ABSTRACT
This chapter provides a sense of the disciplinary practices to which the expression "formal reasoning" refers and shows what people are referring to when they speak about formal reasoning. It explores how the formal approach to reasoning is applied to activities such as the game of checkers. Reasoning in checkers is valid formal reasoning like the reasoning in the derivation that Alfred receives good grades. One physical model of the formal system involves actual checkers, but this is only one model: someone, it seems, could be an excellent checker player without having ever played a game of checkers. The formal analysis of checkers is the analysis of a generic two-person game with rules. In fact, the analysis collects together the complete games that can be formulated in terms of that analysis. This generic analysis is fitted to checkers through its particular set of production rules and by including heuristic search procedures which may incorporate "expert knowledge."
