Communicative agency and ad hominem arguments in social epistemology : a commentary on Pierre Jacob

Abstract

A central point in Jacob’s paper focuses on the incompatibility of Grice and Millikan’s account of communicative agency. First, the Gricean mindreading thesis is incompatible with Millikan’s direct perception account. Second, the account of cooperative devices, defended by Millikan, contradicts the Gricean separability thesis in a broad sense. While I agree with Jacob that these positions are indeed incompatible, I will shift focus and concentrate on issues concerning social epistemology with regard to communicative agency. A main issue in social epistemology concerns the accessibility of the speaker’s reliability. How could the hearer remain epistemically vigilant without using fallacious reasoning? (i) I argue that the hearer, in order to be epistemically vigilant, could commit a local ad hominem attack, a process of inductive Bayesian reasoning which is an epistemic tool for assessing the speaker’s reliability. (ii) Compared to this, a global ad hominem attack is a fallacious kind of reasoning, because it undermines knowledge transmission and it cannot be calculated in Bayes’ Theorem. (iii) The account of a local ad hominem attack fits with Grice’s mindreading thesis, which is incompatible with Millikan’s account of direct perception. (iv) The Gricean separability thesis could better explain occurrences of ad hominem attacks than Millikan’s assumption that speaker and hearer are cooperative devices.