Full Idea
Rules of deduction are rules of deductive argument; they are not rules of inference or reasoning.
Gist of Idea
The rules of reasoning are not the rules of logic
Source
Gilbert Harman (Change in View: Principles of Reasoning [1986], 1)
Book Reference
Harman,Gilbert: 'Change in View: Principles of Reasoning' [MIP 1986], p.5
A Reaction
And I have often noticed that good philosophing reasoners and good logicians are frequently not the same people.
Related Idea
Idea 3094 You don't have to accept the conclusion of a valid argument [Harman]