Location

Brock University

Document Type

Paper

Start Date

15-5-1997 9:00 AM

End Date

17-5-1997 5:00 PM

Abstract

The distinction between formal and informal logic is clarified as a prelude to considering their ideal relation. Aristotle's syllogistic describes forms of valid inference, and is in that sense a formal logic. Yet the square of opposition and rules of middle term distribution of positive or negative propositions in an argument's premises and conclusion are standardly received as devices of so-called informal logic and critical reasoning. I propose a more exact criterion for distinguishing between formal and informal logic, and then defend a model for fruitful interaction between informal and formal methods of investigating and critically assessing the logic of arguments.

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This work is licensed under a Creative Commons Attribution 4.0 License.

Response to Submission

Hans V. Hansen, Commentary on Jacquette

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Hans V. Hansen, Commentary on Jacquette (May 1997)

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May 15th, 9:00 AM May 17th, 5:00 PM

On the Relation of Informal to Formal Logic

Brock University

The distinction between formal and informal logic is clarified as a prelude to considering their ideal relation. Aristotle's syllogistic describes forms of valid inference, and is in that sense a formal logic. Yet the square of opposition and rules of middle term distribution of positive or negative propositions in an argument's premises and conclusion are standardly received as devices of so-called informal logic and critical reasoning. I propose a more exact criterion for distinguishing between formal and informal logic, and then defend a model for fruitful interaction between informal and formal methods of investigating and critically assessing the logic of arguments.