ABSTRACT
This chapter focuses on a few forms of valid arguments that are most frequently used by speakers and writers in ordinary contexts. Propositional logic is distinctive because it takes propositions or statements as basic units and examines how these units can be put together to produce valid arguments. Logical operators are used to construct new, compound, propositions out of simple propositions. The chapter reviews an area of logic, what is known variously as class logic, or Aristotelian logic, or classical logic, or as categorical logic. Immediate inferences are arguments that have only one premise. Three forms of immediate inference are: double negation, conversion, and the De Morgan laws. Two of hypothetical syllogisms modus ponens and modus tollens, allow one to derive a conclusion about either the antecedent or consequent of the hypothetical premise. The chapter also discusses an example of categorical logic to show how it differs from sentential or propositional logic.
