Per se unity 2

Here are some more thoughts on 'per se unity'. I had a post on this earlier.

For Aristotle, change occurs when a subject x acquires a form F. There are, however, two broad types of change: substantial change, and accidental change.

In substantial change, the subject is a lump of matter, and the form is a substantial form. The matter and substantial form together constitute a substance (e.g., Socrates' matter and a substantial form constitute the human person Socrates).

In accidental change, on the other hand, the subject is a substance, and the form is an accidental form (e.g., when Socrates goes to the beach and gets a tan, Socrates is the subject, and his tan color is an accidental form).

According to Aristotle, matter and a substantial form have 'substantial unity' (or 'per se unity', as it's also called), and a substance and its accident has 'accidental unity'. And for Aristotle, the constituents in a substantial unity are tied together much more tightly than those in an accidental unity. For instance, the matter and form in Socrates are tied together more tightly than Socrates and his tan color.

But as far as I can see, it's very difficult to identify the precise way that a substantial unity is tighter than an accidental unity. In both cases, the constituents are related to each other in many of the same ways. Consider the following.

(1) In both cases, the subject can survive the gain and loss of the form. For instance, Socrates can lose his tan, but Socrates' matter can likewise lose his human form.

(2) In both cases, the form can only exist by inhering in a subject. An accident like a tan color can only exist when it inheres in a subject (like Socrates), but Aristotle thinks that applies to substantial forms too: Socrates' human form can only exist when it inheres in a lump of matter.

(The Christian scholastics believe human forms can survive the death of their bodies, but that's a special case. We can easily use a different example to make the same point: even the Christian scholastics believe that Beulah the cow's substantial form can only exist in a lump of matter.)

(3) In both cases, the identity of the composite depends on the identity of its constituents. For Aristotle, Socrates would be destroyed if his matter and form were separated, but 'tan-Socrates' also cannot survive if its constituents are separated: 'tan-Socrates' ceases to exist when Socrates loses his tan.

(4) In both cases, the subject and the form are related in terms of potentiality and actuality. For instance, Socrates' matter has the potential to have a human form, and Socrates' human form actualizes that potential. Likewise, Socrates has the potential to be tan, and his tan color actualizes that potential too.

So for both accidental and substantial unities, the form actualizes a potential in the subject, the form can only exist by inhering in the subject, the subject can survive the loss of the form, and the subject and the form together constitute a unity that cannot survive if the subject and the form are taken apart. In what way, then, are substantial unities 'tighter' than accidental unities? I don't know.

It's tempting to say that while Socrates' tan color is tied to Socrates only 'accidentally' (i.e., 'loosely'), a human substantial form is tied to Socrates essentially (i.e., much more 'tightly'). But this does not help, for it equivocates on the meaning of 'Socrates'.

When we say the tan color is accidental to Socrates, we are taking Socrates as the subject of the tan color. But when we say a human substantial form is essential to Socrates, we are taking Socrates as the composite of a subject (matter) and a form.

Thus, although Socrates is the subject of his tan color, Socrates is not the subject of his substantial form. Rather, Socrates' matter is the subject of his substantial form. So while it's true that Socrates' tan color is accidental to its subject (Socrates), it's also true that Socrates' human form is accidental to its subject (Socrates' matter).

Similarly, although Socrates is the composite of which his substantial form is an essential component, Socrates is not the composite of which his tan color is an essential component. Rather, 'tan-Socrates' is the composite of which the tan color is an essential component. So while it's true that Socrates' human form is an essential component of the composite Socrates, it's also true that Socrate's tan color is an essential component of the composite 'tan-Socrates'.

Thus, we need to be careful when we talk about how constituents are 'essential' or 'accidental' to their subjects and/or composites. In both cases, the forms are accidental to their subjects, but essential to their composites.

Per se unity

The scholastics often follow Aristotle in saying that the matter and form in a living organism have 'per se unity'. What's that?

Well, the basic idea is that different ingredients can be tied together more or less loosely. Consider the following cases.

(i) Items in a pile of trash are tied together extremely loosely. It doesn't take a lot of force to separate them, and the items aren't held together in a pile because they each have some intrinsic power to join together.

(ii) Socrates and his pale color are tied together more tightly than a trash pile, but not so tightly that they can't be taken apart, so to speak. After all, Socrates can get a tan, in which case Socrates and his pale color are no longer together. It doesn't necessarily take a lot of force to separate them, for natural processes like getting a tan can do the job; we don't need God stepping in here. Also, Socrates and his pale color do have intrinsic powers to join together. Socrates has the (passive) power to be pale, for example.

(iii) Matter and form are supposed to be tied together far more tightly than either of the previous two scenarios. The way that matter and form come together to form 'one thing' is, for the Aristotelians, a paradigm case of unity. But like case (ii), it doesn't necessarily take a lot of force (like God) to separate matter and form, for natural processes like copulation and decomposition can do the job. And like case (ii), matter and form do have intrinsic powers to join together. Matter, for example, has the (passive) power to acquire a form.

The problem is, it's incredibly difficult to define 'per se unity', at least for the scholastics (it's also difficult for Aristotle, but I'm not interested in that here). There are a number of difficulties here.

I can define accidental unity like this: when a substance x (like Socrates) and an accident F (like his pale color) are tied together, x can survive the gain and loss of F. In other words, F does not determine the identity or persistence conditions of x. So x and F are tied together loosely enough that they can separated without x being destroyed.

One is then tempted to say that per se unity occurs when some x and F are tied together so tightly that they can't survive being taken apart. But that doesn't work. Here are some counter examples.

(a) Living organisms gain and lose matter all the time. Particles are constantly flying out of and into me, and biological cells are continually dying and being regenerated. I see no reason why an organism can't survive a total replacement of its matter. Aristotle, I think, says this somewhere (though I can't remember where, and I may be mis-remembering this fact). The scholastics also think so, but for an additional reason: they believe the body is restored (replaced?) after death, and most believe that God could miraculously replace a sick person's heart with a new, healthy heart, so mutatis mutandis for the whole body.

(b) Matter can survive the loss of a form, and indeed this is what happens in every normal case of change down here on earth. For example, when water is turned into steam, the scholastics (following Aristotle) would say that a chunk of matter first has the form of water, and then it loses that water-form and acquires a steam-form; but the matter is the very same throughout the whole process. As with all Aristotelian changes, the matter (by definition) persists throughout the change.

(c) For the scholastics, the soul can survive the loss of its body. They believe the soul survives for a time without its body, after it dies. Right now I have my body, but when I die, my soul gets separated from my body, and then it gets reacquainted (over coffee, probably) with a body in heaven.

So matter and form aren't inseparable. For all intensive purposes, it looks to me like they're tied together in exactly the same way that a substance and an accident is. Matter can survive the gain and loss of a form, and a form (like the human soul) can survive the gain and loss of matter.