Let’s here take up three of the shobbohat that were raised against Tusi in the previous post. You’ll remember Tusi’s argument, which I stated in two slightly different ways like this:

(a) Every finite existent is either a substance or an accident
The soul is not an accident
Therefore, the soul is a substance

(b) Every existent, except the Necessary Being, is either a substance or an  accident
The soul is not an accident
Therefore, the soul is a substance

Here then are the objections and some responses:

obj 1. Someone may take issue with formulation (a), saying it contains a hidden premise i.e., ‘the soul is finite’. So, unless this premise can be proven, the conclusion will not follow.

resp 1. First, it should be known that the sense of finite in this context concerns existence, so to show that the soul is finite is to show that it has finite existence. That the soul is finite in existence can be proven by this argument.

What is caused has finite existence
The soul is caused
Therefore, the soul has finite existence

Proof of the major: this is because the essence of anything that is caused is distinct from its existence. Proof of the minor: by soul here is meant individual soul. Hence, this premise is empirical in nature i.e., it amounts to the claim that individual human beings (who have souls) are caused, i.e., come into existence at some point in time. That such individuals come into existence is evident empirically. Now if individual come into existence, then so do their souls. And the conclusion follows.

But someone may object to the minor, saying:

obj 1.1. That the individual person may come into existence i.e., is caused, is granted. But it does not necessarily follow that their soul therefore also comes into existence. For given the distinction between soul and body, there is still the possibility that the soul pre-exists – eternally even – the body with whose union an individual person comes into existence at some time. So a proof is needed to rule out this possibility.

resp 1.1. The full argument that the soul does not pre-exist the body is long and complicated. I may treat it later. But what suffices for now is the argument in its syllogistic form, which is:

If the soul pre-exists the body, then it would have to be either (a) numerically single or (b) numerically multiple.
But both alternatives are impossible.
Therefore, the soul cannot have a pre-embodied existence.

obj 2. Someone may say formulation (b) too contains a hidden premise i.e., ‘the soul is not the Necessary Being’. As with (a), the conclusion will not be established unless this is proven.

One response to this is what has been established above. That is, given that the soul is finite, is it therefore not the Necessary Being, who is infinite.

obj 3. Someone may deny the minor by objecting that the soul is the form of the body. As such, it is not a substance but a constituent (i.e., formal) part of a complete substance i.e., the soul-body composite that is an individual man. Now a part of a substance is not itself a substance.

The word substance, Aristotle says Book V of his Metaphysics, has at least four meanings. One of these is ‘that on account of which what is not predicated of a subject is what it is’. In other words, it is what causes what is not predicated of a subject to be what it is. Now what sorts of things are not predicated of subjects? Evidently, such things as individual men, trees, horses, flowers, etc. And what is the cause of the what-it-is-ness of such things? What makes each thing the kind of thing that it is? It is the form of those things. The form of a horse makes the horse a horse and not the matter of the horse. Now the form of a man i.e., what makes him a man and not an animal, is said to be his soul. The reason for this is because he has ‘animality’ in common with the horse. Therefore, according to at least one of the meanings of substance the form of a man i.e., his soul, can be considered a substance.

Further, there seems to be an equivocation on the word ‘part’ in the objection. If by ‘part’ is meant physical part, then it’s true that a physical part of some substance is not itself a substance. For example, the amputated arm of Zayd is not by itself a substance. But, as should be clear from the above, the form of a man is not physically constitutive of him as man.