Objection 2: Time in an Unchanging World Still Needs the World
Even in the frozen world scenario, we do not know that time is a substance. The time we are aware of needs other things. When discussing things in time, we often do discuss change—for example, the changing location of apples. Yet, we can also have periods of time in which things do not change, but instead merely persist.4 They only exist from one moment to another, with no change in their properties or relations to other things. For example, the apple may sit on a table, unchanging: not rolling about, not rotting, and persisting in its colour. In that case, the object persists through a period of time without change.
This persistence of things does not show the kind of independent substantial time. Nor does it give a reason for holding that time is more than a property of other things.
However, Shoemaker argues that the presence of an unchanging period of time cannot be explained by anything that is frozen in that period. The period, no matter how long it lasts, does not start because it is prompted by some physical or mental process. Nor does it end—and change begin again—because some physical or mental process prompts it to end. Whatever processes the other things in that world are in when a freeze occurs, those processes continue when the freeze ends.
This also means we cannot explain the freezes merely through the temporal properties and relations of other things. The freezes have their own rules and regularities which are imposed externally on everything else and continue without regard to the non-temporal rules governing those other things.
As such, to explain the start and stop of global freezes, we can only appeal to something about time itself. Whatever it is we appeal to, we are appealing to time independent of other things—and so, we are appealing to time as a substance.
Objection 3: Shoemaker-Style Arguments Do Not Suit Lived Experience
Shoemaker-style arguments do not suit actual lived experience. In some possible world, we might justifiably infer substantial time from the way the world freezes in separate places. Yet, this is not what we do in the actual world. There are no frozen parts of the actual world, or at least we do not know if there are any.
In the actual world, how could we know about time without change? A natural response to this objection is that is not the point of Shoemaker’s argument. The argument is to show that, given the right circumstances, we would be justified in believing that there is time without change. As such, we would be justified in believing substantivalism is true.
Yet, the questions are still there about time as we actually live in it. There may be a possible world in which its inhabitants are justified in believing time is a substance. But this does not justify any beliefs we may have that time is a substance here.
For example, when I talk about the time it takes for an apple to go from ripe to rotten, I do not mean some independent time, such as asserted by Newton. I mean by time a number of changes in the world, for example, the ticks in a clock on my phone, or the changes in months, days, or seasons, or even changes in the colour and shape of the apple.
That is, we talk sometimes as if time is a substance. But Shoemaker’s argument only shows that we could be justified in believing it to be true. It does not justify the belief that it is true.