I recently read a post by
The Incredible Hulk The Uncredible Hallq where he points out the problem with the absence of “low-hanging fruit” in philosophy and Historical Jesus research. That post had a link to a post on the blog of awesome, “Less Wrong”: Some Heuristics for Evaluating the Soundness of the Academic Mainstream in Unfamiliar Fields. Here are some of the heuristics that the poster feels can tell you if you’re dealing with a field that has run out of research space, so to say, and is now kinda just making stuff up to “sound cool” (or worse).
Low-hanging fruit heuristic
As the first heuristic, we should ask if there is a lot of low-hanging fruit available in the given area, in the sense of research goals that are both interesting and doable. If yes, this means that there are clear paths to quality work open for reasonably smart people with an adequate level of knowledge and resources, which makes it unnecessary to invent clever-looking nonsense instead. In this situation, smart and capable people can just state a sound and honest plan of work on their grant applications and proceed with it.
In contrast, if a research area has reached a dead end and further progress is impossible except perhaps if some extraordinary path-breaking genius shows the way, or in an area that has never even had a viable and sound approach to begin with, it’s unrealistic to expect that members of the academic establishment will openly admit this situation and decide it’s time for a career change. What will likely happen instead is that they’ll continue producing output that will have all the superficial trappings of science and sound scholarship, but will in fact be increasingly pointless and detached from reality.
Is this a problem for Historical Jesus research? How many books about the “real” historical Jesus are there out there? The evidence for him hasn't changed since the books of the NT were written… what else can be said? It seems as though all of the low-hanging fruit has been taken.
Ideological/venal interest heuristic
Bad as they might be, the problems that occur when clear research directions are lacking pale in comparison with what happens when things under discussion are ideologically charged or a matter in which powerful interest groups have a stake. As Hobbes remarked, people agree about theorems of geometry not because their proofs are solid, but because “men care not in that subject what be truth, as a thing that crosses no man’s ambition, profit, or lust.” 
One example is the cluster of research areas encompassing intelligence research, sociobiology, and behavioral genetics, which touches on a lot of highly ideologically charged questions. These pass the low-hanging fruit heuristic easily: the existing literature is full of proposals for interesting studies waiting to be done. Yet, because of their striking ideological implications, these areas are full of work clearly aimed at advancing the authors’ non-scientific agenda, and even after a lot of reading one is left in confusion over whom to believe, if anyone. It doesn’t even matter whose side one supports in these controversies: whichever side is right (if any one is), it’s simply impossible that there isn’t a whole lot of nonsense published in prestigious academic venues and under august academic titles.
Is this a problem for Historical Jesus research? Especially Christian scholarship's reaction to the idea that Jesus didn't exist? This is a thought I touched on in a previous post. How could a committed Christian investigate the actual historicity of their religious leader without any bias? Are they a Christian first and a scholar second? How could they allow themselves to produce any scholarship that would be damaging to the Christian cultural hegemony? The only safe way to ensure this heuristic is passed is by looking at Historical Jesus research done by non-believers. Ones who have an emotionally disinterested scholarly interest in the Historical Jesus. I for one don't care whether Jesus existed or not. I'm not sure I can say the same for any committed Christian.
Finally, what are the evident exceptions to these trends?
I can think of some exceptions to the low-hanging fruit heuristic. One is in historical linguistics, whose standard well-substantiated methods have had great success in identifying the structure of the world’s language family trees, but give no answer at all to the fascinating question of how far back into the past the nodes of these trees reach (except of course when we have written evidence). Nobody has any good idea how to make progress there, and the questions are tantalizing. Now, there are all sorts of plausible-looking but fundamentally unsound methods that purport to answer these questions, and papers using them occasionally get published in prestigious non-linguistic journals, but the actual historical linguists firmly dismiss them as unsound, even though they have no answers of their own to offer instead.
Is this a quality that Historical Jesus research has? One where its “standard well-substantiated methods have had great success[es]”? I'm not sure how you can qualify or quantify “success” in historical Jesus research. As far as I know, as historical Jesus research progresses it has produced a Jesus with a million faces. In other words, we get less certain about the historical Jesus and not more as time goes on.
These heuristics, to me, explain the visceral reaction that proponents of an ahistorical Jesus face from the cultural hegemony. I kinda think there was a historical Jesus, but not for any really academically sound reason.