History of scientific method

The history of scientific method is indivisible from the history of science itself.

Early empiricism and philosophy

The earliest known roots of the scientific method trace as far back as Imhotep (c. 2600 BC), who is credited as the orginal author of the Edwin Smith papyrus; though this work is believed to be based on earlier material as early as circa 3000 BC. The methods entailed in the Edwin Smith papyrus (circa 1600 BC), an ancient surgical textbook, reflect the basic components of the scientific method: examination, diagnosis, treatment and prognosis.^[1]

Though the Ebers papyrus (ca 1550 BC) mentions incantations and foul applications created to cast out diseased demons and other superstition, its writings also nevertheless contain 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.

Emergence of inductive method

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.

The scientific method in its modern form arguably developed in early Muslim philosophy, in particular, using experiments to distinguish between competing scientific theories, citation ("isnad"), peer review and open inquiry leading to development of consensus ("ijma" via "ijtihad"), and a general belief that knowledge reveals nature honestly. During the middle ages, Islamic philosophy developed and was often pivotal in scientific debates–key figures were usually scientists and philosophers.

The prominent Arab-Iranian Muslim scientist Alhazen used the scientific method to obtain the results in his book Optics. In particular, he performed experiments and used the scientific method to show that the intromission theory of vision supported by Aristotle was scientifically correct, and that the emission theory of vision supported by Ptolemy and Euclid was wrong.

In his enunciation of a 'method' in the 13th century Roger Bacon, under the tuition of Robert Grosseteste, was inspired by the writings of Muslim alchemists (particularly Alhazen's work), 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."

Preamble to scientific method

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.

Integrating deductive and inductive method

Attempts to systematize a scientific method were confronted in the mid-18th Century by the problem of induction, a positivist logic formulation which, in short, asserts that nothing can be known with certainty except what is actually observed. David Hume took empiricism to the skeptical extreme; among his positions was that there is no logical necessity that the future should resemble the past, thus we are unable to justify inductive reasoning itself by appealing to its past success. Hume's arguments, of course, came on the heels of many, many centuries of excessive speculation upon excessive speculation not grounded in empirical observation and testing. Although Hume's radically skeptical arguments were convincingly refuted and ultimately superceded by Immanuel Kant's Critique of Pure Reason in the late 18th Century, Hume's brilliantly formatted arguments continued to hold a strong lingering influence on the consciouness of the educated classes for the better part of the 19th Century. Thus the argument at the time tended to focus on whether or not the inductive method was valid.

In the late 19th Century, Charles Sanders Peirce proposed a schema that would turn out to have considerable influence in the further development of scientific method generally. Peirce's work quickly accelerated the progress on several fronts. Firstly, speaking in broader context in "How to Make Our Ideas Clear" (1878) [2], Peirce outlined an objectively verifiable method to test the truth of putative knowledge on a way that goes beyond mere foundational alternatives, focusing upon both Deduction and Induction. He thus placed induction and deduction in a complimentary rather than competitive context (the latter of which had been the primary trend at least since David Hume a century before). Secondly, and of more direct importance to scientific method, Peirce put forth the basic schema for hypotheis/testing that continues to prevail today. Extracting the theory of inquiry from its raw materials in classical logic, he refined it in parallel with the early development of symbolic logic to address the then-current problems in scientific reasoning. Peirce examined and articulated the three fundamental modes of reasoning that play a role in scientific inquiry today, the processes that are currently known as abductive, deductive, and inductive inference. Thirdly, he played a major role in the progress of symbolic logic itself-- indeed this was his primary specialty.

Karl Popper (1902-1994) is generally credited with providing a context for major improvements in scientific method in the mid-to-late 20th Century. Beginning in the 1930's and with increased vigor after World War II, he argued that a hypothesis must be falsifiable and, following Peirce and others, that science would best progress using deductive reasoning as its primary emphasis, known as critical rationalism. His astute formulations of logical procedure helped to reign in the exessive use of inductive speculation upon inductive speculation, and also helped to strengthen the conceptual foundation for today's peer review procedures.

Critics of Popper, chiefly Thomas Kuhn, Paul Feyerabend and Imre Lakatos, rejected the idea that there exists a single method that applies to all science and could account for its progress. Indeed most scientists would agree. There remain, nonetheless, certain core principles that are the foundation of scientific inquiry today. (see also: scientific method)

Current issues

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.

Later in the 20th century, methodological naturalism came to be accepted as central to the scientific method, partly in response to rise of creation science.

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.

See also

• Timeline of the history of scientific method