John Pollock (1940?2009) was an influential American philosopher who made important contributions to various fields, including epistemology and cognitive science. In the last 25 years of his life, he also contributed to the computational study of defeasible reasoning and practical cognition in artificial intelligence. He developed one of the first formal systems for argumentation-based inference and he put many issues on the research agenda that are still relevant for the argumentation community today. This paper presents an appreciation of Pollock's work (...) on defeasible reasoning and its relevance for the computational study of argument. In our opinion, Pollock deserves to be remembered as one of the founding fathers of the field of computational argument, while, moreover, his work contains important lessons for current research in this field, reminding us of the richness of its object of study. (shrink)

Conciliatory views of disagreement say, roughly, that it’s rational for you to become less confident in your take on an issue in case you find out that an epistemic peer’s take on it is the opposite. Their intuitive appeal notwithstanding, there are well-known worries about the behavior of conciliatory views in scenarios involving higher-order disagreements, which include disagreements over these views themselves and disagreements over the peer status of alleged epistemic peers. This paper does two things. First, it explains how (...) the core idea behind conciliatory views can be expressed in a defeasible logic framework. The result is a formal model that’s particularly useful for thinking about the behavior of conciliatory views in cases involving higher-order disagreements. And second, the paper uses this model to resolve three paradoxes associated with disagreements over epistemic peerhood. (shrink)

1. In May 2013 I had an email exchange with Philippe Besnard, continued in September that year, on his paper with Amgoud and Besnard (2013) and its relevance for the ASPIC+ framework (Modgil & Prak...