More (or Moore?) on Compresence of Opposites

A natural view to take about Plato is to say that he holds (in the 'middle' dialogues at least) that anything perceptible is either changing or open to change--it is therefore 'becoming', a condition intermediate between nothingness and being--and that therefore at least in some respects, and perhaps in all, it somehow has opposite properties at the same time--because change is not unnaturally viewed as a thing's simultaneously sharing in the terminus a quo and terminus ad quem of the change. (If the changing thing didn't simultaneously share in these, it would be either one or the other and wouldn't be changing.)

If I had to describe the doctrine of Compresence of Opposites in Plato, that's how I'd describe it initially.

But the version of the doctrine one finds in Irwin is something else entirely, so much so that I'd hesitate to describe is as a doctrine of Compresence of Opposites at all.

Irwin's thought is similar to G.E. Moore's "Open Question Test" in the Principia Ethica. Suppose we define 'beauty' in terms of some shape or color. But it will remain an open question whether something with that shape is beautiful -- in fact we won't find it hard to imagine a case where something with that shape is beautiful, and another case in which something with that shape is ugly. The property of having that shape, then, is compatible with both beauty and ugliness. Thus both opposites, beauty and ugliness, are 'present' in that shape--that is to say, some tokens of that type of shape are beautiful, and some are ugly.

According to Irwin, that's what Compresence of Opposites amounts to for Plato.

Now I won't judge whether this view is philosophically more sophisticated than the simple, or even simplistic, view which I sketched at the beginning of this post.

But I do think it's wrongheaded as an interpretation of Plato for various reasons, of which I'll mention two.

First, the interpretation is 'against the intention of Plato' (as it sometimes used to be said), because the wrong things get included as examples of 'Compresence of Opposites'. For example, on Irwin's interpretation, that a circular shape can be either green or not green, or a green surface either circular or not circular, would illustrate Compresence of Opposites -- but that kind of thing is surely not what Plato meant in the passages that lead us to ascribe such a doctrine to him.

Second, Plato frequently discusses cases in which one and the same thing has opposite appearances at the same time (large and small, equal and unequal, one or indefinite, cp. Rep. 478d2, εἴ τι φανείη οἷον ἅμα ὄν τε καὶ μὴ ὄν), and, far from taking these to be strange cases insofar as they involve relatives (which is what Irwin says to dismiss them), he apparently takes them to stand for what is true but less evidently so of anything perceptible.

To my mind, Irwin's view seems plausible only on the supposition that Plato postulated Forms in order to deal with difficulties of definition--his view seems to be a translation, really, into an ancient context of relatively recent disputes about whether mental and ethical terms can be defined with observables--whereas 'Compresence of Opposites' in Rep. V and especially in the Phaedo is presented more as a way of dealing with phenomena of causation (sc. dependence) and change.