In what way is Socrates a primary substance?

Question

In Aristotles logic (organon) he says:

If I say that Socrates is a man, I have said what Socrates is, and signified a substance (ousia)

There is some ambiguity here: Is he saying that Socrates is a substance, or the genus man is?

He distinguishes between primary and secondary substances; and it appears that, for example, the genus man is a secondary substance; this would suggest that Socrates is a primary substance; but he writes:

A substance, that which is called a substance most strictly, primarily, and most of all - is that which is neither said of a subject, nor in a subject. I've the individual man or individual horse.

How can Socrates be a primary substance, but at the same time it can't be in him, nor said of him?

Answer 1

See Aristotle's Categories :

Aristotle divides what he calls ta legomena (τἃ λεγόμενα), i.e. things that are said, into ten distinct kinds. Things that are said according to Aristotle, are words, and so it is natural to interpret his second system as a classification of words. [...] There are three reasons to think that Aristotle is not primarily interested in words but rather in the objects in the world to which words correspond.

For me, this is a key point in reading Arstotle : the interplay between logico-linguistic analysis and metaphysics.

that are neither said-of nor present-in anything. Such entities, Aristotle says, are primary substances. Although he only gives a negative characterization of primary substances in the Categories — they are neither said-of nor present-in — the examples of them that he provides allow us to form a more robust conception of what a primary substance is supposed to be. His favorite examples are an individual man and a horse. So, it is natural to interpret him as thinking that among primary substances are concrete particulars that are members of natural kinds.

It seems that, saying that substance "is that which is neither said of a subject, nor in a subject" must be interpreted from the logico-linguistic point of view : a particular cannot be "predicate of" some other particular (it cannot be said od a[nother] subject) nor can be "attributed to" something.