Clearly when the liberties are left unrestricted they collide with one another.

The principles of justice are chosen behind a veil of ignorance.

First of all, principles should be general. That is, it must be possible to formulate them without use of what would be intuitively recognized as proper names, or rigged definite descriptions.

The circumstances of justice may be described as the normal conditions under which human cooperation is both possible and necessary.

There are two kinds of comprehensive doctrines, religious and secular. Those of religious faith will say I give a veiled argument for secularism, and the latter will say I give a veiled argument for religion. I deny both. Each side presumes the basic ideas of constitutional democracy, so my suggestion is that we can make our political arguments in terms of public reason. Then we stand on common ground. That's how we can understand each other and cooperate.

Public reason arguments can be good or bad just like other arguments.

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.