ソクラテスは諸事例にもとづいて定義を獲得すべきだと考えるか?

Abstract

In Plato's early definitional dialogues Socrates and his interlocutors often enumerate examples before definitions are proposed. But it is not clear whether Socrates regards them as useful data for a definition. This unclarity has given rise to a long-standing dispute: some scholars (those who tend to think examples must come first in Socratic definition) have proposed that Socrates' procedure for definition is a method of abstraction and generalization based on examples, while others (those who think the definition must come first) have claimed that he cannot know which examples are genuine (and so cannot use them as reliable data), because of his commitment to the following principle: (PD) If one fails to know the definition of F-ness, then one fails to know, for any x, that x is F (where ‘F-ness' stands for things, e.g. the good or justice, about which there is no agreement among people as to what it is, and ‘x' stands for anything that may possibly turn out to be F). Both the example- and the definition-prioritisers have some textual grounds for their claims, which create a perplexing puzzle: Socrates seems to appeal to examples before reaching a definition, but he also says that one cannot know which examples are genuine before acquiring a definition. This article attempts to solve this puzzle by carefully examining the relevant texts and, at the same time, offers a new understanding of Socrates' procedure for definition. Before turning to my own interpretation, I critically examine the sole solution that has been offered so far. According to this proposal (I shall call it the true belief theory), Socrates does not know which examples are genuine, but he and his interlocutors are able nevertheless to collect genuine examples because of the true belief they have. Against this line of interpretation, I argue that, if true belief, or the capacity for judging examples correctly, has a place at all in Socrates' procedure for definition, then not only will it be a mystery how such true belief will be acquired, but such belief will, despite Plato's claims to the contrary, already provide most of what would be achieved by an actual definition. These consequences, I argue, are unacceptable. I next propose my own solution to the problem. I first point out that there are different kinds of examples Socrates and his interlocutors mention before proposing a definition: (1a) F-ness as instantiated in a certain thing, action, or situation (e.g. the virtue of a man), (1b) a part or kind of F-ness (e.g. courage as a part of virtue), (2) a particular type of thing or action (e.g. being able to manage public affairs, which one might think is an example of virtue), (3) an individual action or thing (e.g. Pericles, who was thought to be virtuous by many people). I suggest that in the case of (1a) it is absurd, and in the case of (1b) it is implausible, to hold (PD); everyone knows that the virtue of a man is virtue, or that courage is a virtue, even if he or she does not know the definition of virtue. I shall propose to call (1a) and (1b)-obviously genuine examples of F-ness-‘instances', as distinguished from mere ‘examples' which can refer to any one of the four kinds described above, i.e. (1a), (1b), (2), and (3). I then undertake a close examination of Plato's text in order to show that it is exactly these ‘instances' that Socrates in the early definitional dialogues makes use of as reliable data for a definition. My conclusion is that Socrates is not committed to (PD), but to the following weaker principle: (PDweak) If one fails to know the definition of F-ness, then one fails to know, for any x, that x is F (where ‘F-ness' stands for things, e.g. the good or justice, about which there is no agreement among people as to what it is, and ‘x' stands for anything that is not an instance of F-ness but may nevertheless be an example of F-ness).

In the final section, I try to clarify how we should understand this procedure of Socrates' for definition, one that only makes use of instances as data, by contrasting it with a standard model of the method of abstraction and generalization, i.e. the Aristotelian method of induction as described in the Posterior Analytics II 13, 97b7-39. Instances as I understand these do not provide concrete information necessary for the method of abstraction to work; they merely indicate in what kind of things, actions, or situations F-ness will be found. But they provide the stimulus for bringing to mind what F-ness is, in two ways: (1) many instances taken together stimulate us to advance to a definition that is associated with a wide variety of cases, thereby keeping us away from incorrect definitions that are related to an unduly restricted range of cases, and (2) each single instance helps us connect F-ness with our own perceptual experience and so stumble upon a definition. On the basis of this observation, I suggest that Socrates' procedure for definition should be characterised as a method of association based on instances. Some example-prioritisers have supposed that Plato replaced Socrates' method of abstraction with a new method in the middle dialogues. But my characterization of Socrates' method makes it possible for us to understand the continuity of Plato's method in the early and middle dialogues; for Plato's theory of recollection robustly buttresses the Socratic method of association based on instances.