This from the always lucid Massimo Pigliucci is worth a read.   A key paragraph:

Denialists have even begun to appropriate the technical language of informal logic: when told that a majority of climate scientists agree that the planet is warming up, they are all too happy to yell “argument from authority!” When they are told that they should distrust statements coming from the oil industry and from “think tanks” in their pockets they retort “genetic fallacy!” And so on. Never mind that informal fallacies are such only against certain background information, and that it is eminently sensible and rational to trust certain authorities (at the least provisionally), as well as to be suspicious of large organizations with deep pockets and an obvious degree of self-interest.

Seen a lot of that around here.

via Leiter.