One version of McTaggart's argument for the unreality of time is:
- If time is real, there is change.
- If there is change, there is fundamental change, and it is the change of events or instants from future, to present, to past.
- There is no fundamental change of events or instants from future, to present, to past.
- So there is no change.
- So time is not real.
We need three principles:
- If something undergoes non-Cambridge change from being F to being non-F, then at some time it exists and is F and at some time it exists and is non-F.
- Cambridge change is never fundamental.
- Everything that exists is present, and neither past nor future, when it exists.
- Nothing exhibits a non-Cambridge change from being future to being present, or from being present to being past, or from being future to being past. (6 and 8)
- Hence nothing fundamentally changes from future, to present, to past. (7 and 9)
I think the contemporary A-theorist should deny (2). And most do.