I heard about the "Harm Principle" while reading some comments on some post on some blog from 2007 sometime. "The harm principle is articulated most clearly in John Stuart Mill's On Liberty." from Wikipedia. It is related to "The Ethic of Reciprocity." It piqued my interest and I started doing some research. The first thing I noticed is that it's something that has been around and advocated by the most influential religions from millienia ago. The Harm Principle takes up similar forms.
Confucius say, "Never impose on others what you would not choose for yourself?"
Analects XV.24, tr. David Hinton
Do not do unto others what angers you if done to you by others. -Isocrates 436-338 BCE
Hillel was challenged by a potential convert to Judaism to teach him the whole Torah while he stood on one leg. Hillel replied, “That which is hateful to you, do not do to others.”
Jesus said in Matthew 7:12, Luke 6.31 said, "In all things whatsoever ye would that men should do to you, do ye even so unto them."
This is the sum of duty: do naught to others which if done to thee would cause thee pain. -The Mahabharata (Hindu)
Hurt not others with that which pains yourself. -Udana-Varga (Buddhist)
No one of you is a believer until he desires for his that which he desires for himself. -Hadith
He should not wish for others that which he doth not for himself, nor promise that which he doth not fulfil. -The Book of Certitude (Bahai)
"An it harm none, do what ye will." Wiccan Rede
Steve Pinker said,"...the inexorable logic of the golden rule: The more one knows and thinks about other living things, the harder it is to privilege one's own interests over theirs. The empathy escalator may also be powered by cosmopolitanism, in which journalism, memoir, and realistic fiction make the inner lives of other people, and the contingent nature of one's own station, more palpable—the feeling that "there but for fortune go I.""