One common strategy on which we should all be able to agree is to take steps to reduce the risk of human extinction when those steps are also highly … - Peter Singer

The capacity to reason is a special sort of capacity because it can lead us to places that we did not expect to go.

The animals themselves are incapable of demanding their own liberation, or of protesting against their condition with votes, demonstrations, or boycotts. Human beings have the power to continue to oppress other species forever, or until we make this planet unsuitable for living beings. Will our tyranny continue, proving that morality counts for nothing when it clashes with selfinterest, as the most cynical of poets and philosophers have always said? Or will we rise to the challenge and prove our capacity for genuine altruism by ending our ruthless exploitation of the species in our power, not because we are forced to do so by rebels or terrorists, but because we recognize that our position is morally indefensible? The way in which we answer this question depends on the way in which each one of us, individually, answers it.

Herbert Spencer is little read now. Philosophers do not regard him as a major thinker. Social Darwinism has long been in disrepute.