Consensus among historians about the existence of Jesus - authority fallacy?

You make a perfectly valid argument. I would clarify it by simply saying that consensus historians lean toward the probability of Jesus’s historicity, whereas mythicists lean toward his mythological origins. 

Over the last 2,000 years most of the speculations about Jesus were written, forged, interpolated, and revised by men and women who believed Jesus Christ was their divine savior. So, it’s not exactly bereft of confirmation bias. More dangerously, for a lengthy part of that time you could be tortured and executed for suggesting otherwise. That tends to be somewhat persuasive as an argument.

Thankfully, in the information age the consensus is rapidly changing to a more balanced view, and some historians are giving it an extremely generous range between 6% -30% chance of probability.

After exhaustive research on the subject I favor the mythicist consensus. Either way, Dr. Robert Price sums it up most succinctly:

 ‘Even if there was a historical Jesus lying back of the gospel Christ, he can never be recovered. If there ever was a historical Jesus, there isn’t one any more. All attempts to recover him turn out to be just modern remythologizings of Jesus. Every “historical Jesus” is a Christ of faith, of somebody's faith. So the “historical Jesus” of modern scholarship is no less a fiction.’

You have to prove forgery, not prove that something isn't a forgery.  You have to prove that Jesus was forged, not the reverse that he was not forged.  The appeal to authority in this case is a 'defensive' one, which I think is actually a valid exception.  'I don't believe you can actually prove your case because if you were right the actual authorities would not have a consensus against you', as opposed to 'X authorities agree that Jesus is forged therefore he is'. 

Yes, you are right, any consensus is not proof in itself. However, the evidence in various sciences (even in history) is often very complex, and can be vague to those who do not have sufficient knowledge of terminology and other facts that have already been accepted. That is why, often, instead of presenting evidence, they simply invoke scientific consensus.
Although this is not 100% logically justified, limited by our own mental capacities (memory, reasoning ...) we turn to sticking to only "reliable" sources.
Like science, we are sometimes forced to use induction and analogy, which unfortunately deviates from the ideal logical deduction.

Jesus existed because there's a consensus among historians that he did exist.

Yes, this is a clear appeal to authority . However, if we soften the claim to

There's a consensus among historians, both religious and secular, that the Jesus figure probably did exist, so it is reasonable to accept that he probably did exist.

Then no fallacy. In the latter example, we are simply accepting a claim probabilistically based on a consensus of experts (historians) rather than claiming a fact to be true or false.

Because we have secular historians mostly agreeing that Jesus did exist (I think this is the case but not sure) then we can rule out the consensus being formed based on faith or wishful thinking (if Jesus didn't really exist, Christianity falls apart). Without that secular consensus, we would need to be far more skeptical.

This is a great question. I have argued elsewhere that there is no such thing as consensus in science and that arguments strongly asserting the so-called "scientific consensus" on a particular issue often amount to the appeal to authority you have cited. (Interesting side note: In the Latin version of this fallacy, the word verecundiam has the sense of shame, as in shaming people into submission by citing experts!)

I hadn't thought about this with regard to history or other "softer" disciplines. Consensus may not be scientific, but is it historical? If it's true that "history is written by the victors," shouldn't we also be suspicious of consensus in this area? I think so. 

With regard to Jesus, Christian apologists are fond of pointing out that there is more historical evidence for the existence of Jesus than for the existence of Julius Caesar. I'm not sure if that is true, but it strikes me as an interesting way to interrogate the "consensus among historians" idea. On the one hand, we have to be careful about favoring expert beliefs over evidence. On the other hand, we also have to be careful about moving the goalposts in the sense of demanding more evidence than is usually required to prove an historic figure existed.

In any case, I would formulate an argument in favor of the existence of Jesus like so:

• There are detailed, firsthand accounts of the existence of Jesus in the New Testament.


• There are also several accounts of the existence of Jesus outside of the New Testament (e.g. in the writings of the first-century Jewish historian Josephus) that corroborate those accounts.


• Therefore, Jesus existed.

No, because the historians cite to outside proof for the proposition Jesus was real.  It is only a fallacy of consensus if it is just opinion.