Empirical Science Empirical data and their theoretical interpretation

First are the empirical elements. The task of science is to explain actual events, processes, or phenomena in nature; and no system of theoretical ideas, technical terms, and mathematical procedures--or mathematical procedures alone--qualifies as scientific unless it comes to grips with those empirical facts at some point and in some way and helps to make them more intelligible. On the one hand, the facts in question may be discovered by using observational methods--i.e., by recording them as and when they occur naturally, without employing any special contrivances affecting their occurrence. This situation is, of course, the normal case in astronomy, in which the objects of study cannot be influenced or controlled. Alternatively, they may be discovered by using experimental methods--i.e., by devising special equipment or apparatus with the help of which those processes or phenomena are caused to occur on demand and under specially controlled conditions. In that case, the scientist can attack scientific problems--to use Kant's vivid metaphor--by "putting Nature to the question," as in much of physics and fundamental biology. Either way, a philosophical difficulty at once arises about the results of the scientist's empirical studies: for he must ask how such raw empirical facts can be sifted, stated, and described in a way that throws light on the scientist's own theoretical problems. Do all empirical facts whatever serve as raw material for science? Or is this true only of those that have been preselected for their theoretical relevance--or even, to some extent, reshaped to ensure it? Is a scientist concerned with every particular empirical event, as such, or only with general phenomena or regularities recognizable in those events? Different schools of philosophers treat this raw material in very different ways. In the second place, there are conceptual elements. Every science employs its own characteristic abstractions, terminology, and techniques of interpretation and explanation, which can be of very different kinds. They may be ideal types, as in gas theory and parts of sociology; conservation principles, as in dynamics and energetics; taxa, as in biological systematics; particles or constituents, as in genetics and subatomic physics; models or flow diagrams, as in econometric analysis. Such conceptual elements are the intellectual keys by which phenomena are made intelligible, and a most active philosophical debate has turned around the part they play in the interpretation of phenomena. If, for instance, the idea of particles or ultimate constituents of matter is regarded as a concept created by scientists for the purpose of their own theoretical analysis, can an independent existence then be claimed for such theoretical entities in the world of nature itself? Or must all such ideas be regarded as fictions or constructs for which the claim to reality goes no further than the paper on which the scientific explanations are written? Similarly, if the theoretical descriptions of nature arrived at in science are unavoidably idealized and abstract, does this imply that the necessity attaching to arguments in, say, theoretical physics is itself only an artifact, or by-product, of scientists' own procedures for interpreting phenomena? Or can one, after all, speak of natural events themselves as happening "of necessity"? Finally, every natural science includes also formal and mathematical elements or mathematical elements alone. These may be mathematical algorithms, or procedures of calculation, like those used in computational astronomy since Babylonian days, or like the computer programs that are their 20th-century counterparts; or geometrical constructions, as in certain branches of optics; or methods of graphical analysis, such as those used in handling statistical data; or the axiomatic systems by which, from classical times on, geometry and physics have been organized into formal schemata of propositions bound together by logical relations. Philosophers in the Platonic tradition give such formal elements special consideration, viewing as authentically intelligible only those theories the content of which can be presented explicitly in formal, and preferably in mathematical, systems of propositions. Theories of this kind alone are capable--as the seminal German logician Gottlob Frege expressed it--of employing "concepts in their pure form." Thus, 20th-century philosophers of science have devoted much time and effort to the question: How far, and on what conditions, can other branches of natural science (e.g., quantum mechanics or genetics) be cast in the same definitive, axiomatic form as classical mechanics and electrical theory? Or is this formal construction itself merely a human convenience, adopted to simplify the handling of the empirical data, which reveals nothing more about the underlying structure of nature itself? Each of these three groups of elements poses problems about which philosophers of science are still in deep disagreement; and these differences of view can usefully be illustrated by indicating the various approaches adopted by members of rival schools when discussing each of the groups. At one extreme can be cited philosophers of a radically Empiricist frame of mind, who regard it as important, above all, to emphasize the empirical foundations of scientific knowledge; for them, the raw facts of experience are primary and entitled to absolute respect. On this view, general theoretical principles have authentic scientific content only when interpreted as empirical generalizations about directly grasped empirical data; and, correspondingly, abstract theoretical entities must be understood as logical constructions from more fundamental elements that can be directly identified in empirical experience. (This belief, of course, was the basis of Mach's conclusion that submicroscopic atoms were merely intellectual fictions and derived their scientific meaning entirely from the macroscopic sense experiences that they were used to explain.) At the other extreme, philosophers of a fully Rationalist, or Cartesian, bent can be cited who reject the idea that raw empirical facts, in and of themselves, display any intelligible or law-governed relationships whatsoever--and still less any necessary ones. For them, as for Plato, the scientist's bare experience of nature is a disorganized aggregate, or flux, unless and until he is able to discover some rational structure or principles relating these disconnected facts to a larger, more intelligible whole. Rather than allow equal significance and authority to every passing occurrence, the scientist, on this view, must be highly selective in the observations to which he pays attention; indeed, the very function of a well-designed experiment is now to create phenomena that can illustrate the intelligible relationships that are the true concern of science and so deserve the status of scientifically authenticated facts. Both of these approaches, the Empiricist and the Rationalist, emphasize valid and important points; but, in their extreme forms, they give rise to difficulties that are probably insuperable. As to the Empiricist approach, the credentials of any scientific concept or theory certainly depend to a substantial extent on its basis in empirical experience. Indeed, much has been learned about statistics, the calculus of probabilities, and the design of scientific experiments from careful analysis of the procedures by which empirical data are actually handled, even before questions of theoretical interpretation were directly raised. Yet it is questionable whether sense impressions alone could ever serve as evidence for any scientific position, as Mach and the sense-data philosophers assumed. All genuine scientific observations, as Kant expressed it, have the form of judgments--i.e., are expressed in statements answering questions formulated beforehand. It is probably an exaggeration to insist that all legitimate theoretical statements in science must be related in a strictly deductive manner to the everyday empirical observations that they are used to explain; and it is a caricature to treat the explanatory power of theoretical laws and principles, as for example in physics, as no different in kind from that of such an elementary generalization as "All robins' eggs are greenish blue." As to the Rationalist approach, one of the chief tasks for philosophers of science is certainly to account for the rational interconnections that give scientific explanations their characteristic intelligibility. In this respect, such men as Descartes, Kant, and Hertz have deepened the philosopher's understanding of the scientific enterprise by obliging him to recognize the ways in which the intellectual organization of scientific theories rests on the scientist's own constructive activities, rather than on the specific facts. Yet, it would again be misleading to use this fact as an excuse for regarding physical theories--to echo a phrase of Einstein's--as entirely "free creations of the human mind." While the step from observations to theories does not rest on formal entailments alone, it would be an equally serious counter-exaggeration to suggest that theory construction is totally arbitrary or unconstrained by the imperative demands of the specific problems to be solved. The outstanding task for most philosophers of science is, accordingly, to find an acceptable middle way between the Rationalist and Empiricist extremes and thus to do justice both to the empirical foundations of theories and to their internal organization. The different emphases of philosophers commonly reflect, at most, differences in their substantive preoccupations. Those who are interested (as was Mill) in possible methods for developing the human or social sciences naturally place most stress on the empirical basis of scientific knowledge. Those who are familiar (as was Whewell) with the actual outcome of theory construction in established sciences, such as physics, naturally underscore the systematic coherence and structure of scientific understanding. Those who are concerned with the nature and validity of historical understanding (as Giambattista Vico was) likewise end by giving a very different account of certainty and necessity from those (like Descartes) whose ideal of scientific knowledge is a formal, mathematical one. If the philosopher comes to grips with the full complexity of the scientific enterprise, this approach can lead him to a more exact understanding of the varied intellectual problems of the natural and human sciences. Once it is recognized how different are the kinds of questions arising within such diverse fields as quantum electrodynamics and developmental biology, clinical neurology and historical sociology, the goal of formulating a single scientific method--with a universally appliable set of procedures and criteria for judging new theories or ideas in all fields of science--may come to appear a mirage. Yet the philosopher's legitimate insistence on generality has already helped to promote important extensions and integrations of man's scientific understanding. So again, he must now avoid taking too dogmatic a stand, either for or against complete generality, bearing in mind Kant's warning that the reason can hope to map its own proper boundaries only at the price of occasionally overstepping them.

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