One simple question

[Purple Rabbit]

IMO, this question is just a restatement of the "what is absolutely true?" question, and the problem with that one is that you can only have a chance in answering it when you've defined the term "absolulety". As long as you can't, you're just aimlessly groping around in the dark. But this shortcoming is not to be regarded as personal failure since even the most succesful human endeavour in trying to solve this, the scientific method, can't answer this one.

Ultimately there is no absolute proof to refute solipsism (there is a practical argument however)
Ultimately there is no absolute proof to refute the brain in a jar idea
Ultimately there is no absolute proof to refute the idea of The Matrix

Be my guest to present these absolute proofs if you have one.

So, with the lack of an absolute proof of ultimate reality, we are left with the second best option and that is to understand the world as we know it assuming it presents itself in some consistent pattern to us. Some call this option science, others might call it vanity.