If you are interested in how actual historical methods are routinely used to prove the nonhistoricity of persons and events, a perfectly common result in the field, see my book Proving History on the underlying methodology, and my discussion of examples in On the Historicity of Jesus (e.g. index, "Ned Ludd," "John Frum," "Betty Crocker," "Moses") and how reference classes already establish who is likely to be real or fake (such as based on mythotypes and naming conventions) see Chapters 5 and 6 therein. This is not difficult. The only time it becomes uncertain is when we lack all pertinent data (hence we cannot conclude on the historicity of Lao Tzu, Confucius, Buddha, or even Muhammed).
See also my discussions of the methodological issues in my articles on Hannibal and Muhammed:
Note the issue is never what we can "always" or "never" do. History, like all empirical facts, can only ever be known to one probability or another. So this question is always: "How probable does the evidence make [x]" where [x] can be any fact of history, including the existence of a person. Even if you want to insist the probability of [x] is 50% you still need to present an evidence-based reason for why you think that. You can't just arbitrarily declare probabilities. What I show in JFOS and OHJ is only that Jesus is less likely to have existed than to have been mythically constructed; indeed my formal conclusion is that on the evidence available, the probability of his existence cannot be higher than 1 in 3. But 1 in 3 is actually still a respectable probability of existing.
So don't confuse this as about proving someone did or didn't exist. All that is being proved is the probability that they did.
If you are interested in how actual historical methods are routinely used to prove the nonhistoricity of persons and events, a perfectly common result in the field, see my book Proving History on the underlying methodology, and my discussion of examples in On the Historicity of Jesus (e.g. index, "Ned Ludd," "John Frum," "Betty Crocker," "Moses") and how reference classes already establish who is likely to be real or fake (such as based on mythotypes and naming conventions) see Chapters 5 and 6 therein. This is not difficult. The only time it becomes uncertain is when we lack all pertinent data (hence we cannot conclude on the historicity of Lao Tzu, Confucius, Buddha, or even Muhammed).
See also my discussions of the methodological issues in my articles on Hannibal and Muhammed:
https://www.richardcarrier.info/archives/13785
https://www.richardcarrier.info/archives/8574
Note the issue is never what we can "always" or "never" do. History, like all empirical facts, can only ever be known to one probability or another. So this question is always: "How probable does the evidence make [x]" where [x] can be any fact of history, including the existence of a person. Even if you want to insist the probability of [x] is 50% you still need to present an evidence-based reason for why you think that. You can't just arbitrarily declare probabilities. What I show in JFOS and OHJ is only that Jesus is less likely to have existed than to have been mythically constructed; indeed my formal conclusion is that on the evidence available, the probability of his existence cannot be higher than 1 in 3. But 1 in 3 is actually still a respectable probability of existing.
So don't confuse this as about proving someone did or didn't exist. All that is being proved is the probability that they did.