The notion of logical form and its applications are at the heart of some of the classical problems in philosophical logic and are the focus of Peter Long's investigations in the three essays that comprise this volume.

In the first, major, essay the concern is with the notion of logical form as it applies to arguments involving hypotethical statements, for example 'If today is Wednesday then tomorrow is Thursday; today is Wednesday: therefore tomorrow is Thursday.' Whilst such an argument (an argument by modus ponens) is cited by logical textbooks as a paradigm of one that is...