How to Make Our Ideas Clear

Introduction

The essay appeared in January 1878 in Popular Science Monthly, as the second part of a series titled “Illustrations of the Logic of Science”, after “The Fixation of Belief”. Peirce distinguishes grades of clarity: familiarity with a concept, abstract definition and, highest of all, knowledge of its conceivable practical effects. His examples include hardness, weight and force – and the Catholic doctrine of transubstantiation, which, he argues, has no effects that would distinguish it from its denial. The essay also defines truth as the opinion that all who investigate are fated ultimately to agree on. The word “pragmatism” does not yet appear; William James made the maxim famous in a lecture of 1898 and credited Peirce with it.

Connections

Builds on

• Some Consequences of Four Incapacities1868 · Charles Sanders Peirce

Taken up in

• Pragmatism1907 · William James
• Knowledge and Human Interests1968 · Jürgen Habermas

More works by Charles Sanders Peirce

• 1868Some Consequences of Four Incapacities