In what follows, I will not challenge premises 4 or 6. Since 3 and 5 are interim
conclusions that follow validly from their predecessors, the remaining targets are
premises 1 and 2. Shields (1999: 261–6) holds that Aristotle is committed to premises
1 and 2. My view is that both premises are false, provided that we understand that
what it is for two beings to be non-synonymously beings is for them to have different
modes of being.
Let’s start with premise 1. To show Aristotle’s commitment to premise 1, Shields
cites the following passage fromPhysicsVII.4, 248b6–11 (Aristotle 1984a: 415):
Non-synonymous things are all incommensurable. Why is [it not possible to say] of what is not
commensurable, e.g. a pen, the wine, or the highest note, whether one is sharper [than the
others]? The reason is that homonymous things are not commensurable. The highest note in a
scale is, however, commensurable with the lead note, since“sharp”signifies the same for both.
Shields also notes putatively other relevant passages:Categories11a5–13 (Aristotle
1984a: 17),TopicsIII.1, 116a1–8 (Aristotle 1984a: 193), and most clearly relevantly,
PoliticsI.13, 1259b36–8 (Aristotle 1984b: 1999), in which Aristotle asserts that a
difference of more or less never is a difference in kind.
It certainly seems then that Aristotle accepts premise 1. But should he have? First,
let’s consider the example Shields explicitly cites. A pen, a wine, and a musical note
can be said to be“sharp”in some sense. Let’s grant that there is a generic sense of
“sharp”so that it even makes sense to talk of them each as being sharp, albeit with
their own respective modes of sharpness. If there is no generic sense of“sharp,”we
cannot make the relevant comparative judgments without augmenting our language
in some way. The question then would become whether there is a possible generic
sense of“sharp”that would permit some kind of comparative judgment.
But is the relation between their respective sharpnesses really like the relation
between modes of being, or other interesting cases of analogy in the philosophical
sense? (In other words, is the analogy apt?) Not obviously. Perhapsbeing sharpis a
mere disjunction. It’s true that two of the disjuncts seem to have the following
commonality: things that are sharp in one of these ways can be unpleasant when
creatures with our constitution are presented with them via the appropriate sensory
modality. Sharp pens hurt to touch; I assume sharp wines are painful to drink. Maybe
the kinds of painful experiences we have in both cases feel similar to each other, and
this is why wefind it appropriate to call both of them“sharp.”Perhaps there can be
also sharp odors emitted by dyspeptic birds. (The“sharpness”of a note is an entirely
different phenomenon, and I will set that sense of“sharp”aside in what follows.) But
this kind of unity is both extrinsic—it depends on the constitution of our sensory
organs—and contingent, since our sensory organs could have been differently con-
stituted. If there is any intrinsic and necessary unity to these modes of being sharp, it
merely consists in the respective categorical bases for the dispositions to cause
unpleasant sensations of a particular sort in creatures constituted in the manner we
actually are. That feels pretty thin to me. Perhaps, though, it is enough to permit a