Abstract

This paper argues that Lemmon-style proof systems (those that consist of only introduction and elimination inference rules) have several pedagogical benefits over Copi-style systems (those that make use of inference rules and equivalence rules). It is argued that Lemmon-style systems are easier to learn as they do not require memorizing as many rules, they do not require learning the subtle distinction between a rule of inference and a rule of replacement, and deriving material conditionals is more straightforward. Finally, it is argued that the need for learning provisional assumptions in Lemmon-style rules is not a significant enough reason for choosing the Copi-style system.