'Appearing Equal' at Phaedo 74 B 4-C 6: an Epistemic Interpretation

The argument at Phaedo 74 B 4‐C 6 that the equal itself is ‘something different from’ sets of physical equals depends on Leibniz's Law: there is a property that perceptible equals have that the equal itself does not have. What I call the ‘epistemic interpretation’ holds that the property is an epistemic one: having appeared unequal. The ‘ontological interpretation’ holds that the property is not epistemic, but simply the property of being unequal. The most natural reading of the text favours the epistemic interpretation; scholarly support for the ontological interpretation is based on the widely held view that on the epistemic interpretation the argument is manifestly invalid. But this view implicitly relies on an impoverished sense of ‘appearing’ as equivalent to ‘being thought’. Drawing on an analogy with colour perception, I elaborate an experiential sense of ‘appearing’ which makes Plato's argument on the epistemic interpretation philosophically defensible.