A temporal part would be something like "the first year of a person's life", or "all of a table from between 10:00 a.m. on June 21, 1994 to 11:00 p.m. on July 23, 1996".
[1][2] This claim is still commonplace, but philosophers like Ted Sider believe that even endurantists should accept temporal parts.
Not everyone was happy with the definition by analogy: some philosophers, such as Peter van Inwagen, argued that—even given the definition by analogy—they still had no real idea what a temporal part was meant to be,[3]: 131 whilst others have felt that whether temporal parts existed or not is merely a verbal dispute (Eli Hirsch holds this view).
Later perdurantists identified persisting objects with events, and as events having temporal parts was not problematic (for example, the first and second halves of a football match), it was imagined that persisting objects could have temporal parts.
There was a reluctance from many to identify objects with events, and this definition has long since fallen out of fashion.
For example, if a person changes from having long hair to short hair, then the temporal-parts theorist can say that change is the difference between the temporal parts of a temporally extended object (the person).
However, those who reject the notion that ordinary objects, like people, have temporal parts usually adopt a more common-sense view.
An argument widely held to favor the concept of temporal parts arises from these points:[8] David Lewis' argument from temporary intrinsics, which he first advanced in On the Plurality of Worlds.
This is so because temporal parts exist only at an instant, and therefore it makes no sense to speak of them as having properties at a time.