How people distinguish well-justified from poorly justified arguments is not well known. To study the involvement of intuitive and analytic cognitive processes, we contrasted participants’ personal beliefs with argument strength that was determined in relation to established criteria of sound argumentation. In line with previous findings indicating that people have a myside bias, participants (N = 249) made more errors on conflict than on no-conflict trials. On conflict trials, errors and correct responses were practically equal in terms of response times (...) and mouse-tracking indices of hesitation. Similarly to recent findings on formal reasoning, these findings indicate that correct reasoning about informal arguments may not necessitate corrective analytic processing. We compared findings across four argument schemes but found few differences. The findings are discussed in light of intuitive logic theories and the notion that evaluating informal arguments could be based on implicit knowledge of argument criteria. (shrink)