Form, Substance

Faced with questions like what the world is “made of”, modern people have generally assumed that it must be some kind of “stuff”. The usual presumed answer is some sort of matter-stuff, or less commonly some sort of mind-stuff.

Plato and Aristotle already suggested a radical alternative to this way of thinking that takes the accent away from “stuff” altogether. Aristotle especially developed a rich account of how we think about these kinds of things, by looking at how we express these kinds of questions, and what we are implicitly trying to get at when we ask them.

The most obvious simple answer attributed to Plato and Aristotle is form. In Aristotle’s case, one should also mention what has been traditionally called substance.

Etymologically, eidos — the Greek word we translate as “form” — seems to begin from a notion of visual appearance, with an emphasis on shape. It acquired a more abstract sense related to geometrical figure. Plato attributed great significance to the practice of geometry as an especially clear and perspicuous kind of reasoning, but he also recognized a broader kind of reasoning associated with a dialectic of question and answer, which comes into play especially where questions of value are concerned. From a point of view of ethical practice and human life generally, questions about what something really is and why this rather than that are more important than what things are made of (see What and Why). Already with Plato, “form” came to be inseparable from meaning.

Aristotle’s classic discussion of substance (ousia) in the Metaphysics starts from the idea of a substrate in which properties inhere. This most superficial level later inspired the Greek grammarians to articulate the notion of a grammatical subject of predicates. In what I think is the single greatest example of ancient dialectic, Aristotle gradually steps back from the simple notion of a substrate. Substance becomes “what it was finally to have been” a thing, at the end of the day so to speak. But then this is further interrogated to disclose the level of actuality, or what is effectively operative in a process. But it turns out that actuality is not complete in itself. What is effectively operative does not form a self-contained whole that explains everything. A fuller understanding must take into account potentiality, which leads to a transition away from simple actuality to a larger perspective of processes and degrees of actualization, in which nothing is simply given just as it is. Aristotle was especially concerned with the forms of living things, which have this character.

The more interesting senses of form for Plato and Aristotle do not refer to something that could be simply given. In line with this but in a more speculative mode, Plotinus suggested that every form somehow in a way “contains” all other forms. The poetic truth in this is that the articulation of one form depends on the articulation of other forms, and while everything in some sense coheres, we have no unconditional starting point. We always begin in the middle somewhere, in a context that has yet to be fully elaborated. The work of elaboration is itself the answer. (See also Interpretation.)

The Importance of Potentiality

I think modern philosophy generally is handicapped in its thinking about the empirical world by its lack of a notion like Aristotelian potentiality. To build context, I need to first say a bit more about the role of actuality.

The modern concept of a factual, existing world is relatively close to Aristotelian actuality, but the first big difference is that it is not paired with anything. The modern concept of a factual world is something that is supposed to be complete in itself, whereas for Aristotle, actuality in the world is always complemented by some correlative potentiality. Aristotle did not consider actuality alone to be sufficient to account for the world as we experience it.

Actuality also does not exactly correspond to a state of things, but rather expresses what is effectively operative. This is semantically a bit deeper than a notion of state. At the same time, it does not have state’s strong implications of complete determination. It also does not have the monolithic unity of a state. Actuality in the world consists of many coexisting things. Further, it is not intended by itself to provide all the resources needed to account for change and what happens next. This is related to the fact that for Aristotle, the operative determination of things is not entirely univocal. (See also Equivocal Determination.)

Enter potentiality. Potentiality is exactly what is not univocal in the actual determination of things. It corresponds to multiple alternative concrete possibilities of realization already implicit in current reality. This is a far more specific notion than mere logical possibility. Potentiality is closely tied to and informed by the current actuality, in that it exactly occupies the real gaps or holes in the actuality’s incompletely univocal determination. For each aspect of things where there is not univocal determination, there are instead multiple potential alternatives. This correlates with the fact that, for Aristotle — in contrast to Poincaré’s classic formulation of modern determinism — the present does not completely determine the future.

Poincaré famously claimed that from the state of the universe at any arbitrary point in time, its entire future is completely determined. This resembles the Stoic notion of fate, transferred to a modern event-based model of causality. For both the Stoics and Poincaré, the world is completely univocally determined. Like Aristotle, they emphasized the intelligibility of the world and of change in the world, but they made the very strong assumption of complete univocal determination. Aristotle did not.

Aristotle’s notion of intelligibility was broadly semantic, whereas Poincaré’s was mathematical. With semantic interpretation, there is always a question of how far we develop the account, which in principle could be extended indefinitely. It thus naturally lends itself to an account of incomplete determination, corresponding to some stopping point. Aristotle does not claim any more determination than he can show. Poincaré’s approach, by contrast, requires that we assume there is a complete univocal determination of the world by mathematical laws, even though we can never even come close to knowing enough to show it. This assumption leaves no room for anything like potentiality. Potentiality, it seems to me, could only have a place in a semantic approach to intelligibility.

The modern factual world is usually considered as something that just is, without modal qualification, but I have increasingly begun to doubt whether for Aristotle there is any non-modal account of the world. I read actuality and potentiality both as modal concepts, and everything in the Aristotelian world as parsable into actuality and potentiality.

What’s important about this is that potentiality is not just some mysterious “metaphysical” concept that we could maybe do without. It is a distinct logical/semantic modality supporting multiple virtual alternatives for the same thing. It allows us to intelligibly account for the incomplete determination we really experience, rather than treating real-world incompleteness and ambiguity as if it were a kind of flaw. (See also Structural Causality, Choice; Values, Causality; Structure, Potentiality.)