Prevarication: Reasoning from false assumptions

This paper examines the strategies t~sed in solving prevaricative reasoning problems. The task consisted of a noncontradictory set of propositions followed by an assumption that introduced an inconsistency. Ss were required to restore consistency by assigning truth values to propositions. When reasoning from false assumptions, Ss exhibit a specific strategy in assigning truth values: If forced to choose between the truth of a generality (e.g., All As are Bs) and that of a particular fact (e.g., This Y is a Z), the Ss assign the generality TRUE and the fact FALSE. Affirmative generalities are assigned TRUE more often than are negative ones, and those expressing class inclusion are assigned TRUE more often than those expressing property assignment. The data show that the selection of a "path" through this hypothetical reasoning problem cannot be attributed to either the syntactic form or the preexperimental credibility of the propositions. A generality coding model was discussed in terms of strategies sho~ in prevaricative reasoning problems as well as in other inference tasks.