“The core of Aristotle’s teleological theory of natural generation lies thus in the fact that whatever comes to be already possesses that form in potentiality, and that its source already possesses that form in actuality. Empedocles is criticized by Aristotle exactly because he failed to see these facts (PA.I.1, 640a22-26): “He failed to see, first, that the seed previously constituted must already possess this sort of potentiality, and, next, that the producer was prior not only in definition but in time; for it is the man that generates a man, and therefore it is because that man is such, that this man’s coming to be happens so.” There is thus no backwards pull by final causes from the future: it is the form that is present from the outset, received from another natural being in which that form has already been realized, that determines the outcome of the process of generation which is its actualization and final cause; it is the fully actualized form of the father that is used as a starting point of the explanation of the development of the offspring.”
“Explanation and Teleology in Aristotle’s Philosophy of Nature,” Ph.D. Diss., University of Leiden (2007), by Mariska Leunissen, pp. 24-25.
The validity of the point hangs on whether the Form which contains the later developments potentially is seen as thereby an efficient cause of the later developments. One might be tempted to this view by our modern reading of what is going on, in which the Form is identified with the genetic code, say, which, through definite efficient causal processes, produces the adult outcome. But that is probably misleading. The Substantial Form is not associated with a structure which, due to the simple efficient causal laws followed by its components, will progressively develop into the adult. There is no explanation why that potentiality is there, and none is expected. It just is in the Form. So the Form aims at that outcome, and this potentiality is present because it does. If the Form acts, it acts with the outcome “in mind.” The commonsense view associated with the reduction of final to efficient cause is not here at all. The realization of potential is perhaps sometimes due to efficient causal activity, but the notion of potentiality is (1) metaphysically realist, and (2) much broader than the notion of a potentiality present due to a structure and its efficient causal activity. Aristotle no more wants to reduce mental intention and the like to mechanism than does Plato. It is fundamental, and has, and requires, no explanation. Minds do it, and Aristotle says, Forms do it. But not Separated Forms, rather particular substantial Forms. If there is no pull from the future, just a push from the past, found in the push of a potentiality striving to realize itself, what a potentiality is and how it pushes is not explained at all. The functionalist account, perhaps, but without the real causal level producing something like the function level, without the “as if” sense of the thing. The adding machine adds. Either that, or it doesn’t, and just imitates addition, and then it is not an adding machine, but an imitation of one. Only minds add, then, and they are not machines. Note the drift from “potentialities” as real existing things we can refer to, found “in” things, which seems OK, to potentialities as objects without parts, or as being in such objects, namely in Forms, so that they cannot be explained, other than saying “this is the Form of a Cat, you know, not a Squirrel.” I was once told, more or less condescendingly, by an older scholar that the composition in Aquinas’s thought of Form and Matter is a metaphysical composition, not a material one. He was right, of course, but does this mean anything more than this, that Thomas refused to give any account of this sort of composition, relying entirely on the metaphorical connection to material composition to reassure us that we know what he is saying? Of course, he does give an account, but we are asked to imagine that the particular matter and the particular Form do not exist separately from one another at first, and then get joined, for that is impossible, since they must be joined if either is to exist. Except, of course, that the Form does not really have to, since it can exist without matter if it is the right sort of Form, a human soul, say. In fact, the Form is the reality, and matter is just an aspect of some Forms. The world consists in Substances, which, it turns out, are rather like minds. Indeed, the whole drift of the Aristotelian view of causality is in fact towards Idealism.
To go back to the beginning, what about the point that the fully realized Form in the parent is the cause of the fully realized Form later appearing in the child? Well, we have to get from here to there, and that is not simply a matter of a fully realized Form, a particular object, all along. Rather, the fully realized Form produces seed, which is not fully realized, and after that it has done its job and the seed, in the environment of the womb, does the rest. (The father’s child can be posthumous, but it can’t occur once the developing embryo has died.) Why does the seed develop into a rabbit? Because it is rabbit seed, that is, because it has in the unrealized potentiality of a rabbit, not the unrealized potentiality of a banana tree. Some account what this potentiality is, and how it develops into a rabbit, is needed, something beyond the information-free truism that potential rabbits tend to develop into rabbits if things go right. The talk about potentiality does not just cover up talk about complete actuality leading to another complete actuality. It has to be taken seriously.