Aquinas and Analogy

8. Analogy and Discovery

EIGHT ANALOGY AND DI SCOVERY One of the benefits of achieving clarity about the claim that 'analogy' itself is an analogous term is that we see that only one of the meanings of the term refers to analogous names. It follows that there is something quixotic in trying to make those other meanings of 'analogy' part of an interpretation of what Thomas means by analogous names. The primary meaning of 'analogy' or 'proportion ' has nothing to do with analogous naming; it signifies a determinate relation of one quantity to another. It would be an obvious mistake to try to make this a kind of analogous name. It would be equally mistaken to try to make the analogy or proportion of effect to cause a kind of analogous name. There are other meanings and uses of 'analogy' that must be distinguished from analogous naming, and we shall look at some of them in this chapter and the next. In this chapter, we shall be looking at knowledge from or by analogy , not exhaustively, but sufficiently to distinguish it from analogous naming. Although language expresses knowledge-we name as we know-the kind of knowledge that is expressed by analogous names does not seem to be inferential, as if an analogous name tracked a series of arguments or discoveries. 'Healthy' as common ANALOGY AND DISCOVERY 143 to animal, food, and urine is understood without any suggestion that one or the other of these analogates is grounds for knowing the others, in the sense of discovering them. Would we say, for example, that we understand what it means to call food healthy on an analogy with knowing what it means to call an animal healthy? In some sense, surely yes, in that we must invoke the latter in order to explain the former. This is to know a relation or a proportion of one thing to another, but is it to know from a relation or proportion? Knowledge from Analogy If the privileged example of an analogous name does not seem to suggest a device for discovery, there are instances in Aristotle and Thomas in which an analogy is a device for discovering something, where to say that one knows something on the basis of an analogy has a quite specific meaning. We find this in Aristotle's discussion of justice in Book Five of the Nicomachean Ethics. The Mean ofJustice If the unjust is a kind of inequality, the just must consist in equality -a mean between the more or less, since the unjust can be on the side of too much or too little. If then the unjust is unequal, the just is equal, as all men suppose it to be be, even apart from argument. And since the equal is intermediate, the just will be an intermediate. Now equality implies at least two things. The just, then, must be both intermediate and equal and relative (i.e. for certain persons ). (Nicomachaean Ethics, V, 3, 1131aI2-16) That is, there are two persons and two things, and the just is the establishment of an equality. The just involves four terms: "for the persons for whom it is in fact just are two, and the things in which it is manifested, the objects distributed, are two" (II3 IaI9-20). Person : person :: thing : thing. The just is established in a proportionality . . . . proportionalitas nihil aliud est quam aequalitas proportionis; cum scilicet aequalem proportionem habet hoc ad hoc, et illud ad illud. Proportio :09 GMT) PART TWO: ANALOGOUS NAMES autem nihil est aliud quam habitudo unius quantitatis ad aliam. Quantitas autem habet rationem mensurae: quae primo quidem invenitur in unitate numerali, et exinde derivatur ad omne genus quantitatis ... (In V Ethics, 5,939) Proportionality is nothing other than an equality of proportion, as when there is an equal proportion between this and this, and that and that. And proportion is nothing other than the relation of one quantity to another. Quantity has the note of measure, something first found in numerical unity and thence deriving to every kind of quantity. Unsurprisingly, we are now reminded of certain features of mathematical proportionality, and first that it is of two kinds, geometric and arithmetic. Let us set it forth schematically. I. Kinds of Proportionality I. Geometric: a similar proportion (double, triple, etc) a. Disjunctive: 8 : 4 :: 20 : 10 [four terms] b. Continuous: 8 : 4 :: 4 : 2 [three terms] Disjunctive geometric proportionality enables us to find the mean in distributive justice. 2. Arithmetic: exact numerical difference 9 : 7...