Cognitive processes in propositional reasoning

Propositional reasoning is the ability to draw conclusions on the basis of sentence connectives such as "and," "if," "or," and "not." A psychological theory of propositional reasoning explains the mental operations that underlie this ability. The ANDS (A Natural Deduction System) model, described in this article, is one such theory that makes explicit assumptions about memory and control in deduction. ANDS uses natural deduction rules that manipulate propositions in a hierarchically structured working memory and that apply in either a forward or a backward direction (from the premises of an argument to its conclusion or from the conclusion to the premises). The rules also allow suppositions to be introduced during the deduction process. A computer simulation incorporating these ideas yields proofs that are similar to those of untrained Ss, as assessed by their decisions and explanations concerning the validity of arguments. The model also provides an account of memory for proofs in text and can be extended to a theory of causal connectives. (65 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).