Certainly it is wrong to be cruel to animals and the destruction of a whole species can be a great evil. The capacity for feelings of pleasure and pain and for the form of life of which animals are capable clearly impose duties of compassion and humanity in their case.
John RawlsProperly understood, then, the desire to act justly derives in part from the desire to express most fully what we are or can be, namely free and equal rational beings with the liberty to choose.
John Rawls