For a large class of cases - though not for all - in which we employ the word meaning it can be defined thus: the meaning of a word is its use in the language.
- Ludwig Wittgenstein
If you can't have truth which meets all the epistemic and linguistic justification criteria to say 'This is 100% true', then believe the claims and methods to reach and inquire into those claims that currently meet the most of those justification criteria. Just be ready to change your mind a lot and don't lose reasonable standards in scrutinising Existence. Don't make the standards so impossible that you might as well do nothing, since no form of data or thought will meet those standards.