Full Idea
The mental operations concerning in reasoning are three. The first is Observation; the second is Experimentation; and the third is Habituation.
Gist of Idea
Reasoning involves observation, experiment, and habituation
Source
Charles Sanders Peirce (Reasoning and the Logic of Things [1898], V)
Book Reference
Peirce,Charles Sanders: 'Reasoning and the Logic of Things', ed/tr. Ketner,K.L. [Harvard 1992], p.182
A Reaction
I like the breadth of this. Even those who think scientific reasoning has priority over logic (as I do, thinking of it as the evaluation of evidence, with Sherlock Holmes as its role model) will be surprised to finding observation and habituation there.