Full Idea
Experimentation is an occasional and more or less self-conscious exercise in what informal thinking does all the time without thinking about it.
Gist of Idea
An experiment is a deliberate version of what informal thinking does all the time
Source
Jerry A. Fodor (The Elm and the Expert [1993], §4)
Book Reference
Fodor,Jerry A.: 'The Elm and the Expert' [MIT 1995], p.99