We turn now to the philosophical objections that may be raised to vitalistic speculations; and here we must be careful to distinguish what we may term the psychological from the metaphysical form of the theory.
Driesch has maintained that the belief in a morphaesthetic psychoid finds support in the philosophies of Kant and Aristotle. Let us examine the merits of this claim.
Like the scientists of to-day, Kant, in his Critique of the Teleological Judgement, lays it down as a rule that the mechanical method, by which natural phenomena are brought under general laws of causation and so explained, should in all cases be pushed as far as it will go, for this is a principle of the determinant judgement. There are cases, however, in which this alone does not suffice. The possibility of the growth and nutrition, above all of the reproduction and regeneration of organisms, is only fully intelligible through another quite distinct kind of causality, their purposiveness. Organisms are not mere machines, for these have simply moving power. Organisms possess in themselves formative power of a self-propagating kind, which they communicate to their materials. They are, in fact, natural purposes, both cause and effect of themselves, in which the parts so combine that they are reciprocally both end and means, existing not only by means of one another but for the sake of one another and the whole. The whole is thus an end which determines the process, a final cause which brings together the required matter, modifies it, forms it, and puts it in its appropriate place. Such purposiveness is internal, for the organism is at once its own cause and an end to itself, not merely a means to other ends, like a machine whose purposiveness is relative and whose cause is external.
Such is the principle of the teleological judgement. It is a heuristic principle rightly brought to bear, at least problematically, upon the investigation of organic nature, by a distant analogy with our own causality according to purposes generally, and indispensable to us, as anatomists, as a guiding thread if we wish to learn how to cognize the constitution of organisms without aspiring to an investigation into their first origin.
Could our cognitive faculties rest content with this maxim of the reflective judgement it would be impossible for them to conceive of the production of these things in any other fashion than by attributing them to a cause working by design, to a Being which would be productive in a way analogous to the causality of intelligence. Natural science, however, needs not merely reflective but determinant principles which alone can inform us of the possibility of finding the ultimate explanation of the world of organisms in a causal combination for which an understanding is not explicitly assumed, since the principle of purposes does not make the mode of origination of organic beings any more comprehensible. And then, in a passage remarkable for its prophetic insight, Kant proceeds to show how this might be. This ‘analogy of forms’, he says, ‘which with all their difference seem to have been produced according to a common original type, strengthens our suspicion of an actual relationship between them in their production from a common parent, through the gradual approximation of one genus to another—from those in which the principle of purposes seems to be best authenticated, that is from man down to the polype, and again from this down to mosses and lichens, and finally to the lowest stage of nature noticeable by us, namely, crude matter’. And so the whole technic of nature, which is so incomprehensible to us in organized beings that we believe ourselves compelled to think a different principle for it, seems to be derived from matter and its powers according to mechanical laws like those by which it operates in the formation of crystals. A purposiveness must, however, be attributed even to the crude matter, otherwise it would not be possible to think the purposive form of animals and plants.
Although there are doubtless in the Critique many obscurities and inconsistencies, to which we cannot allude now, the general meaning of Kant’s reflections upon organisms is perfectly clear. He who would ‘complete the perfect round’ of his knowledge must think not only in beginnings but in ends. The end in the case of a living being is apparently plain—it is the maintenance and reproduction of its form; the end in the case of the cosmic process is to be sought in the ethical, or, in Kantian phraseology, the ‘practical’ concept of the freedom of the moral consciousness of man.
Such a position is quite intelligible, philosophically, but the testimony it brings to the theory of the psychoid is of very doubtful value, as Driesch is well aware. He complains indeed that Kant’s teleology is descriptive or ‘static’, rather than ‘dynamic’, as is perfectly true, except in the case of man, a point of which Driesch naturally makes the most. There are, no doubt, passages where Kant speaks of ‘a cause which brings together the required matter, modifies it, forms it and puts it in its appropriate place’; but against these must be set the explicit statement ‘that if the body has an alien principle (the soul) in communion with it, the body must either be the instrument of the soul—which does not make the soul a whit more comprehensible—or be made by the soul, in which case it would not be corporeal at all.’ Vitalism can glean small comfort from this. Let us turn, then, to the second authority.
As we have seen already, the souls or functions of nutrition and perception are, in the Aristotelian biology, ultimately to be expressed as alterations or movements of the particles of the body; mind alone is separable from body and eternal.
In the development of the individual organism the mind comes in from outside, but the two souls of lower order are present in the σπέρμα, or κύημα, as Aristotle calls it, which results from the commingling of the male and female elements, or, as we should say, the fertilized ovum. The material and efficient causes of development are not, however, both contributed by each of the parents.