Summary

There is no (logical) reason to believe in the past.

Mathematician-philosopher Bertrand Russell:

There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that ‘remembered’ a wholly unreal past.

Forget “five minutes ago”; there’s no way to prove that it didn’t all just spring into being now, with all the apparent evidence for a past (including the objects and people around you, your memories, pictures from “yesterday”, etc.) having been manufactured on the spot.

The first thing that will happen is you will think “well sure there’s no way to prove it, but that’s obviously very unlikely.”

How can well tell if it’s likely or unlikely? Let’s try various things.

The laws of physics suggest it’s extraordinarily unlikely.

The laws that were proven in the past and that you learned in the past? That’s circular reasoning.

Occam’s Razor suggests that the simplest solution is best, and a real past is simpler.

Try justifying Occam’s Razor without reference to the past. You only trust Occam’s Razor because it has worked before. Circular.

But I’ve been reading this document for at least 30 seconds.

No you haven’t; it all popped into being… now.

Mathematically speaking, there are many more possibilities in which time is real, so overall it is more likely that time is real.
A theory’s predictive power is a good test of its truth. A real past gives more predictive power, so that’s evidence of its correctness.
…

Again, try to justify these assertions. You will either find yourself starting with axioms that presuppose time, or else making logical steps that assume it in some way or another.

Long story short: there is no justification that is not circular. Thus there is no justification at all. How can you say that something is “very likely” when you have no logical justification for it?

It is not “rational” to believe in time. You might argue that it’s rational because believing leads to better outcomes than not believing, but that’s just saying that it’s practical. It is not grounded in reason, though it certainly feels that way.

It may be comfortable or convenient to believe in the past, but that has nothing to do with it being likely or rational.