with a view to attaining practical ends, then its forms must apply here as well as anywhere. Logical terminology may therefore be assumed to be welcome to this field where judgments are formed, induction is made from certain facts to defined conceptions, and deductions are derived from principles or premises assumed. Speaking then in these terms we may say that the Pre-Socratics had three logical problems set for them: First, there was a demand for a predicate, or, in other words, for a theory of the world. Secondly, there was the need of ascertaining just what should be regarded as the subject, or, otherwise stated, just what it was that required explanation. Thirdly, there arose the necessity of discovering ways and means by which the theory could be predicated of the world and by which, in turn, the hypothesis erected could be made to account for the concrete experience of life: in terms of logic this problem is that of maintaining an efficient copula. It is not assumed that the sequence thus stated was historically observed without crossing and overlapping; but a survey of the history of the period will show that, in a general way, the logical requirements asserted themselves in this order.
1. Greek philosophy began its career with induction. We have already stated that the preconceptions with which it approached its task were the result of previous inductions, and indeed the epic and theogonic poetry of the Greeks abounds in thoughts indicative of the consciousness of all of these problems. Thus Homer is familiar with the notion that all things proceed from water,89 and that, when the human body decays, it resolves itself into earth and water.90 Other opinions might be enumerated, but they would add nothing to the purpose. When men began, in the spirit of philosophy, to theorize about the world, they assumed that it—the subject—was sufficiently known. Its existence was taken for granted, and that which engaged their attention was the problem of its meaning. What predicate—so we may formulate their question—should be given to the subject? It is noticeable that their induction was quite perfunctory. But such is always the case until there are rival theories competing for acceptance, and even then the impulse to gather up evidence derived from a wide field and assured by resort to experiment comes rather with the desire to test a hypothesis than to form it. It is the effort to verify that brings out details and also the negative instances. Hence we are not to blame Thales for rashness in making his generalization that all is Water. We do not know what indications led to this conclusion. Aristotle ventured a guess, but the motives assumed for Thales agree too well with those which weighed with Hippo to admit of ready acceptance.
Anaximander, feeling the need of deduction as a sequel to induction, found his predicate in the Infinite. We cannot now delay to inquire just what he meant by the term; but it is not unlikely that its very vagueness recommended it to a man of genius who caught enthusiastically at the skirts of knowledge. Anaximenes, having pushed verification somewhat farther and eliciting some negative instances, rejected water and the Infinite and inferred that all was air. His ἀρχή must have the quality of infinity, but, a copula having been found in the process of rarefaction and condensation, it must occupy a determinate place in the series of typical forms of existence. The logical significance of this thought will engage our attention later.
Meanwhile it may be well to note that thus far only one predicate has been offered by each philosopher. This is doubtless due to the preconception of the unity and homogeneity of the world, of which we have already made mention. Although at the beginning its significance was little realized, the conception was destined to play a prominent part in Greek thought. It may be regarded from different points of view not necessarily antagonistic. One may say, as indeed has oftentimes been said, that it was due to ignorance. Men did not know the complexity of the world, and hence declared its substance to be simple. Again, it may be affirmed that the assumption was merely the naïve reflex of the ethical postulate that we shall unify our experience and organize it for the realization of our ideals. While increased knowledge has multiplied the so-called chemical elements, physics knows nothing of their differences, and chemistry itself demands their reduction.
The extension and enlarged scope of homogeneity came in two ways: First, it presented itself by way of abstraction from the particular predicates that may be given to things. This was due to the operation of the fundamental assumption that the world must be intelligible. Thus, even in Anaximander, the world-ground takes no account of the diversity of things except in the negative way of providing that the contrariety of experience shall arise from it. We are therefore referred for our predicate to a somewhat behind concrete experience. The Pythagoreans fix upon a single aspect of things as the essential, and find the meaning of the world in mathematical relations. The Eleatics press the conception of homogeneity until it is reduced to identity. Identity means the absence of difference; hence, spatially considered, it requires the negation of a void and the indivisibility of the world; viewed temporally, it precludes the succession of different states and hence the possibility of change.
We thus reach the acute stage of the problem of the One and the Many. The One is here the predicate, the subject is the Many. The solution of the difficulty is the task of the copula, and we shall recur to the theme in due time. It may be well, however, at this point to draw attention to the fact that the One is not always identical with the predicate, nor the Many with the subject. In the rhythmic movement of erecting and verifying hypotheses the interest shifts and what was but now the predicate, by taking the place of the premises, comes to be regarded as the given from which the particular is to be derived or deduced. There is thus likewise a shift in the positions of existence and meaning. The subject, or the world, was first assumed as the given means with which to construct the predicate, its meaning; once the hypothesis has been erected, the direction of interest shifts back to the beginning, and in the process of verification or deduction the quondam predicate, now the premises, becomes the given, and the task set for thought is the derivation of fact. For the moment, or until the return to the world is accomplished, the One is the only real, the Manifold remains mere appearance.
The second form in which the sense of the homogeneity of the world embodies itself is not, like the first, static, but is altogether dynamic. That which makes the whole world kin is neither the presence nor the absence of a quality, but a principle. The law thus revealed is, therefore, not a matter of the predicate, but is the copula itself. Hence we must defer a fuller consideration of it for the present.
2. As has already been said, the inductive movement implies the deductive, and not only as something preceding or accompanying it, but as its inner meaning and ultimate purpose. So too it was with the earliest Greek thinkers. Their object in setting up a predicate was the derivation of the subject from it. In other words their ambition was to discover the ἀρχή from which the genesis of the world proceeds. But deduction is really a much more serious task than would at first appear to one who is familiar with the Aristotelian machinery of premises and middle terms. The business of deduction is to reveal the subject, and ordinarily the subject quite vanishes from view. Induction is rapid, but deduction lags far behind. It may require but a momentary flash of "insight" on the part of the physical philosopher to discover a principle; if it is really significant, inventors will be engaged for centuries in deducing from it applications to the needs of life by means of contrivances. Thus after ages we come to know more of the subject, which is thereby enriched. The contrivances are the representatives of the copula in practical affairs; in quasi-theoretical spheres they are the apparatus for experimentation. It has just been remarked that by the application of the principles to life it is enriched; in other words, it receives new meaning, and new meaning signifies a new predicate. Theory is at times painfully aware of the multitude of new predicates proposed; rarely does it realize that there has been created a new heaven and a new earth. Without the latter, the former would be absurd.
Men take very much for granted and regard almost every achievement as a matter of course. Hence they do not become aware of their changed position except as it reflects itself in new schemes and in a larger outlook. The subject receives only a summary glance to discover what new predicate shall be evolved. Hence, while there is in Greek philosophy a strongly marked deductive movement, the theoretical results to the subject are insignificant. Thales seems, indeed, to have had no means to offer for the derivation of the world, but he evidently had no doubt that it was possible.
