Platonic Theory of Ideas

The Problem of False Belief.

It has been remarked that for Plato the real problem of the "theory of knowledge" is not knowledge but error, that for him the difficulty was to explain not why our judgments are sometimes true but why they are ever anything else. In Plato's time, the problem of "false belief" was, indeed, one of the main questions of controversy, forced to the front by the Sophists, who contended that there was no such thing, but that "belief" is always true,—true, that is to say, for the individual who entertains it. And it was in order to come to close quarters with the matter that the inquiry into the nature of non-being was undertaken in the Sophist. Having disposed of the paradoxical notion that non-being is mere nothingness, having shown that when we say that "S is not P" we do not mean that S is nothing at all, but only that it is something other than P, he was free to inquire whether this pervasive feature of otherness or difference does not in fact penetrate into language and belief, so as to render it possible for us to say and to think "what is not." It is shown that every significant assertion is compounded of a noun a.id a verb; also that it must be "of" or "about" something, have a subject, and be of a certain quality (rotor rts). Thus, for example, the assertions that "Theaetetus is sitting down" and "Theaetetus is now flying" are both about Theaetetus, but the quality of the first is that of being true and the quality of the second that of being false.

Obviously, then, some combinations of nouns and verbs are false. Now, thinking is a silent dialogue of the mind with itself ; and belief is the positive or negative determination of such think ing, which is sometimes accompanied by sensation, and then we call it "phantasy." Since, then, a false assertion is possible, it fol lows that false belief and false phantasy are equally possible. But a false belief is not a belief about nothing at all; it is a belief which assigns to something a characteristic other than that which does belong to it. As Taylor points out, this solution of the prob lem turns on distinguishing the use of "is" as the logical copula from the existential sense of "is"; and, in taking that step, Plato may fairly be said to have originated scientific logic.

The Aristotelian System.

In approaching the Aristotelian system from the point of view of Platonism, the first impression is that of its irreconcilable opposition. Aristotle (384-322 B.c.) unfolds his most characteristic views largely through hostile criti cism of Platonic doctrine. Yet, notwithstanding numerous differ ences in matters of detail, there is substantial' agreement in general spirit and in final result. For Aristotle, as for Plato, philosophical explanation of the world of nature consisted in connecting it with the world of absolute being. He fully recognised that the world

of generation stands in need of a principle which lies beyond it, and that the necessity for such a principle becomes manifest when we follow out the general lines of connection within the world of generation. But his contention was that nothing is gained by first placing over against the world of generation a duplication of its main features which, as distinct in kind, can furnish no explana tion of what is in the world of generation. In particular, the fact of change was altogether inexplicable by reference simply to immutable essences. To Aristotle, then, it appeared that the Platonic elbos was merely a product of thought, a generality, not an existent entity per se. It indicated a common element or at tribute of things, not a thing, since, in his judgment, no generality can be regarded as having substantive existence.

For Aristotle as for Plato true knowledge is knowledge of the universal and necessary; but for Aristotle, while the essence of knowledge is complete as lying in a sphere entirely its own, the essence of "things" must necessarily be in them and not in a region beyond them. Thus the Aristotelian conception of the world of reality is that of a connected and graduated scheme of being extending from the pure indeterminateness of what he called "first matter" (rrpc.;)-rn i'/X0) up to the completed actuality, the deity. Each concrete individual thing in nature, each TOSE n, is to be conceived as a ai/poXoP, a combination of matter (An) and form (EISos or ,uopcin)). Matter is the substratum (broK€1.,uEvoy) of all becoming, that which is to be determined ; form is that which determines, that which gives to matter qualities and properties, the intelligible essence of a thing, that which enables us to say what a thing is. We can distinguish these in thought, but in real existence they are never to be found in isolation. Or, using another pair of Aristotelian opposites, the whole realm of existence presents itself as a chain of occurrences in which each transition is from the potential to the actual, from Si/Pal-us to iz4p-yeta. These two terms, as the other two, are to be understood as strictly relative to each other. The sculptor's shapen block is, for example, rela tively to the finished statue a 6iniamts but relatively to the rock from which it was hewn it is an b4p-yeta.

Every stage, then, in the process of nature exhibits the actualisa tion of what potentially was prepared for it in the stage imme diately beneath. All the stages are knit together as exhibiting the ways in which development takes place; and the real subjects of change are individual things, the concrete ways in which the actualisation of what is potential can alone come about.