Canadian Journal of Philosophy, 26, pp. 333-66. 1996.

I sketch in miniature the whole of my work on the relation between language and thought. Previously I have offered closeups of this terrain in various papers and books, and I reference them freely. But my main purpose here is to explain the relations among the parts, hoping this can serve as a short introduction to my work on language and thought for some, and for others as a clarification of the larger plan.

Two theories of propositional deductive reasoning are considered: the mental models of P. N. Johnson-Laird et al and the mental logic of M. D. Braine. The model theory is said to account for practically all of the known phenomena of deductive propositional reasoning, offer a general theory of conditionals, account for the most important aspects of Braine's theory, and predict new phenomena that rule theories cannot explain. It is argued that the model theory is flawed in a way that is (...) difficult to overcome, conditionals are seriously misrepresented, the algorithms proposed to implement it either allow invalid inferences or are psychologically useless, Braine's theory accounts for all of the new phenomena worth considering, and the model theory can predict Braine's results only at the cost of self-refutation. It is concluded that the mental model theory of propositional reasoning offers no reason to reject the program of mental logic. (shrink)

This paper examines geometrical arguments from Galileo's Mechanics and Two New Sciences to discern the influence of the Aristotelian Mechanical Problems on Galileo's dynamics. A common scientific procedure is found in the Aristotelian author's treatment of the balance and lever and in Galileo's rules concerning motion along inclined planes. This scientific procedure is understood as a development of Eudoxan proportional reasoning, as it was used in Eudoxan astronomy rather than simply as it appears in Euclid's Elements. Topics treated include the (...) significance of the circle in Galileo's demonstrations, the substitution of rectilinear elements for heterogeneous factors like weight and curvilinear distance, and the way in which elements of a motion are used to measure other elements of the same motion. The indirectness of Galileo's proofs, his conception of speed as relative and comparative, and the meaning of his concept of moment all come into clearer focus. Conclusions are drawn about Galilean idealization, and also about the contrast of literal versus figural modes of explanation in Galileo's science. (shrink)