Full Idea
The single greatest difference between humans and other animals as far as rationality is concerned is our ability to create, recognise and act on desire-independent reasons for action.
Gist of Idea
The essence of humanity is desire-independent reasons for action
Source
John Searle (Rationality in Action [2001], Ch.1.II)
Book Reference
Searle,John R.: 'Rationality in Action' [MIT 2001], p.32