Informal logic

the long version

In this insightful critique of informal logic and critical thinking strategies and techniques, Wayne Grennan examines argument evaluation techniques currently used in both formal and informal logic texts and, finding them lacking, proposes a new system of evaluation. Concluding that informal logic texts do not encourage precision in evaluating arguments, Grennan proposes a new argument evaluation procedure that expresses judgments of inferential strength in terms of probabilities. Based on theories of Stephen Toulmin, Roderick Chisholm, and John Pollock, his proposed system allows for a more precise judgment of the persuasive force of arguments.