The study of categorical propositions reveals how inferences can be made
conclusively. If the form of an argument is valid and the premisses are true,
the conclusion follows with absolute certainty.
Take some care with the logical relations called contrariety and
subcontraiety. For some persons, these inferences are initially counterintuitive.
Links to Lecture Notes…
Quality, and Distribution
The properties of standard form categorical
propositions are explained
- The Square
The logical relations of contradictory,
contrariety, subcontrariety, and
subalternation are explained and illustrated.
The Square of Opposition is reviewed, and three
additional inferences are
explained and illustrated: conversion, obversion, and contraposition.
The following exercises are taken from Irving M.
Copi and Carl Cohen, Introduction to Logic
for Successive Inferences
The technique of successive applications of logical relations drawn from the
square of opposition and further immediate inferences is discussed and
Three ordinary language examples of using immediate inferences demonstrate the
uses of standard form categorical propositions and their logical relations.
The technique of representing statements by means of pictures is explained.