ABSTRACT
The chapter discusses immediate and mediate inferences in turn, and begins with traditional treatments of each and then proceeding to consider more modern developments in these treatments. Deductive inferences were traditionally divided into immediate inferences and mediate inferences. The square of opposition indicates that the relation underlying this inference is that of contradiction. The aim of the traditional theory of immediate inferences was to specify a set of operations by which it would be possible to move from any single statement in the appropriate form to every statement which could be inferred from it alone. The possible conversions are determined by the distribution of the terms in the original statement and our principle of deductive inference. Conversion and obversion are very simple and seem obviously valid. Contraposition and inversion depend only upon conversion and obversion.
