A DEFINITION OF SCIENCE* WILLIAM
T. RICHARDS, PRINCETON UNIVERSITY, PRINCETON, NEWJZRSEY
Almost every man of science since the time of Aristotle has tried his hand a t defining his profession, and a continuation of this practice must be without the least hope of originality. Since, however, the current English definition, due to Huxley, seems lacking both in conciseness and in philosophic perspective, another has been attempted. It is presented Science i s the systematic description of fihenomena. herewith: It is not necessary to pause here for a detailed discussion of the considerations leading to the choice of each word in this definition. I t should be clear that the term "phenomena," with its implication of reproducibility and of common experience, separates the physical sciences alike from the arts, and from some aspects of the psychical. Again, the word "description" patently suggests the necessity of a language for the expression of scientific generalizations; the language employed is conditioned by the nature and degree of development of each branch of science, mathematical statement being, of course, the common medium of the physical sciences. Finally, the qualifying adjective "systematic" serves to distinguish scientific statement from merely casual, if empirically substantiated, expression of experience. This definition can lay no claim to ultimacy, since it treats science as a dichotomy of object and sense data, and does not attempt t o resolve the psychophysical paradox. A simple definition from any other standpoint seems however impossible, since a t present it must be not only self-explained, hut also self-justified.' The aspect of this definition especially worthy of emphasis here is its duality. Science is shown to he compounded of two types of thought, induction and deduction. That these may have a close fundamental connection is quite possible--indeed, i t is difficult t o escape the conviction that the significance of any deductive expression is founded ultimately on experience. But in science it is possible to distinguish clearly between the two. A statement made deductively is verified subjectively, whereas an inductive statement depends on "objective" verification. Their obscure relationship is, in science, seldom even felt. Although the two methods of thought may thus he readily distinguished, they never occur separately in science. An inductive generalization always involves deduction in its expression. If, for instance, a series of physical measurements of finite accuracy agree within limit of experimental error * Adapted from the preface of a thesis submitted to the Department of Chemistry of Harvard University in May, 1924, in partial fulfilment of the requirements for the degree of Doctor of Philosophy. ' Perhaps the most brilliant contemporary example of a non-paradoxical definition of science is A. N. Whitehead's "The Concept of Nature," Cambridge University Press, 1919.
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with a simple function, they are described by the function with infinite precision. The treatment of observations necessary to formulate them as a generalization must therefore always mouldthem in a more accurate form than experience justifies. Conversely, of course, mathematical expression, which may be considered as "pure" deductive thought, is a t once circumscribed and stimulated by the necessity of describing phenomena. This definition of science brings out strongly, therefore, an aspect which is perhaps the most important single principle in its organization. In science the infinite precision of the deductive process must always compromise with the very great fallibility of the empirical, and no resulting structure, however subtle, elegant, and widely substantiated can justly be termed "Natural Law." The searcher for truth, in the absolute sense, will find in it only a dilemma between scepticism coupled with futility, and statement coupled with certain error. If philosophic analysis did not lead to this conclusion the history of science, with its perpetual pendulum-like' oscillation between hypotheses, each of which interprets conveniently some aspect of a subject but is inadequate for the description of another, would irresistibly suggest it. Progress is being made, since the amplitude of the oscillations is decreasing with time. It is inconceivable, but not perhaps impossible, that in the far distant future the "world equation" suggested by LaPlace, in which every cosmic variable is simultaneously defined, may be realized. Then, and then only, shall we have scientific truth, completing in our knowledge of the universe one aspect of the larger Truth which is the summation of our sense-data.
