Full Idea
The most dramatic manifestation of the free will gap is that when one has several reasons for performing an action, one may act on only one of them; one may select which reason one acts on.
Gist of Idea
Free will is most obvious when we choose between several reasons for an action
Source
John Searle (Rationality in Action [2001], Ch.3.II)
Book Reference
Searle,John R.: 'Rationality in Action' [MIT 2001], p.65