Analogical Reasoning and Semantic Rules of Inference

The nature of Aristotle’s topics has been a crucial issue in the Middle Ages (Abaelardi Dialectica, 254) and in the modern and contemporary studies on natural inferences (De Pater 1965; Stump 1982; 1988; Kienpointnter 1986). One of the crucial debates concerned their function, i.e. whether they were instruments for fi nding arguments or rules on which dialectical and rhetorical inferences were based (Bird 1962). The interpretation of the Aristotelian topics as rules of inference, defended by Abelard and Ockham (Bird 1962; Stump 1989), is of fundamental importance for the analysis of natural inferences and argumentation studies in general, as it would lead to a more complex formalization based on the semantic relations between the terms of a consequence (Bird 1960). Inferences such as “This pen is red; therefore it is colored” cannot be considered as purely logical, in the sense of purely formalized according to the semantic system used in modern formal logic. Inferences of this kind hold in virtue of semantic relations between the terms in the antecedent and the consequent, called habitudo in the ancient dialectical theory (Abaelardi Dialectica, 263-264). The habitudo is the semantic-ontological respect under which the terms are connected to each other, and on which the force of the inference depends (Abaelardi Dialectica 254; Rigotti & Greco Morasso 2010: 494). In the example above, the passage from the quality “to be red” attributed to the subject to the different quality “to be colored” is grounded on a relation of semantic inclusion between these two predicates, i.e. a genus-species relation (Bird 1962: 309). This relationship guarantees the inference based on a rule (the maxim) that expresses a necessary consequence of the concept of genus itself. The genus expresses the generic fundamental features of a concept, answering to the question “what is it?”, and is attributed to all the concepts different in kind (Topics 102a 31-32). For this reason, it is predicated of what the species is predicated of. This rule