ABSTRACT
A cognitive account of propositional reasoning must consider both the representation of the propositions (premises and states of affairs) and the context in which the propositions are used. This paper is concerned with reasoning processes involving three different connectives (conjunctive, conditional and disjunctive connectives) in three different tasks (accomplishing a request for action expressed by a premise, judging a state of affairs as true or false with respect to a premise, drawing an inference from two premises). Our claim is that the ability to reason with connectives is explained in terms of construction and manipulation of mental models. We present a computer model that takes as input the modelistic representations of the premises and the specific state of affairs, compares such models and gives rise to a series of model manipulations in order to produce a result, i.e. an action, a judgement or an inference. A computer program reproduces the performances of subjects of different age groups, predicting both correct and erroneous inferences.
