In the absence of a reliable formula Trial-And-Error is the only practical way. Fortunately we don't need to Reinvent-The-Wheel for every little detail in life. There are others we can learn from using observation, reading, study, discipline (or discipleship). All these methods are imperfect. But they may save us from repeating the grossest errors of the past. And then again they may not.
You should get a good notion that something is true or exists, when the evidence comes up and slaps you in the face.
Don't believe anything.
In the bible, when Jesus spoke to Saul, Saul knew. Why didn't he just think he tripped and fell? Had eye problems?
When God reaches us, we know. It's as in-flight went through us. You notice.
It's experiencing, not thinking.
I don’t. I believe even though I assume my position is wrong.
First, one must find evidence. Then, one must show others the evidence.
We only know truth by asking God, not by analyzing. Observations can be analyzed, but they aren't truth.
If it works then its good
And if it ain't broke then don't fix it
Usually if it is verified by several sources, it is true.
Everything is evidence.
But what is the credibility of the evidence?
Generally speaking; one does not.
Truth is one of the central subjects in philosophy. It is also one of the largest. Truth has been a topic of discussion in its own right for thousands of years. Moreover, a huge variety of issues in philosophy relate to truth, either by relying on theses about truth, or implying theses about truth.
It would be impossible to survey all there is to say about truth in any coherent way. The problem of truth is in a way easy to state: what truths are, and what (if anything) makes them true. But this simple statement masks a great deal of controversy. Whether there is a metaphysical problem of truth at all, and if there is, what kind of theory might address it, are all standing issues in the theory of truth.