Full Idea
A full-grown horse or dog is beyond comparison a more rational animal than an infant of a day, or even a month, old. But suppose they be otherwise, what would it avail? The question is not, Can they reason? nor Can they talk? but, Can they suffer?
Gist of Idea
Large mature animals are more rational than babies. But all that really matters is - can they suffer?
Source
Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], XVIII 1 n), quoted by Peter Singer - Practical Ethics 03
Book Reference
Singer,Peter: 'Practical Ethics' [CUP 1989], p.50
A Reaction
This is certainly an inspiring, and even shocking question, which never seems to have been so directly asked before in the entire history of European thought. Awesome.