What a thing to ask: what is truth! If you take it seriously, it's such a radical question, that everyone should be confronted with it from early on, on a regular basis. Truth is what corresponds with facts, right? But proving the earth is round didn't help convince potential sponsors to fund ships exploring the western waters. They were probably still afraid their ships would fall off the edge. So it's what's generally accepted? Sure, and thus you're limiting yourself by the superstition of others. And as for that little voice inside... How can you be sure it's speaking the truth? I can imagine many war criminals claimed they were listening to it, just to come to terms with their horrible actions. Ultimately, it seems like each of us is on their own figuring out the truth for themselves. We can help each other, but the final decision has to be made by us. I guess that's what being human is.