Finding objective truth simply means starting from logical law as a premise, and as long as someone accepts that logic even exists and isnt too stupid, they must accept premise 1 because premise 1 is merely a basic logical law.
Good example of premise 1 is:
P1. A is true or Not A is true
there is no way to disagree with this premise, without denying that logic even exists.
So as long as someone accepts that logical laws exist, any first premise made in form of logical law itself must be accepted as true.
Another example of objective truth is definitional conditional premise:
P1. If definition of A is B, then A is B
this premise remains true by law of identity.
third, weaker form of objective truth is observational premise.
P1. We see that A happens with B
But this one can be denied by questioning validity of observations
But objective truth isnt gained by debating, or polls, or "experts". these entirely depend on who decides what truth is. A perfectly reasonable argument can be rejected, while unreasonable one may be accepted, depending on who the "judge of truth is".
the main problem in determining truth is that such right cannot be exclusive to anyone. In same way reciprocity works with morality, it likewise works with truth determining. If you say "We decide what truth is", I can simply say "No, I do.".