LEWIS’S ARGUMENT FOR TEMPORAL PARTS

1. It is (logically) possible that an object-stage (a thing having all the short-term properties of a particular sort of physical object, but existing only for a brief period) might exist.

2. It is (logically) possible that two such stages might exist in succession, without overlap, and with the initial qualities of the second matching the final qualities of the first.

3. It is (logically) possible that there might be a world consisting of such stages that is exactly like our world in its distribution of intrinsic local qualities through space and time.

4. It is (logically) possible that such a world be exactly like our own in its local causal relations (since these are constrained only by the distribution of local qualities).

5. Such a world would be entirely like our own in every respect (since all features of the world supervene on the distribution of local qualities and causal relations).

6. Our own world is a world of such stages, which therefore exist.

7. Since ordinary objects exist too and do not exist apart from these stages, they must be have these stages as parts.