CHAPTER IV
THE SCIENTIFIC IMAGINATION
It is quite generally recognized that imagination is indispensable in all sciences; that without it we could only copy, repeat, imitate; that it is a stimulus driving us onward and launching us into the unknown. If there does exist a very widespread prejudice to the contrary—if many hold that scientific culture throttles imagination—we must look for the explanation of this view first, in the equivocation, pointed out several times, that makes the essence of the creative imagination consist of images, which are here most often replaced by abstractions or extracts of things—whence it results that the created work does not have the living forms of religion, of art, or even of mechanical invention; and then, in the rational requirements regulating the development of the creative faculty—it may not wander at will. In either case its end is determined, and in order to exist, i.e., in order to be accepted, the invention must become subject to preëstablished rules.
This variety of imagination being, after the esthetic form, the one that psychologists have best described, we may therefore be brief. A complete study of the subject, however, remains yet to be made. Indeed, we may remark that there is no "scientific imagination" in general, that its form must vary according to the nature of the science, and that, consequently, it really resolves itself into a certain number of genera and even of species. Whence arises the need of monographs, each one of which should be the work of a competent man.
No one will question that mathematicians have a way of thinking all their own; but even this is too general. The arithmetician, the algebraist, and more generally the analyst, in whom invention obtains in the most abstract form of discontinuous functions—symbols and their relations—cannot imagine like the geometrician. One may well speak of the ideal figures of geometry—the empirical origin of which is no longer anywhere contested—but we cannot escape from representing them as somehow in space. Does anyone think that Monge, the creator of descriptive geometry, who by his work has aided builders, architects, mechanics, stone cutters in their labors, could have the same type of imagination as the mathematician who has been given up all his life to the theory of number? Here, then, are at least two well-marked varieties, to say nothing of mixed forms. The physicist's imagination is necessarily more concrete; since he is incessantly obliged to refer to the data of sense or to that totality of visual, tactile, motor, acoustic, thermic, etc., representations that we term the "properties of matter." Our eye, says Tyndall, cannot see sound waves contract and dilate, but we construct them in thought—i.e., by means of visual images. The same remarks are true of chemists. The founders of the atomic theory certainly saw atoms, and pictured them in the mind's eye, and their arrangement in compound bodies. The complexity of the imagination increases still more in the geologist, the botanist, the zoologist; it approaches more and more, with its increasing details, to the level of perception. The physician, in whom science becomes also an art, has need of visual representations of the exterior and interior, microscopic and macroscopic, of the various forms of diseased conditions; auditory representations (auscultation); tactile representations (touch, reverberation, etc.); and let us also add that we are not speaking merely of diagnosis of diseases, which is a matter of reproductive imagination, but of the discovery of a new pathologic "entity," proven and made certain from the symptoms. Lastly, if we do not hesitate to give a very broad extension to the term "scientific," and apply it also to invention in social matters, we shall see that the latter is still more exacting, for one must represent to oneself not only the elements of the past and of the present, but in addition construct a picture of the future according to probable inductions and deductions.
It might be objected that the foregoing enumeration proves a great variety in the content of creative imagination but not in the imagination itself, and that nothing has proven that, under all these various aspects, there does not exist a so-called scientific imagination, that always remains identical. This position is untenable. For we have seen above[109] that there exists no creative instinct in general, no one mere indeterminate "creative power," but only wants that, in certain cases, excite novel combinations of images. The nature of the separable materials, then, is a factor of the first importance; it is determining, and indicates to the mind the direction in which it is turned, and all treason in this regard is paid for by aborted construction, by painful labor for some petty result. Invention, separated from what gives it body and soul, is nothing but a pure abstraction.
The monographs called for above would, then, be a not unneeded work. It is only from them collectively that the rôle of the imagination in the sciences could be completely shown, and we might by abstraction separate out the characters common to all varieties—the essential marks of this imaginative type.
Mathematics aside, all the sciences dealing with facts—from astronomy to sociology—suppose three moments, namely, observation, conjecture, verification. The first depends on external and internal sense, the second on the creative imagination, the third on rational operations, although the imagination is not entirely barred from it. In order to study its influence on scientific development, we shall study it (a) in the sciences in process of formation; (b) in the established sciences; (c) in the processes of verification.