The Nature of Scientific Explanation

Lecture Six. Use and Abuse of Analogy and Metaphor in Scientific Explanation

69 Lecture Six Use and Abuse of Analogy and Metaphor in Scientific Expl anation Aristotle observed that even the most abstract of thought is necessarily accompanied by a sensory image. This notion came to be expressed by the Scholastic dictum, “There can be no intellection without accompanying sensation.” The function of images in scientific explanation will be addressed, but the immediate focus of this lecture is the use of metaphor in communicating insight into natural phenomena. Models employed in the sciences are a kind of metaphor in which a familiar structure or mechanism is used as an analogy to interpret natural phenomena. Historians of science tell us that scientific models are often suggestive in the development of new theories and in the modification of existing ones. Niels Bøhr said of his own work that he could not understand anything unless he could make a model of it. In my school days, the Bøhr model of the atom was to be found in every science classroom. That model, of course, gave way as we learned more about atomic and subatomic structure. New models introduced us to electron orbits, quantum leaps, 70 Cultural Considerations and similar constructs. Maritain complained in his Philosophy of Nature that in the domain of mathematical physics it is sometimes difficult to distinguish fact from theory. Pierre Gassendi, an early-seventeenth-century mathematician and philosopher, cautioned: “It is not permitted to transfer into Physics something abstractly demonstrated in Geometry,” an admonition often forgotten . Myanna Lahsen, an anthropologist who spent several years interviewing staff at the National Center for Atmospheric Research, reports that a member of the staff once confided, “It is easy to get caught up in it: you start to believe that what happens in your model must be what happens in the real world. And often it is not true.”1 Yet even mathematical physics, though seemingly confined to the world of abstract necessity, must return to the empirical for confirmation. A physicist may formulate his findings in the language of laws and express these by means of equations , but he still thinks in terms of things that govern his work. From an Aristotelian point of view, every scientific explanation is necessarily a realistic explanation, not a nominalistic one. Even Kant, who separated the world of logic from the ontological, assigned to metaphysics the role of preventing the employment of reason beyond its limits. He conceded: “Intellectualia as objects serve only as modo cognoscendia for the sensitive dabilium.”2 Theoretical physicists who have had some training in classical philosophy readily identify themselves as Aristotelians. Mathematical description, they acknowledge, is not scientific explanation. Pursuing a point made above, it is clear that if the investigator himself sometimes fails to distinguish fact from theory, how much more difficult it is for the layman to do so. Popular accounts of scientific reports come laden with metaphor, often 1. Wall Street Journal, February 1, 2006, A-15. 2. Immanuel Kant, Fragments, 17:533, translated by Paul Bowman, edited by P. Guyer (Cambridge: Cambridge University Press, 2005), 13. Lecture Six: Analogy and Metaphor 71 colorful, but not helpful. We are puzzled by the metaphor, “wrinkle in space time,” and equally mystified when we hear someone speak of gravity as “warped space time.” We read of “anti-matter,” “drops of electricity,” “black holes,” “right- and left-handed spin of K-mesons,” “backward causation,” and “strong locality.” And I haven’t even mentioned “string theory.” What, if anything, is conveyed to the layman by these terms? When the concept “antimatter ” was first introduced, the news was reported in ominous terms on the front page of major newspapers across the country. One of my classmates was called upon by a reporter for Washington ’s Herald Tribune for an explanation. The upshot was that a graduate student in physics at the Catholic University was depicted as having refuted a prominent physicist at Berkeley. Of course he had done no such thing; he was merely unpacking a simile or metaphor. My friend endured quite a bit of ribbing from his colleagues , but within little more than a decade, he became chairman of the physics department at a major research university. We know the mischief that can be created through the improper use of terms such as “evolution,” “indeterminacy,” and “relativity.” In a given scientific community metaphor may be a shorthand way of referring to certain data, to a theory, or to a...