Aristotle's Theory of the Unity of Science (review)

This study by Malcolm Wilson seeks to establish four main points: (1) that Aristotle developed a set of principles which served to link discoveries made within one field of inquiry to other fields; (2) that the application of these principles—subordination, analogy, 'focality,' and 'cumulation'—reflected the view of scientific explanation set out in the Posterior Analytics; (3) that the frequency with which Aristotle used these principles to solve problems in his metaphysics, theology, psychology, and moral theory suggests that his philosophy enjoyed a greater degree of unity than has been recognized; and (4) that Aristotle developed this set of linking principles in order to achieve that degree of unity (or to prevent a "chaotic heap" of disciplines). While there are some grounds for skepticism with respect to point (4), there can be little doubt that Wilson succeeds on the first three fronts: he shows that these linking principles (or at least the three he considers at some length) represent an important and insufficiently appreciated aspect of Aristotle's account of scientific knowledge.

Wilson traces Aristotle's interest in the unity question to a set of problems generated by Plato's contention that groups of individuals are best understood in connection with the single universal character they all share. (The esteem accorded in the Republic to a "supreme science of the Good" betrays a similar preference for explanation at the highest level of universality.) Resisting these universalizing tendencies (and the idea of a "single super science"), Aristotle opted for a set of individual sciences distinguished by their subject genus, with each viewed as pre-eminent in its own domain.

But this response, we are to believe, posed a new difficulty: "the isolating force of the subject-genus was so powerful that additional techniques were required to provide for the legitimate causal and explanatory links between sciences and subject-genera" (3). Specifically, Aristotle's insistence that the premises of scientific demonstration contain only terms predicable of a subject essentially (or per se) and 'as such' (or qua a particular kind of being) threatened to produce a set of narrowly focused and unrelated disciplines. However, the principle of subordination enabled one to move from one science (e.g., mathematics) to a subordinate or derivative one (e.g., optics). The principle of analogy enabled one to link subjects in different genera (e.g., by noticing that wings and fins provided birds and fish with parallel means of locomotion). The principle of focality (adopting G. E. L. Owen's term 'focal meaning' for Aristotle's 'pros hen predication') enabled one to connect subjects from different genera when they enjoyed a per se relationship with a core or 'focal' subject (e.g., when one connects medical instruments, techniques, and practitioners with the central concept of the medical art). The principle of cumulation enabled one to draw relationships among entities linked logically and ontologically with one another (e.g., when one form of friendship presupposes another, or when one kind of soul presupposes the existence of other kinds of soul.) And by developing these linking principles Aristotle found a way for "each subject to be treated separately while still maintaining its place in the intelligible architecture of the world" (13).

Nevertheless, it would be one thing for Aristotle to employ a set of principles endowed with a certain unifying capacity, a second thing for him to have been interested in them simply because they possessed that capacity, and a third to suppose that he devised them for the specific purpose of tying together an otherwise disparate set of sciences. Near the conclusion of his study, Wilson speaks merely in terms of the principles' unifying capacities: "these techniques allow for the inclusion of relevant and necessary external causes . . ., focality . . . provides a flexible description of normal science in both its core and extended aspects," and "analogy...