One might raise the question whether statement and opinion are changeable or not; for it seems that the same statement is both true and false. For example, the statement that a man is sitting, were it true, the same statement will be false when he has got up. Similarly with opinions. For if anyone thinks truly that somebody is sitting, when he has got up this same opinion will be false, if he still holds the same opinion about him. Hence these will be changeable, as being, though numerically one and the same, able to receive contraries.
Still, even if anyone were to admit this, yet there is a difference in the mode. For statements and opinions themselves remain completely unchangeable in every way, but as the actual thing has been changed the contrary comes to belong to them. For the statement that somebody is sitting is always the same; it is because the actual thing changes that it comes to be true at one time and false at another. Similarly with opinions. For opinion, though being unchangeable too, when the actual thing is changed is said either true or false. Further, truth or falsity is neither at statements only nor at actual things only, but at the application of statements to actual things. For just as footwear is regarded neither at feet only nor at shoes but at the application of shoes to feet, so truth too is regarded at the application of statements to actual things.
Unconditionally, no statement or opinion is changed at all by anything. So they are not able to receive contraries as substance does so. For substance, since it is able to receive contraries, changes in quality, while none of these is being moved by the other; for statement is not responsible for the alteration of the actual thing and its actuation from contraries to contraries, nor has the actual thing, as being moved, induced anything of the statement – for the same statement remains unchangeable since nothing happens in it. Further, those which are able to receive contraries are affected (since affection is alteration from contraries to contraries), the things affected are also moved – for affection is motion (alteration).
If then the verbal statement does not remain, but at the same time one is spoken and is gone, it is clear that it is not in motion too (for what does not exist how can be moved?), if it is not in motion, it is not affected either, if it is not affected, it is not able to receive contraries either. But if at all, we might say that the same statement is capable of contraries not in number but in kind. The same case holds good of opinion too.
Bibliography: Aristotle Categories, J. Philoponus in Aristotle’s Categegories
Translation – text editing: George Kotsalis