Full Idea
The difficulty of defining reason suggests that while pretending to use it to define the difference between humans and animals, they are actually using that difference to define reason.
Gist of Idea
Do we use reason to distinguish people from animals, or use that difference to define reason?
Source
Roger Scruton (Animal Rights and Wrongs [1996], p.19)
Book Reference
Scruton,Roger: 'Animal Rights and Wrongs' [Demos 1996], p.19
A Reaction
Too pessimistic. We are perfectly capable of saying there is no significant difference between us and an alien. We have obvious abilities, which we can partly specify.