The following proposition seems to me in a high degree probable—namely, that any animal whatever, endowed with well-marked social instincts, the parental and filial affections being here included, would inevitably acquire a moral sense or...

What we now call “morality” was evolved – as nearly all social and physical human attributes were – to aid us in survival and, ultimately, reproduction. This morality requires only that we be guided by...

The practice of that which is ethically best—what we call goodness or virtue—involves a course of conduct which, in all respects, is opposed to that which leads to success in the cosmic struggle for existence....