms of conveniently selected units.
- Another basic presupposition of modern science is the belief that natural objects, including human phenomena, are interdependent, either causally or otherwise.
- Logically associated in seeking to understand things causally is the presupposition that, on the macroscopic level at least, nearby entities obey uniform, consistent laws.
- Modern science also presupposes that much of nature can be understood non-teleologically, that is, that much of the natural order, as well as kinds of natural disorder, can be understood and explained without introducing notions of conscious goalseeking purposes.
- A similar basic presupposition of modern science is that the universe is intelligible in strictly naturalistic terms. Supernatural beliefs play no role in studying and comprehending nature.
Given the interests of individual researchers or their teams together with their knowledge of problems and contributions of others in relevant fields, and guided by the cognitive criteria and presuppositions, various possible problems and solutions arise. These possibilities are hypotheses—creations of the scientific imagination as to what to expect if certain observations, experiments, calculations, or theoretical elaborations are carried out. Once these creative imaginings have occurred, two additional essential steps in scientific method ideally must occur.
First, researchers must deduce from a hypothesis what might serve as confirming evidence if the hypothesis is correct, or what might serve to refute it if it is not correct.
Second, when possible (and this is not always possible), researchers try to test the hypothesis by seeking the confirming or refuting evidence under controlled conditions that are open to replication and the possibility of intersubjective agreement in the scientific community.
Although this sounds simple and straightforward, in many cases the processes involved are actually very complicated and variable.
All of the disciplines concerned with understanding aspects of human social phenomena try to rely on dependable cognitive methods, however it is not feasible to suggest that they all succeed in meeting scientific standards. Therefore, the most one can do here is to present a kind of idealized model representing what is involved in the best of social studies.
First, the researchers try to determine the variables to be studied. Second, the investigators seek a hypothesis (a possible relationship between, or among, these variables). For example, if the variables are drug use, poverty, and crimes of certain kinds, what might be sought are possible connections among these variables, or a relationship between or among them. Third, the researchers try to construct a test by means of which changes in the variables can be measured to discover whether the hypothesized relationship among the variables is confirmed or disconfirmed. Fourth, the test is implemented and the results are measured and recorded. Fifth, frequently but not always, these results may be used to form generalizations and to suggest further research. Sixth, members of the scientific community critically assess the protocol employed and suggest further investigations and possibly other hypotheses to explain the findings.
Although the theoretical framework of science will probably undergo significant changes, the basic method of science involving deductions of testable consequences, which has proven to be superior to all rival alleged cognitive methods, will probably remain the same. With the ongoing pursuits of scientists, guided by the cognitive context of science, hypotheses will arise, testable consequences of these hypotheses will be inferred, evidence for and against will be sought, tentative but plausible conclusions will be reached, and these conclusions will form parts of the evolving and naturalistic scientific worldview.
Concomitant with this evolving worldview, there will be new applications that may radically alter the world of everyday life. What effects scientific developments will have on religion, on morality, on economic arrangements, on politics, or on international relations, remain to be seen.
- Hoover, K., & Donovan, T. (2001). The elements of social scientific thinking (7th ed.). Boston: Bedford and St. Martin’s Press.
- Sagan, C. (1993). The demon haunted world: Science as a candle in the dark. New York: Random House.