The Psychology of Uncertainty and Three-Valued Truth Tables.

Psychological research on people's understanding of natural language connectives has traditionally used truth table tasks, in which participants evaluate the truth or falsity of a compound sentence given the truth or falsity of its components in the framework of propositional logic. One perplexing result concerned the indicative conditional which was often evaluated as true when and are true, false when is true and is false but irrelevant" (devoid of value) when is false (whatever the value of ). This was called the "psychological defective table of the conditional.

The class inclusion question: a case study in applying pragmatics to the experimental study of cognition.

For more than 70 years, Piaget's class-inclusion task (given, e.g., five asters and three tulips, the child is asked whether "there are more asters or more flowers") has been the object of experimental investigation.

Preadolescents Solve Natural Syllogisms Proficiently.

"Natural syllogisms" are arguments formally identifiable with categorical syllogisms that have an implicit universal affirmative premise retrieved from semantic memory rather than explicitly stated. Previous studies with adult participants (Politzer, 2011) have shown that the rate of success is remarkably high. Because their resolution requires only the use of a simple strategy (known as ecthesis in classic logic) and an operational use of the concept of inclusion (the recognition that an element that belongs to a subset must belong to the set but not vice versa), it was hypothesized that these syllogisms would be within the grasp of non-adult participants, provided they have acquired the notion of deductive validity.

No problem for Aristotle's subject and predicate.

It is argued that, in the traditional subject-predicate sentence, two interpretations of the subject term coexist, one intensional and the other extensional, which explains the superficial difference between the traditional S-P relation and the predication of predicate logic. Data from psychological studies of syllogistic reasoning support the view that the contrast between predicate and argument is carried over to the traditional S-P sentence.