OK. Let’s go over the key steps to Aristotle’s demonstration. The key to a good demonstration is to begin with what is easiest to know, and then to proceed, by argument, to what is harder to know.
The first and easiest thing for us to know is that
something exists outside of us. This “something” is what Aristotle calls
to on (in our languages
ens or
el ente). This
ens is not some mysterious, underlying
arché, but simply the things, the beings (
ta onta), that we encounter every day.
(2) These
ta onta are not all equal. Even though we attribute (
categorein)
to on to all sorts of things—trees, clods of dirt, and the ocean; but also to colors, sizes, weights, and actions—it is evident that we don’t attribute them in exactly the same way.
(3) There is a priority of one of these figures of attribution, which we call
substance (
ousia). (Note that I am not denying that Aristotle came up with that particular usage of the term
substance**; but he hardly pulled the concept out of thin air.) The others (the
symbebékota, or accidents) all refer in some way to substance.
All of these are observations made directly from experience and the analysis of language.
[Up to here, we are using material from *Metaphyiscs Book IV; now on to Book VII].
(4) The characteristics of the first figure of attribution, substance, are that it is definite (it is a
tode ti—i.e., it can be indicated with the definite pronoun
tode, “this”) and independent (
choristón, “separate” from other realities, not completely dependent on something else). Again, this is simply a recognition from experience: I can indicate
this tree, and see that it stands by itself; its greenness and brownness, on the other hand, do not have an independent existence.
(5) The very notion of substance indicates its priority over accident: as you point out, Aristotle chose the term
ousia to indicate those realities that have definite and independent existence. Hence, there is not much to prove here—it is in the very notion. However, the notion is well founded, not simply made up.
(6) Substance is prior to accident in knowledge. This is not exactly the same thing as (5) it has to do, not with the notion of substance itself, but our knowledge of substances. Rather, he says that we know something most truly when we know “what” it is, not simply “what its properties are.” He does not go over his theory of abstraction (which is how we learn “what” something is) here—for that, we would need to go to his
De anima. There, he argues that in our intellectual process, we first get a notion of the whole, and only afterwards fill in the details about its properties. Knowledge of accidents always presupposes knowledge of the substance they depend on.
(7) Substance is prior to accident “in time.” In order for there to be any accidents, there must first be a substance on which these accidents depend. In his words, “For none of the other categories [technically, the “categoremata,” the realities indicated by the categories] can exist separately, but substance alone (1028a34).”
The demonstration is not terribly long, because substance is such a basic notion, but it is there.
So, it seems that the harder thing to know in this case would be that “ousia” is prior to accidents both ontologically and in the order of what we know. I eliminated the explanatory comments in your post above and interpreted what you said in some bullets using what you said in the others. The resulting sentences were as follows:
*]I know that things exist outside of me.
*]Some of those things existing outside of me are not completely dependent on others.
*]I call “substance” the things existing outside of me that are not completely dependent on others.
*]Some other things completely depend on others.
*]I call “properties” those things that depend on others.
*]Things that are not completely dependent on others are definite.
*]To know something most truly is to know what it is.
*]To know something less truly is to know its properties.
*]The things I know first are those that are not completely dependent on others.
*]To know the things that completely depend on others presupposes the knowledge of those things that are not completely dependent on others.
*]If a thing A depends on a thing B, I say that B has ontological priority over thing A.
As you can see, this is not an argument, but a set of loose sentences; and some of them even seem to belong to disjoint sets; so, I eliminated the ones that do not belong to the same set and those that seem redundant. This is what was left:
*]I know that things exist outside of me.
*]Some of those things existing outside of me are not completely dependent on others.
*]Some other things completely depend on others.
*]The things I know first are those that are not completely dependent on others.
*]If a thing A depends on a thing B, I say that B has ontological priority over thing A.
Naturally, the elimination of some of the sentences does not make the remaining ones to constitute an argument, but they did not make it before.