Both are logical fallacies, and they get in the way of progress in science in general, and in evolutionary psychology in particular. However, as [Matt] Ridley astutely points out, political conservatives are more likely to commit the naturalistic fallacy (“Nature designed men to be competitive and women to be nurturing, so women ought to stay home to take care of the children and leave politics to men”), while political liberals are equally likely to commit the moralistic fallacy (“The Western liberal democratic principles hold that men and women ought to be treated equally under the law, and therefore men and women are biologically identical and any study that demonstrates otherwise is a priori false”).Really? This is true? Assuming it is (and wit that I am free from having to actually look it up ;), that's pathetic. I count myself as a liberal in America (in Denmark I would not, as the political spectrum is different), but the moralistic fallacy is so absurd that I swear I would never commit it in a thousand years*. It's not that I would commit the naturalistic fallacy either, but I'd like to argue that it isn't quite as batshit insane in its logic as the moralistic fallacy. I mean, what is real could be imagined to have a bearing on how we view life, the universe, and everything, but how we view that could never ever in any way affect what is real.
The big difference in committing these two logical fallacies is that the naturalistic fallacy (in this context equal to the is/ought fallacy [see a discussion of that in Massimo Pigliucci's blog, Rationally Speaking]) at least makes it explicit that the (wrong) step from what is to what ought to be is made. The moralistic fallacy, as much as I have identified it in arguments, is never made explicit, and is therefore much more (... dangerous is a strong word, so thank the saurus) pestilential (I love it!). The view of how things ought to be is sort of kept secret (because as people aspiring to be rational, we all know that this should have no bearing on an argument about what is), and will of course be vociferously denied in case it is identified by any of those pesky republicans (or well-meaning but naive liberal scientists):
Since academics, and social scientists in particular, are overwhelmingly left-wing liberals, the moralistic fallacy has been a much greater problem in academic discussions of evolutionary psychology than the naturalistic fallacy. Most academics are above committing the naturalistic fallacy, but they are not above committing the moralistic fallacy. The social scientists’ stubborn refusal to accept sex and race differences in behavior, temperament, and cognitive abilities, and their tendency to be blind to the empirical reality of stereotypes, reflect their moralistic fallacy driven by their liberal political convictions.Here I am, then, going to have to disagree with Kanazawa. It is indeed possible to commit the moralistic fallacy without talking about ought, because political or ideological conviction need not be clarified for people to express what their conformation bias makes them conclude.
It is actually very easy to avoid both fallacies – both leaps of logic – by simply never talking about what ought to be at all and only talking about what is. It is not possible to make either the naturalistic or the moralistic fallacy if scientists never talk about ought. Scientists – real scientists – do not draw moral conclusions and implications from the empirical observations they make, and they are not guided in their observations by moral and political principles. Real scientists only care about what is, and do not at all care about what ought to be. [Emphasis added.]
* Full disclosure: Last year I was accused of committing the naturalistic fallacy by two people who continues to commit the moralistic fallacy**. Isn't that ironic?
** Fuller disclosure: I am aware that that's my interpretation of written words, but do judge for yourself, and let me here what you have to say.