My observations. In Zeta 16 Aristotle argues that (a) a substance must be one (1040b5-16) and (b) yet one cannot be the substance of a thing (1040b16-27). Here I have four sets of questions/observations:
(1) the association of potentiality and matter (1040b5-8),
(2) the problem of the unity of natural kinds/elemental stuff (1040b8-10),
(3) the relation of unity and being (1040b16-27), and
(4) Aristotle's criticism on the one over many (1040b27-1041a3).
(1) In 1040b5-8 Aristotle mentions that a number of things that are commonly thought to be substances are actually potentialities: "Evidently even of the things that are thought to be substances, most are only potencies, both the parts of animals (for none of them exists separately; and when they are separated, then too they exist, all of them, merely as matter)..."
Issue: How can we better understand the potentiality? Aristotle appears to associate potentiality with matter here. Bostock hence suggests what Aristotle means by potentiality is just "matter." Recall that in Z15 (1039b27-30) matter is said to be "capable both of being and not being."
My question: Bostock seems to me broadly correct. But we also need further qualification. Can we justifiably say that the potential two halves of a line is the matter of that one line (Zeta 13, reason (4), 1039a3-14)? Shouldn't the matter of that one line be one line instead of two halves?
(2) In 1040b8-10 the natural kinds/elemental stuff such as earth, water, air and fire are denied the titled "substance" because "none of them is a unity, but as it were a heap, until they are concocted and some unity is formed from them."
Issue: How and by what are those natural kinds/elemental stuff concocted and formed a unity? Bostock offers an example: the earth might be concocted into a more developed material, say wood, from which a genuine unity, such as a tree, was formed. It seems that the natural kinds need a form, e.g. tree, to make it a unity.
My question: Would Aristotle allow the haecceity make the natural kind/elemental stuff a unity? For instance, this wood!
(3) In 1040b16-19 Aristotle mentions that neither unity nor being can be the substance of things, since "unity is predicated in the same way as being," "the substance of what is one/unity is one/unity," and "things whose substance is one/unity is one/unity."
My question: What does Aristotle mean by "unity is predicated in the same way as being" (1040b16)? I don't understand.
Observation: Bostock suggests that "the substance of what is one/unity is one/unity," and "things whose substance is one/unity is one/unity" should be understood as "things whose substance is numerically one are themselves numerically one." I wholly agree.
(4) In 1040b27-1041a3 Aristotle proceeds to a diagnosis of the basic error of "those who believe in the forms." Notice that the word used is eidos rather than idea. Bostock suggests, the "forms" in question may be taken to include the things that Aristotle calls forms as well as things that Plato calls forms.
Issue: On the one hand, Aristotle says, the Platonists were right to suppose that if forms are to be substances then they must be separate; on the other, it was a mistake to suppose that "the one over many" is a form.
My question: In what sense can Aristotle's criticism on the one over many be counted as a conclusion from the previous discussion on the relation of substance and one? (Recall our two main theses in Z16: a substance must be one (1040b5-16) but one cannot be the sustance of a thing (1040b16-27)).
If we follow the previous argumentation in Z16, then the one over many cannot be sustance, since "one" is common to many. A substance belongs to nothing but to itself and to that which has it (1040b23-24). But what Aristotle says here is that it is wrong to count this universal, one, as a form rather then as a substance.
So it seems that either (a) Aristotle's criticism on the one over many cannot be counted as a conclusion from the previous discussion on the relation of substance and one, or (b) Aristotle switches his meaning of form here, namely he associates/identifies (Aristotelian) form with substance, and holds that the one over many cannot be "Aristotelian form." I’m in favor of (b).
