In this essay, I consider an evolutionary debunking argument (EDA) that purports to undermine the epistemic justification of the belief in the reliability of our belief-forming processes, and an evolutionary vindicating argument (EVA) that seeks to establish that such a belief is epistemically justified. Whereas the EDA in question seems to fall prey to crippling self-defeat, the EVA under consideration seems to fall prey to vicious circularity. My interest in those arguments and the problems they face lies in what they (...) might tell us about the possibly aporetic nature of reason. For, if we take the EDA and the EVA in question to consist of true or plausible premises and valid inferences at which we arrive through a meticulous use of reason, then their falling victim to either crippling self-defeat or vicious circularity might be regarded as a sign that, when we push rational reflection on the reliability, or lack thereof, of our belief-forming capacities to the limit, we end up in a situation of aporia from which there seems to be no escape. (shrink)

In this paper I develop an account of petitio principii (the fallacy sometimes also called ‘vicious circularity’, or ‘begging the question’) which has two crucial features: it employs the notion of doxastic justification, and it takes circularity to be relative to an evidential state. According to my account, an argument will be circular relative to an evidential state if and only if having doxastic justification for the conclusion is necessary, for a subject in that evidential state, to have doxastic justification (...) for the premisses. I compare the account to some existing ones, and claim some advantages. I then rebut an objection which threatens to undermine the importance of one of those advantages. This account seems to shed new light on the old problem of characterizing petitio principii. It avoids the two obvious problems which any account of this phenomenon must face: being too narrow, for example by leaving out all arguments in which the conclusion does not appear among the premisses, and being too wide, making all valid arguments circular. (shrink)

In light of recent developments in argumentation theory, we begin by considering the account that Aristotle gives of what he calls sophistical refutations and of the usefulness of being able to recognise various species of them. His diagnosis of one of his examples of the grouping that he labels epomenon is then compared with a very recent account of the matter, which, like Aristotle, calls on us to attribute a mistake or confusion to anyone who uses this kind of argument. (...) From examination of three other examples that Aristotle himself supplies of epomenon, it appears that there are cases of inferences of this kind that we need not, and perhaps cannot, avoid making. The suggestion is made that this is because the whole family of what Peirce calls abductions have important characteristics in common with epomenon. (shrink)

1. La logica è la teoria del ragionamento corretto. O come si dice di solito, è una teoria normativa del ragionamento. Non intende fornire una descrizione del modo in cui di fatto si ragiona, ma cerca piuttosto di chiarire in che modo si dovrebbe ragionare. Questo però non significa che la logica possa prescindere dall’osservazione dei ragionamenti che di fatto sono ritenuti corretti. Qualsiasi teoria che pretenda di fissare norme per un certo ambito deve tenere conto dei giudizi preteorici i...