Abstract

Cognitive studies seem to show that two kinds of tasks are controversial. Both have a quantified premise, a quantified conclusion, and a disjunction in the premise. The difference is that the quantifier (both in the premise and in the conclusion) is existential in one of them, and universal in the other one. In both cases, the conclusion is one of the disjuncts. To infer its disjuncts from a disjunction is not correct in First-Order Predicate Calculus. However, people tend to accept the conclusion when the quantifier is existential and reject it when the quantifier is universal. I try to argue that a non-axiomatic logic with truth-values with two numbers can come to those results too.