The teaching of Aristotle is that the matter is provided by the female and the female alone. The egg (or catamenia in mammals) is described as being mere matter (ὕλη), body (σω̑μα), potentiality (δύναμις), passive (παθητικόν) and merely quantitative, although it is true that a sort of soul, the nutritive, is somewhat grudgingly conceded to it, since unfertilized eggs appear in some sense to be alive. The male element, on the other hand, provides the principle of motion (ἀρχὴ τη̑ς κινήσεως) and the form (εἰδος); it is qualitative, it is activity, it produces the perceptive soul, if it is not itself that soul, and it is responsible for the ‘correct proportionality’ (λόγος) of the organization. The male element contributes only motion, but no matter; it acts upon the female element as rennet acts when it coagulates milk, except that the analogy is incomplete, since the γονή brings about a qualitative and not merely a quantitative change in the material on which it operates. To this it imparts the same kind of motion which itself possesses, the motion which was present in the particles of the food in its final form from which it was itself derived. The communication of this motion is enough to set going the machinery (αὐτόματον); the rest then follows of itself in proper order.
Lastly, the sperm of the male acts like a cunning workman who makes a work of art, using heat and cold as the workman uses his tools: for this heat and this cold could never of themselves—by coagulations and condensations—produce the form of the body as the older naturalists had supposed, regarding only the efficient and ignoring the formal and the final cause: for the organic body is not what it is because it is produced in such and such a fashion, rather it is because it is to be such and such that it must be developed as it is.
And here lies the kernel of the whole matter. For while Aristotle has made it perfectly plain that, according to his idea, the soul, at least its nutritive and perceptive faculties, is to be regarded as a function of matter and that this function may be ultimately expressed in terms of movement, and further that development is a mechanism which is set going by the communication of motion proceeding from the ‘soul’ of the male element and derivable eventually from the motions into which the ‘functions’ or ‘soul’ of the parent can be resolved to the mere matter which the female provides, it is equally evident that he does not regard this mechanical explanation—in terms of material and efficient causes—as satisfactory or complete. But when we inquire why, he gives us no certain nor consistent answer. On the one hand, there are passages in which he tells us that there must be something which controls the material forces and imposes on them a limit and proportionality of growth; that the soul makes use of them as the artist makes use of his implements, and such passages are naturally interpreted by Driesch in the sense of a ‘dynamic’ teleology; it is the ψυχή which superintends and controls, and the ψυχή is ‘entelechy’.
Elsewhere, however, we are informed that even the proportionality of the developing parts is simply the outcome of the motion imparted by the male, which is actu what the female element only is potentia.
Moreover, it may be questioned whether Aristotle ever intended to imply more than an ‘analogy with the causality of purpose’ when he uses the figure of the workman and his implements to illustrate his meaning of the formal cause. The formal cause of a work of art is an intelligible vera causa; it is the idea in the mind of the artist antecedent to the execution of the work; but the formal or final cause of an organism, the end which it apparently strives to attain, can only be said by a metaphor to be prior in time to the existence of the organism itself. Prior in thought, however, it certainly is, for it is only the performance of its functions (ἐντελέχεια) by the organism complete in all its parts that makes the mere mechanism of development comprehensible to us; the process, therefore, exists for the sake of the end. Only as efficient cause is the soul prior in time; only so far as it is prior in thought can it be said to be a final cause.
Such a teleology is, it is obvious, indistinguishable in principle from the position in which Kant leaves us. It is the position adopted by Driesch himself in his earlier Analytische Theorie, but abandoned in the Vitalismus in favour of a theory of ‘psychoids’.
Now quite apart from the meaning which Aristotle may or may not have intended to convey, there are grave objections to this belief. This ‘psychoid’, to which the name ‘entelechy’ is surely misapplied, this rudimentary feeling and willing, which is aware of the form it desires to produce, must be psychically at least as complex as the phenomena it is designed to account for, and stands, therefore, as much in need of explanation as they; as Kant has observed, this will involve us at once in an infinite series of such entities. In fact it is only a photograph of the problem, and not a solution at all.
Again, when we ask what the modus operandi of this cause is, we get no reply either from Driesch or from any other neovitalist. The objection that the intervention of a psychical cause in a physical process is unintelligible, an objection which would probably appeal to many, may be waived, for in the last resort the connexion between any—even simple mechanical—causes and effects is equally hard to understand.
It may, however, be doubted whether these entities are not being multiplied beyond necessity, and whether the progress of science would not be better served by an adherence to a simpler philosophy. But even when it has discarded the psychoid we find vitalism still denying the possibility of mechanical explanation, still preaching the autonomy of the organism. The ‘dynamic’ teleology of Driesch has only disappeared to be replaced by the metaphysical doctrine of the final cause.