by Scientia Salon
This paper, which appeared in the journal Synthese in 2006, touches on a sacred cow of internet discourse, especially within atheist and skeptical communities: the idea of informal logical fallacies. I have a paper on the same topic currently in press, together with my co-authors Maarten Boudry and Fabio Paglieri, so we will return to the issue once our paper will be out (Maarten is writing a precis for Scientia Salon, and you’ll see that we advocate an even more radical approach to informal fallacies than the present authors). Meanwhile, below is a taste of what Ulrike Hahn and Mike Oaksford wrote. You can find the full paper here (free).
We examine in detail three classic reasoning fallacies, that is, sup- posedly “incorrect” forms of argument. These are the so-called argumentam ad ignorantiam, the circular argument or petitio principii, and the slippery slope argu- ment. In each case, the argument type is shown to match structurally arguments which are widely accepted. This suggests that it is not the form of the argu- ments as such that is problematic but rather something about the content of those examples with which they are typically justified. This leads to a Bayesian reanalysis of these classic argument forms and a reformulation of the conditions under which they do or do not constitute legitimate forms of argumentation.