In this article we explore an argumentative pattern that provides a normative justification for expected utility functions grounded on empirical evidence, showing how it worked in three different episodes of their development. The argument claims that we should prudentially maximize our expected utility since this is the criterion effectively applied by those who are considered wisest in making risky choices (be it gamblers or businessmen). Yet, to justify the adoption of this rule, it should be proven that this is empirically (...) true: i.e. that a given function allows us to predict the choices of that particular class of agents. We show how expected utility functions were introduced and contested in accordance with this pattern in the 18th century and how it recurred in the 1950s when Allais made his case against the neo-Bernoullians. (shrink)

Contrary to most current epistemologists who concentrate on core cases of rather ‘spontaneous’ trust and belief in the face of assertions, Classical rhetoricians addressed the study of ‘testimony’ as an two-acts phenomenon: that of the ‘disclosure’ of information and that of the ‘appeal’ to its authority in subsequent discursive practices. Moreover, they primarily focused on this second phase as they assumed that it was such argumentative setting that finally gave ‘testimonial’ relevance to the first act. According to this ‘rhetorical’ model, (...) then, it is the dynamics and pragmatics of such complex process that is the core issue regarding ‘testimony’. (shrink)

Imagine the following situation: an act of violent assault has been committed. And there are only two possible suspects, of which one is a small and weak man and the other a big and strong man. The weak man will plead that he is not strong enough and therefore not likely to have committed the crime, which seems reasonable straight away. But there will also be a loophole for the strong man, as Aristotle tells us, who reports exactly that story (...) in book 2, chapter 24, of his Rhetoric. And he also has a name to assign to the inventor of that kind of argument (1402a17–20):The Art of Corax is composed of this topic. For if a man is not likely to be guilty of what he is accused of, for instance if, being weak, he is .. (shrink)

In this paper it is shown how plausible reasoning of the kind illustrated in the ancient Greek example of the weak and strong man can be analyzed and evaluated using a procedure in which the pro evidence is weighed against the con evidence using formal, computational argumentation tools. It is shown by means of this famous example how plausible reasoning is based on an audience’s recognition of situations of a type they are familiar with as normal and comprehensible in their (...) shared common knowledge. The paper extends previous work on this example by using three new multiagent argumentation schemes closely related to the scheme for argument from negative consequences. (shrink)

Contrary to current individualistic epistemology, Classical rhetoric provides us with a pragmatical and particularly dynamic conception of ‘testimony’ as a source made available for the orator by the particular community in which she acts. In order to count as usable testimony, a testimony to which one could appeal in further communications, any discourse must comply with specific rules of social sanction. A deliberate attention to the social practices in which testimony is given and assessed may offer us a more accurate (...) view of its epistemological role. (shrink)