I've been beating up on Analytical Egalitarianism quite a bit lately (see here, here, and here). Now Sandra Peart, a leading proponent of this view, has risen to the challenge.
According to Peart, scholars should assume equal human abilities because otherwise they might give in to temptation to shade the truth:
Without AE, we wonder whether truth-seeking is incentive compatible...
Consider models with agents of different fixed types. Suppose a modeler proposes to pick who is in the “better” and who in the “worse” class. If the modeler can do this and policies follow from the exercise, the modeler may benefit. That’s one incentive issue. We consider rewards from both material sources and applause.
[O]nce we allow for difference to creep into the analysis, the incentives are asymmetric: the theorist gains more by showing difference than similarity.
As far as I can tell, Peart's argument boils down to: If researchers are allowed to claim they (or their group, or their sponsors, etc.) are somehow better than average, they have an incentive to do so. This leads them to err on the side of inegalitarianism.
So far, so good. But we have a standard toolkit for dealing with researcher bias: asking to see the evidence, double-checking the work, asking probing questions, looking around for contrary evidence, and so on. What makes the "vanity of the philosopher" such a special problem? Inquiring minds want to know.
Admittedly, the standard toolkit is not perfect. But imposing the plainly false assumption of Analytical Egalitarianism in the name of methodological hygiene is far worse. We could just as well argue for Analytical Hermaphrodism: "If we admit that there are two genders, researchers will argue that their gender is somehow better than average. Therefore, in the name of incentive compatibility, researchers should assume that there is only one gender." In both cases, we would be dogmatically embracing a massive falsehood to guard against a moderate potential bias.
Even if you reject this analogy, Peart seems to neglect the possibility that some people might be biased in an egalitarian direction. I find this extremely odd, because in the modern intellectual world, this is the standard bias! Look at all the "applause" Murray and Herrnstein got. The primary effect of Analytical Egalitarianism is not, therefore, to counteract our tendency to think we're better than other people. It is to make it even more costly to challenge popular egalitarian platitudes.