The person who posted this was asking why mathematicians believe in Pythagoras, or why philosophers believe in Socrates, given that there’s little to no hard evidence that either was ever actually a living breathing person. The source of this question is rooted in the fact that there are a growing number of scholars calling into question the idea that Jesus ever existed. And we’re not even talking about the idea that Jesus was just an ordinary human historical figure who has been exaggerated to mythical proportions. These scholars (collectively referred to as “mythicists”), make the claim that there may never even have been that much; that the entire Jesus narrative was a myth that does not refer to any real person whatsoever.
I’ve heard some of the arguments in favor of the mythicist position, and while they do seem to have some merit I can’t say that I am necessarily convinced by them. I just don’t feel like I have enough information to make a judgment yet. I also don’t know any of the evidence for or against the existence of Pythagoras or Socrates. But that’s not really necessary for addressing the question at hand: why accept the existence of Pythagoras or Socrates on little or no evidence, but not accept the existence of Jesus?
It has to do with the nature of the claims, and what depends on them.
You see, belief in Pythagoras is trivial. He was a Greek mathematician, perfectly ordinary in every way except for a gifted intellect, who supposedly founded a school of math and philosophy in Ancient Greece, and is credited for a number of advancements in the mathematical field (most famously: the Pythagorean Theorem that is named for him). I know Greeks exist; I’ve met some. I know mathematicians exist; I’ve met some of those as well. I know schools exist that teach mathematics; I’ve been to a couple. It’s reasonable to believe Greek mathematicians exist, and some of them have founded schools. Nothing about believing in Pythagoras asks us to accept anything preposterous.
And what is credited to Pythagoras? Mainly, a lot of mathematics, none of which actually depends in any way on Pythagoras having been a real person. Whether Pythagoras existed or not, the square of the hypotenuse of a right triangle would still be equal to the sum of the squares of the other two sides. That’s mathematically provable and physically demonstrable, and the possibility that we may have accredited that statement to a fictional person makes not one bit of practical difference.
In other words, it’s the fact that the existence of Pythagoras is utterly unimportant that makes it easy to accept without specific evidence. You don’t need to prove the existence of Pythagoras, precisely because whether he really existed or not makes absolutely no difference. And it’s reasonable to accept the existence of Pythagoras because doing so doesn’t require you to discard your everyday observations about the world. If you find out you were wrong, it’d make almost no difference in how you viewed the world or lived your life.
Contrast that with the claims for Jesus. Many Christians will tell you that the most important statement attributed to Jesus is “I am the Way, the Truth, and the Life; nobody comes to the Father except through me.” This is a statement that requires a complete revision of one’s understanding of the world and how one ought to be living one’s life. That statement is utterly, completely, irrevocably dependent on Jesus actually existing, and actually being the person who made that claim. That is the barest minimum that must be true in order for that statement to have any possibility of being true. If Jesus never actually existed, that statement cannot possibly be anything more than a metaphor, and the stories of his life cannot be anything more than parables.
Of course, the existence of a historical Jesus-figure is far from sufficient to justify believing any of the fantastical claims made about him. There easily could have been an ordinary man preaching in ancient Israel who couldn’t walk on water, who couldn’t conjure food out of nothing, who wasn’t the son of God, but around whom a body of fantastical legendry grew. It wouldn’t be hard to believe that guy existed. But it also wouldn’t matter much – just as whether Pythagoras existed or not doesn’t matter much. It’s the divine claims that make it imperative to know if Jesus existed, and demand that evidence of his actual existence be pursued that much more rigorously. So it’s reasonable to dig into the question. And if, in the course of trying to prove whether the divine figure existed, you can’t even find the evidence to prove whether the ordinary historical figure existed, what reason would you have to believe it anymore? The intellectually honest thing for someone in that position would be to admit that they don’t have reason to believe Jesus existed.
So yeah, in the strictest sense, there may be no more reason to believe in Pythagoras or Socrates than in Jesus. But it’s reasonable to prioritize the relative importance of granting or withholding belief – or even whether it bears investigation - based on the nature of what depends on the claim. Belief (or nonbelief) in any of them ought only to be provisional anyway, open to change with the emergence of new evidence.