Traditionally, this puzzle has been solved in various ways. Aristotle, for example, distinguished between “accidental” and “essential” changes. Accidental changes are ones that don't result in a change in an objects' identity after the change, such as when a house is painted, or one's hair turns gray, etc. Aristotle thought of these as changes in the accidental properties of a thing. Essential changes, by contrast, are those which don't preserve the identity of the object when it changes, such as when (...) a house burns to the ground and becomes ashes, or when someone dies. Armed with these distinctions, Aristotle would then say that, in the case of accidental changes, (1) and (2) are both false—a changing thing can really change one of its “accidental properties” and yet literally remain one and the same thing before and after the change. (shrink)

An introduction to the theories of endurantism and perdurantism, and persistence more broadly.

In Re realism is the two-pronged view that, first, when this and that have the same color, this color and that color are identical. There is just one color, the universal. Second, on the view, this color exists just in case something has it. Say my cat has the same color as the dog I owned when I was a child. Since the dog existed before the cat, and precedence being irreflexive, it seems plausible to infer that the dog and (...) the cat are distinct. Now take the colors. Since the colors are allegedly in re, and thus perhaps somehow elements of the cat and dog, it seems plausible to infer that the dog's color also preceded the cat's color. And therefore that the cat's color cannot be identical with the dog's. Finally, since the in re realist understands the sameness of properties in terms of identity, it follows that the cat's color cannot be the same as the dog's. The problem generalizes: What is the relationship between universals and time? Ignoring the temporality of that which constitutes time, to be temporal is to have a temporal "feature." These "features" are of three kinds: precedence, times, and being present, past, etc. The fundamental question in each case is whether universals have the feature. Do universals precede? Are they at times? Are they present? Time, I argue, is essentially the field in which things happen. To happen, I argue, is for one thing to do something. For one thing to do something is for the thing to exemplify a property. Such exemplifications of properties by objects I call "states of affairs." Only states of affairs precede, are at times, or are present. Universals, not being states of affairs, are not temporal. But, by the same argument which shows that running is not temporal it can be shown that Jack is not, even though Jack's running obviously is. So far I have defined what it is to be temporal; primitive temporality. But since Jack is a constituent of something temporal, he may be justly thought of as derivatively temporal. (shrink)