Children and undergraduate students were studied to expose "structure-neutral" interpretations of logical propositions involving universal affirmatives. Successes with true and false questions and with four different syllogistic forms having three content types were compared. Age-related differences in performance were discussed with…

Conservation judgments are based on a combination of logical necessity and empirical belief. Results of two experiments support the view that the logical aspect of conservation is developmentally stable, while the empirical aspect varies widely across problems and individuals because of its dependence on relevant experience. (Author/RD)