ABSTRACT
During the sixteenth and seventeenth centuries, the terms dialectic and logic were frequently used interchangeably. When speaking more strictly, however, philosophers often distinguished between the two on the Aristotelian ground that the former dealt with deductive inference from first principles that were accepted only as being probable, whereas the latter dealt with deductive inference from first principles that were accepted as certain. In both cases, the conclusions arrived at by such inference were themselves as solidly established as the premises from which they were derived.
