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The principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to demonstrate the truth or falseness of the hypothesis, and a conclusion that validates or modifies the hypothesis.
Strategies or uniform rules of procedure used in some scientific research with a measure of success. Scientific methods differ in generality, precision, and the extent to which they are scientifically justified. Thus, whereas the experimental method can in principle be used in all the sciences dealing with ascertainable facts, the various methods for measuring the electron charge are specific. The search for increasing quantitative precision involves the improvement or invention of special methods of measurement, also called techniques. All scientific methods are required to be compatible with confirmed scientific theories capable of explaining how the methods work. The most general of all the methods employed in science is called the scientific method.
The scientific method may be summarized as the following sequence of steps: identification of a knowledge problem; precise formulation or reformulation of the problem; examination of the background knowledge in a search for items that might help solve the problem; choice or invention of a tentative hypothesis that looks promising; conceptual test of the hypothesis, that is, checking whether it is compatible with the bulk of the existing knowledge on the matter; drawing some testable consequences of the hypothesis; design of an empirical (observational or experimental) test of the hypothesis or a consequence of it; actual empirical test of the hypothesis, involving a search for both favorable and unfavorable evidence (examples and counterexamples); critical examination and statistical processing of the data (for example, calculation of average error and elimination of outlying data); evaluation of the hypothesis in the light of its compatibility with both the background knowledge and the fresh empirical evidence; if the test results are inconclusive, design and performance of new tests, possibly using different special methods; if the test results are conclusive, acceptance, modification, or rejection of the hypothesis; if the hypothesis is acceptable, checking whether its acceptance forces some change (enrichment or correction) in the background knowledge; identifying and tackling new problems raised by the confirmed hypothesis; and repetition of the test and reexamination of its possible impact on existing knowledge.
The scientific method is not a recipe for making original discoveries or inventions; it does not prescribe the pathway that scientists must follow to attain success. The goal of the scientific method is to ascertain whether a hypothesis is true to some degree. Indeed, the nucleus of the scientific method is the confrontation of an idea (hypothesis) with the facts it refers to, regardless of the source of the idea in question. In sum, the scientific method is a means for checking hypotheses for truth rather than for finding facts or inventing ideas. See also Science.
For more information on scientific method, visit Britannica.com.
Methods for investigating the natural world were transformed in the early modern era, leading to a variety of approaches that emerged from diverse philosophical orientations. To call these diverse methodologies "scientific" is a convenience but one that entails anachronistic usage. The Latin word scientia, meaning, broadly, 'knowledge', has none of the methodological implications of the modern term science. Early modern investigators called themselves philosophers, natural philosophers, physicians, and experimental or mathematical philosophers rather than scientists. Methodological issues often were the focus of lively discussions and bitter disputes. By the end of the era, approaches to investigating the natural world had undergone profound changes that historians traditionally have called the "scientific revolution."
Aristotelianism
The predominant methodology inherited by early modern learned culture was Aristotelian. The writings of Aristotle became the basis of the medieval university curriculum and remained so well into the seventeenth century. For Aristotle, knowledge (epistēmē in Greek, scientia in Latin) was universal and necessary. The goal of natural philosophy was to grasp the principles and natures of natural substances and to understand their causes. The method was a logical one based on syllogistic reasoning. If A equals B and B equals C, then A equals C. The four Aristotelian causes comprised the material cause (what a thing is made of), the formal cause (what kind of thing it is), the efficient cause (what made it), and the final cause (its purpose or goal), this last being most important. Demonstration was a process whereby a syllogistic proof of an effect was constructed through an analysis of its causes.
In the mid-sixteenth century at the University of Padua, traditional Aristotelian logic began to provide a renewed methodological basis for investigating the natural world. The most important figure in this development was Jacopo Zabarella (1533–1598). Remaining within an Aristotelian framework, the new logic asked how investigators got from sense perception to demonstrable truth. They discussed "demonstrative regress, a logical technique permitting the scholar to reason from an observed effect (fact) to its proximate cause and then to reason back (regress) from the cause to the effect where the reasoning began" (Grendler, p. 263). These methodological explorations influenced Galileo and other investigators until the mid-seventeenth century when Aristotelianism itself declined in influence.
Humanism and Neoplatonism
Without replacing Aristotelianism, new approaches developed in the fifteenth and sixteenth centuries that emphasized particulars. Humanism was a broad intellectual movement that engaged in the reform of Latin and the rediscovery of ancient texts. Humanists criticized the logical approach of Scholasticism and often focused upon individuals in specific times and places, utilizing the dialogue and letter as literary forms that allowed the expression of individual points of view. They also studied and edited ancient texts, many of which became significant for the investigation of the natural world.
Renaissance Neoplatonism emerged as a result of this humanist textual work. A key figure is Marsilio Ficino (1433–1499), who during the second half of the fifteenth century translated and edited the writings of Plato, Neoplatonic philosophers such as Plotinus (205–270 C.E.), and the Hermetic corpus. The latter consisted of a group of writings actually dating from late antiquity that Ficino and his contemporaries believed were written before the time of Moses by one Hermes Trismegistus. They considered that the Hermetic corpus comprised a synopsis of ancient theology (prisca theologia). Ficino and his many successors in the sixteenth and seventeenth centuries believed in the reality of magic and in occult powers because they viewed the universe as a spiritual unity connected in all its various parts by sympathies and antipathies. The magus or magician could influence remote parts of the cosmos by manipulating these connections, and he or she did so to influence worldly matters, such as sickness and health. The operational aspects of Neoplatonic magical traditions may have influenced the development of experimentation, a methodology that entailed the active manipulation of the natural world.
Neoplatonic doctrines also influenced notions about experience and its role in investigating nature. One example entails the doctrine of signatures and illumination. In one version, that of the sixteenth-century physician Paracelsus (1493/94–1541), experience is framed by the biblical context of the Fall. Humans after their expulsion from paradise no longer had direct access to the Word of God or direct knowledge of the world of nature. Yet because God had put the light of nature (lumens naturalis) in them they could overcome their fallen state. The light of nature awakened in their minds, so they were able to see signs stamped on natural things. Directly experiencing such things, they could thereby see God's "signatures," which were external signs that pointed to the internal nature of things.
Medicine and Alchemy
Within the discipline of medicine, interest in particulars and a validation of individual experience developed in a variety of ways. In the fourteenth century a branch of medicine known as practica emerged that concerned the particulars of disease and treatments. By the sixteenth century the writings of the ancient physician Galen (129–c. 199 C.E.) had become widely influential, particularly with respect to his empirical orientation and his practice of dissecting animals. Human dissection was taken up as part of the medical curriculum in the late medieval universities. Initially dissections were carried out in formal, public settings in which a high-status, learned doctor stood on a podium to read an authoritative text on anatomy, while a low-status person performed the handwork of dissection. In his famous De Humani Corporis Fabrica (On the fabric of the human body) published in 1543, Andreas Vesalius (1514–1564) advocated hands-on dissection by the high-status physician as well as careful observation and the visual depiction of body parts. Vesalius criticized but was also indebted to Galen. His famous treatise is part of a rich tradition of anatomical study that continued through the eighteenth century. This tradition notably includes the experimental work of William Harvey (1578–1657) in the 1620s on the circulation of the blood.
Alchemy represents a distinct discipline that developed in early modern Europe after the medieval transmission of key texts from the Islamic world. Alchemists often undertook hands-on, laboratory operations entailing separations, distillations, and the like. In the seventeenth century alchemy and related fields developed genuine experimental procedures. Jean Baptiste van Helmont (1579–1644) carried out numerous careful determinations of specific weights of substances he produced in his laboratory. George Starkey (1627–1665) undertook thousands of experiments to discover a single method of changing all sulfurs into medicines. The laboratory experiments of Robert Boyle (1627–1691) were influenced by this work. Scholars have investigated these seventeenth-century developments in detail and have traced their influence on eighteenth-century chemists, such as Antoine Lavoisier (1743–1794). This scholarship has brought into question the traditional sharp distinction between early modern alchemy and modern chemistry.
Mechanical Arts
The mechanical arts entailed skilled craft work, including carpentry and weaving, but also arts that are now considered fine arts, such as painting and sculpture. The influence of artisanal craft values on early modern scientific methodology has been a longstanding topic of discussion in the history of science. The Viennese scholar and refugee Edgar Zilsel (1891–1944) argued that artisanal values that appreciated hands-on experience and craft work influenced the emergence of an experimental methodology in the seventeenth century. Subsequent scholarship has shown that the fifteenth- and sixteenth-century proliferation of writings on mechanical arts transformed the practical knowledge of the crafts into discursive subjects worthy of the attention of learned persons. Painters and other practitioners wrote books in which they articulated the value of practice and direct experience as crucial for obtaining knowledge of the natural world.
Mathematics and Mechanics
Practical problems in the mechanical arts increasingly came to be analyzed in mathematical terms. The ancient mathematician Archimedes (c. 287–212 B.C.E.), who had applied geometric analysis to problems of statics (the science of weights), came to be highly influential. In the sixteenth century Niccolò Tartaglia (1499–1557) published the first Latin treatises of Archimedes and also wrote books in which he mathematically analyzed practical problems, such as the trajectory of cannonballs. Later in the same century authors, such as the nobleman and patron of Galileo, Guidobaldo del Monte (1545–1607), wrote treatises on machines and mechanics in the context of theory and mathematics.
This sixteenth-century tradition preceded the development of the new science of motion developed by Galileo Galilei (1564–1642). Galileo worked out the mathematical kinematics of motion. Disregarding air resistance, he concluded that all bodies fall in uniformly accelerated motion and that velocity increases in proportion to time elapsed. He went on to deduce the mathematical results of this conclusion, for instance, that the distance increases in proportion to the square of time. Following Galileo, Christiaan Huygens (1629–1695) worked out the mathematics of the pendulum and of circular motion. Near the end of the seventeenth century, in Philosophiae Naturalis Principia Mathematica (1687; Mathematical principles of natural philosophy), Isaac Newton (1642–1727) created a system of terrestrial and celestial dynamics in which he demonstrated mathematically a large array of propositions concerning natural phenomena. In these and many other examples in the seventeenth and eighteenth centuries, the aim of natural and experimental philosophers was to describe motion by means of mathematics. This project was possible because of simultaneous developments within mathematics itself, culminating in the invention of calculus by Newton and by Gottfried Wilhelm Leibniz (1646–1716) at the end of the seventeenth century.
Instrumentation and Experimentation
During the sixteenth and seventeenth centuries the use of instruments to measure and investigate the natural world came to be increasingly important. The Danish nobleman Tycho Brahe (1546–1601) is considered the greatest observational astronomer before the invention of the telescope. For twenty years, from his Uraniborg observatory, Brahe made systematic observations of the moon, the planets, and other phenomena, such as the comet of 1577. He used these observations not only to correct and improve available data but to investigate and develop theories about the nature of the heavens and the structure of the cosmos.
Observational astronomy changed with the invention of the telescope. With this new instrument Galileo made detailed observations of the moon and the stars of the Milky Way. He further discovered the four moons of Jupiter (the Medicean Stars). In The Sidereal Messenger (1610) he described these discoveries with both text and drawings. Galileo's conclusions were by no means instantly accepted. He had to persuade his contemporaries that his instrument produced valid data, not optical illusions. Like Brahe and others of his predecessors, Galileo produced new data, but he also used that data to make novel claims about the nature of the cosmos.
Instruments and devices became especially significant in the seventeenth and eighteenth centuries. Among these devises were "philosophical" machines especially devised to investigate the natural world. A prominent example of such a philosophical machine was the air pump, used by Boyle to investigate the nature of air. The pump was difficult to build and to use. Nevertheless, it was key to a whole series of experiments concerning air carried out in the mid-seventeenth century.
In seventeenth-century England the notion of the reliable witness to experiments emerged. Such a witness was an honorable person, preferably a gentleman (therefore immune from the self-interest of the artisan), who could attest to the accuracy of the stated results of a given experiment. Valid experimental results came to be tied to the social requirements of gentlemanly honor. By the eighteenth century, however, learned visitors interested in natural philosophy who came to London often visited the shops of instrument makers to purchase instruments but also to discuss philosophical and experimental issues. By this time the instrument maker's shop had become a space for philosophical discourse, while the status of certain kinds of craft practitioners had risen.
The use of instruments to investigate nature had important methodological implications because it challenged the notion of Aristotelian common experience. For Aristotelians common experience was valid because all reasonable people without question agreed that a particular claim was true. In contrast, truth derived from experimentation, and instrumentation depended on the manipulation of a device that was only available to particular individuals. Such individuals had to have access to the device itself and had to possess particular skills to use it. Aristotelian common experience and seventeenth-century experiment represented opposing methodologies. Further the use of instrumentation to investigate nature challenged the Aristotelian separation of the categories of technē (material production and reasoning about that production) and epistēmē (certain knowledge of unchanging truths).
Baconian Empiricism and Natural History
The English jurist and philosopher Francis Bacon (1561–1626) proposed a new methodology that aimed to bring about a continuous flow of new facts about the natural world. Bacon's most significant methodological work was Instauratio Magna (1620–1626; The great instauration), which included Novum Organum (1620; New instrument). Bacon rejected syllogistic logic, pointing out that the premises of the syllogism could be in error. His own method entailed gathering a large amount of data on a variety of subjects and applying that data to the development of axioms. His goal was to account for the many particular things in nature in all its diversity. Yet his method entailed more than the simple collection of sense experiences, for Bacon believed the senses could deceive. Rather, in the creation of axioms he took into account the "maker's knowledge," that is, the presuppositions necessary for the fabrication of a thing. To gather data, Bacon proposed a cooperative effort to write "histories of the trades," detailed accounts of the essential operations of productive arts, such as silk textiles, mining, printing, papermaking, and agriculture, as well as "natural histories" on topics such as snakes, birds, and metals.
In the sixteenth and seventeenth centuries, particularly in Italy, natural history was the focus of growing interest. The creation of natural history collections by naturalists, such as Ulisse Aldrovandi (1522–1605) and Athanasius Kircher (1601–1680), and the intense study of the specimens in those collections became an important aspect of the investigation of nature. Museums became "laboratories of nature" (Findlen, p. 154), where investigations entailing testing, dissection, and distillation occurred. In some instances the collection of specimens was accompanied by the creation of detailed drawings based on careful observations. Collecting specimens, examining them, and having them drawn or painted became important modalities for the study of nature. Federico Cesi (1585–1630) and other members of the Academy of the Lincei, a scientific society founded in 1603, were particularly active in this form of investigation of the flora and fauna of Italy.
Descartes and the Mechanical Philosophy
The methodological writings of René Descartes (1596–1650) laid the foundations for the "mechanical philosophy." Descartes's famous dictum "Cogito ergo sum" ('I think therefore I am') is the basis for his notion that mind is a thinking substance and is to be excluded from the physical world entirely. That world, composed of particles of matter, is characterized by extension. These particles move only by virtue of mechanical necessity. Their motions produce all the variety of natural phenomena. Descartes eliminated spiritual or mental qualities from the material world, leaving the thinking subject (the "I" of the cogito) as the discoverer of the clear and certain truths of nature. That natural world, characterized by extension, is ordered by mathematical relationships. For Descartes certain knowledge could be obtained by applying mathematical rules to the world of nature.
Conclusion
Investigations of the rich methodological cornucopia that characterizes the early modern period have been guided by several general principles. First, early modern thought is studied on its own terms, not according to the values of modern scientific methodology. Second, the wide-ranging connections of methodological thought to contemporaneous language and meaning on the one hand and to social and cultural conditions on the other are being explored in depth. Finally, studies have followed the sources, whatever that content might be. As a result, natural history has taken its place beside physics. The doctrine of signatures has been studied as thoroughly as the laws of planetary motion. Such contextual approaches have greatly expanded knowledge of early modern methodologies for investigating the natural world.
Bibliography
Primary Sources
Aristotle. The Complete Works of Aristotle: The Revised Oxford Translation. Edited by Jonathan Barnes. 2 vols. Princeton, 1984.
Galilei, Galileo. Sidereus Nuncius; or, The Sidereal Messenger. Translated by Albert van Helden. Chicago, 1989. An English translation that reproduces all of Galileo's drawings. Contains an extensive and useful introduction and notes.
Newton, Isaac. The Principia: Mathematical Principles of Natural Philosophy. Translated by I. Bernard Cohen and Anne Whitman. Berkeley and Los Angeles, 1999. Translation of Principia, 3rd ed. (1726). The translation to use. Contains an extensive and useful guide by Cohen.
Secondary Sources
Applebaum, Wilbur, ed. Encyclopedia of the Scientific Revolution: From Copernicus to Newton. New York, 2000.
Bennett, James A. "Shopping for Instruments in Paris and London." In Merchants and Marvels: Commerce, Science, and Art in Early Modern Europe, edited by Pamela H. Smith and Paula Findlen, pp. 370–395. New York, 2002.
Bono, James J. The Word of God and the Languages of Man: Interpreting Nature in Early Modern Science and Medicine. Vol. 1, Ficino to Descartes. Madison, Wis., 1995.
Dear, Peter. Discipline and Experience: The Mathematical Way in the Scientific Revolution. Chicago, 1995.
Des Chene, Dennis. Spirits and Clocks: Machine and Organism in Descartes. Ithaca, 2001.
Findlen, Paula. Possessing Nature: Museums, Collecting, and Scientific Culture in Early Modern Italy. Berkeley and Los Angeles, 1994.
Freedberg, David. The Eye of the Lynx: Galileo, His Friends, and the Beginnings of Modern Natural History. Chicago, 2002.
Grant, Edward. The Foundations of Modern Science in the Middle Ages: Their Religious, Institutional, and Intellectual Contexts. Cambridge, U.K., 1996.
Grendler, Paul F. The Universities of the Italian Renaissance. Baltimore, 2002.
Lindberg, David C., and Robert S. Westman, eds. Reappraisals of the Scientific Revolution. Cambridge, U.K., 1990.
Long, Pamela O. Openness, Secrecy, Authorship: Technical Arts and the Culture of Knowledge from Antiquity to the Renaissance. Baltimore, 2001.
Newman, William R., and Lawrence M. Principe. Alchemy Tried in the Fire: Starkey, Boyle, and the Fate of Helmontian Chymistry. Chicago, 2002.
Pérez-Ramos, Antonio. Francis Bacon's Idea of Science and the Maker's Knowledge Tradition. Oxford, 1988.
Shapin, Steven, and Simon Schaffer. Leviathan and the Air-Pump: Hobbes, Boyle, and the Experimental Life. Princeton, 1985.
Siraisi, Nancy G. Medieval and Early Renaissance Medicine: An Introduction to Knowledge and Practice. Chicago, 1990.
Wallace, William A. Galileo's Logic of Discovery and Proof: The Background, Content, and Use of His Appropriated Treatises on Aristotle's Posterior Analytics. Dordrecht, 1992.
—PAMELA O. LONG
Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurable evidence subject to specific principles of reasoning,[1] the collection of data through observation and experimentation, and the formulation and testing of hypotheses.[2]
Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methodologies of knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies to test these hypotheses. These steps must be repeatable in order to predict dependably any future results. Theories that encompass wider domains of inquiry may bind many hypotheses together in a coherent structure. This in turn may help form new hypotheses or place groups of hypotheses into context.
Among other facets shared by the various fields of inquiry is the conviction that the process must be objective to reduce a biased interpretation of the results. Another basic expectation is to document, archive and share all data and methodology so it is available for careful scrutiny by other scientists, thereby allowing other researchers the opportunity to verify results by attempting to reproduce them. This practice, called full disclosure, also allows statistical measures of the reliability of these data to be established.
From Alhacen (Ibn Al-Haytham 965 – 1039, a pioneer of scientific method) to the present day, the emphasis has been on seeking truth: "Truth is sought for its own sake. And those who are engaged upon the quest for anything for its own sake are not interested in other things. Finding the truth is difficult, and the road to it is rough. ..." [3]
"How does light travel through transparent bodies? Light travels through transparent bodies in straight lines only. ... We have explained this exhaustively in our Book of Optics. But let us now mention something to prove this convincingly: the fact that light travels in straight lines is clearly observed in the lights which enter into dark rooms through holes. ... the entering light will be clearly observable in the dust which fills the air." -- Alhacen[4]
The conjecture that "Light travels through transparent bodies in straight lines only", was corroborated by Alhacen only after years of effort. His demonstration of the conjecture was to place a straight stick or a taut thread next to the light beam[5], to prove that light travels in a straight line.
Thus scientific method has been practiced by some for at least one thousand years. There are difficulties in a formulaic statement of method, however. As William Whewell (1794-1866) noted in his History of Inductive Science (1837) and in Philosophy of Inductive Science (1840), "invention, sagacity, genius" are required at every step in scientific method. It is not enough to base scientific method on experience alone[6]; multiple steps are needed in scientific method, ranging from our experience to our imagination, back and forth.
In the twentieth century, a hypothetico-deductive model for scientific method was formulated (For a more formal discussion, see below.):
This model underlies the scientific revolution. One thousand years ago, Alhacen demonstrated the importance of steps 1 and 4. Galileo (1638) also showed the importance of step 4 (also called Experiment) in Two New Sciences. One possible sequence in this model would be 1, 2, 3, 4. If the outcome of 4 holds, and 3 is not yet disproven, you may continue with 3, 4, 1, and so forth; but if the outcome of 4 shows 3 to be false, you will have go back to 2 and try to invent a new 2, deduce a new 3, look for 4, and so forth. Note that 2 can never be shown to be absolutely true by scientific method[7]; only that 2 can be shown to be absolutely false by scientific method. (This is what Einstein meant when he said "No amount of experimentation can ever prove me right; a single experiment can prove me wrong.")
In the twentieth century, Ludwik Fleck (1896-1961) and others found that we need to consider our experiences more carefully, because our experience may be biased, and that we need to be more exact when describing our experiences. These considerations are discussed below.
A belief need not be true (although a belief can be true, even if its origins were myth).[8]
Needham's Science and Civilisation in China uses the 'flying horse' image as an example of observation: in it, a horse's legs are depicted as splayed, when the stop-action picture by Eadweard Muybridge shows otherwise. Note that the moment that no hoof is touching the ground, the horse's legs are gathered together and are not splayed.
Earlier paintings depict the incorrect flying horse observation. This demonstrates Ludwik Fleck's caution that we see what we expect to observe, until shown otherwise; our beliefs will affect our observations (and therefore our subsequent actions). But repeated application of scientific method can help us solve our problems by exposing those parts of our beliefs which are false. A scientific community will have the same interests, which allows it to help solve problems together.
There are many ways of outlining the basic method shared by all fields of scientific inquiry. The following examples are typical classifications of the most important components of the method on which there is wide agreement in the scientific community and among philosophers of science. There are, however, disagreements about some aspects.
The following set of methodological elements and organization of procedures tends to be more characteristic of natural sciences and experimental psychology than of social sciences. In the social sciences mathematical and statistical methods of verification and hypotheses testing may be less stringent. Nonetheless the cycle of hypothesis, verification and formulation of new hypotheses will resemble the cycle described below.
Imre Lakatos and Thomas Kuhn had done extensive
work on the "theory laden" character of observation. Kuhn (1961) said 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 traveled backward". This 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".
Each element of a scientific method 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 elements above are often taught in the educational system.[21]
Scientific method is not a recipe: it requires intelligence, imagination, and creativity[22]. It is also 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 in any way refute or discount Newton's Principia. On the contrary, if the astronomically large, the vanishingly small, and the extremely fast are reduced out from Einstein's theories — all phenomena that Newton could not have observed — Newton's equations remain. Einstein's theories are expansions and refinements of Newton's theories, and observations that increase our confidence in them also increase our confidence in Newton's approximations to them.
A linearized, pragmatic scheme of the four points above is sometimes offered as a guideline for proceeding:[citation needed]
The iterative cycle inherent in this step-by-step methodology goes from point 3 to 6 back to 3 again.
While this schema outlines a typical hypothesis/testing method,[23] it should also be noted that a number of 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.
The "operational" model combines the concepts of factory-style processing, operational definition, and utility:
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 scientific method. Here is an annotated example of this scientific method example titled Microbial Genes in the Human Genome: Lateral Transfer or Gene Loss?.
Scientific method depends upon increasingly more sophisticated characterizations of subjects of the investigation. (The subjects can also be called unsolved problems or the unknowns). 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 subjects, this careful thought may also entail some definitions and observations; the observations often demand careful measurements 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 or biology. 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 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.
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-iridium kept in a laboratory in France.
The scientific definition of a term sometimes differs substantially from its natural language usage. For example, mass and weight overlap in meaning in common discourse, but have distinct meanings in mechanics. 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.
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-understood.[25] 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.
A hypothesis is a suggested explanation of a phenomenon, or alternately a reasoned proposal suggesting a possible correlation between or among a set of phenomena.
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 resources they have — their own creativity, ideas from other fields, induction, Bayesian inference, and so on — to imagine possible explanations for a phenomenon under study. Charles Sanders Peirce, borrowing a page from Aristotle (Prior Analytics, 2.25) 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.
Karl Popper, following others, developing and inverting the views of the Austrian logical positivists, has 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
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. Occam's Razor serves as a rule of thumb for making these determinations.
Any useful hypothesis will enable predictions, 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.
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.
The control is very important.
Once predictions are made, they can be tested by experiments. If test results contradict predictions, then the hypotheses are called into question and explanations may be sought. Sometimes experiments are conducted incorrectly and are at fault. 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.
Depending on the predictions, the experiments can have different shapes. It could be a classical experiment in a laboratory setting, a double-blind study or an archaeological 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 record keeping 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 (853 CE – 929 CE).
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.
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 experiment of Benjamin Franklin.[28]
To protect against bad science and fraudulent data, government research granting agencies like NSF and science journals like Nature and Science have a policy that researchers must archive their data and methods so other researchers can access it, test the data and methods and build on the research that has gone before. Scientific data archiving can be done at a number of national archives in the U.S. or in the World Data Center.
The classical model of scientific inquiry derives from Aristotle[29], who distinguished the forms of approximate and exact reasoning, set out the threefold scheme of abductive, deductive, and inductive inference, and also treated the compound forms such as reasoning by analogy.
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.[30]
Many subspecialties of applied logic and computer science, to name a few, artificial intelligence, machine learning, 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, hypothesis formation, logical deduction, and empirical testing. Some of these applications draw on measures of complexity from algorithmic information theory to guide the making of predictions from prior 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.
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. Philosophy of science looks at the underpinning logic of the scientific method, at what separates science from non-science, and the ethic that is implicit in science.
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 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 might work in such a way that rational application of the method would always result in agreement and understanding; a perfect method would arguably be algorithmic, and so not leave any room for rational agents to disagree. As with all philosophical topics, the search has been neither straightforward nor simple. Logical Positivist, empiricist, falsificationist, and other theories have claimed to give a definitive account of the logic of science, but each has in turn been criticized.
Thomas Samuel Kuhn examined the history of science in his The Structure of Scientific Revolutions, and found that the actual method used by scientists differed dramatically from the then-espoused method.
Paul Feyerabend similarly examined the history of science, and was led 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 the strong programme, a radical approach to the sociology of science.
In his 1958 book, Personal Knowledge, chemist and philosopher Michael Polanyi (1891-1976) criticized the common view that the scientific method is purely objective and generates objective knowledge. Polanyi cast this view as a misunderstanding of the scientific method and of the nature of scientific inquiry, generally. He argued that scientists do and must follow personal passions in appraising facts and in determining which scientific questions to investigate. He concluded that a structure of liberty is essential for the advancement of science - that the freedom to pursue science for its own sake is a prerequisite for the production of knowledge through peer review and the scientific method.
The postmodernist critiques of science have themselves been the subject of intense controversy and heated dialogue. This ongoing debate, known as the science wars, is the result of the conflicting values and assumptions held by the postmodernist and realist camps. Whereas postmodernists assert that scientific knowledge is simply another discourse and not representative of any form of fundamental truth, realists in the scientific community maintain that scientific knowledge does reveal real and fundamental truths about reality. Many books have been written by scientists which take on this problem and challenge the assertions of the postmodernists while defending science as a legitimate method of deriving truth.[31][32][33][34][35]
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.
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, especially if it undermines the establishment in the particular field, and at other times may be too permissive. Other drawbacks includes cronyism and favoritism. The peer review process is not always successful, but has been very widely adopted by the scientific community.
