Toward a logic for fuzzy syllogisms

The author describes a formal logic that encodes the reasoning embodied in syllogisms of the form. `Most birds can fly; Tweety is a bird; therefore, it is likely that Tweety can fly,´ and of the form, `Usually, if something is a bird, it can fly; Tweety is a bird; therefore, it is likely that Tweety can fly.´ More exactly, he defines a formal language in which syllogisms of these and related forms can be expressed, and then this language is provided with a rigorously defined semantics in which such syllogisms are valid. In the process a general approach is established to formalize the notions of fuzzy quantification, usuality, and likelihood. Some of the interrelations between these concepts that are expressible in this formalism are also explored