Page "Identity and change" Paragraph 31

Leibniz's Law can be saved, by saying: Properties are to be described as occurring at particular times, i. e. they are indexed to times.

A property that is described as at a particular time is said to be " temporally-indexed ".

For example, we can say that S1 has mast # 1 in 600 BC.

If we say what time the ship has the mast, then we have indexed the property of having the mast to that time.

We say the ship has the mast then, using the word, " has ", tenselessly.

That means we do not say that it, at present, has the mast, but rather, we say it " has " the mast in 600 BC.

We are not claiming that the ship has the mast at any other time ; just at that time.

But if it were a later time, say 550 BC, that very same ship could " have " mast # 1 in 600 BC, considering that we are talking about a tenseless " have ".

That is, it always has the same properties, but the properties are of the form P-at-T.

This gives us a way to save Leibniz's Law from the objection we gave, but at the same time, brings up the issue of whether change really occurs.

After all, we defined " change " as something having one property at one time, and not at some later time.

By this solution though, any given object always has all the properties throughout time, and the properties are merely temporally-specific.