I enjoyed reading Formal Ethics, a textbook by Harry J. Gensler. The basic gist is that he formalizes the Golden Rule from some simpler axioms. From my error-pr

I enjoyed reading Formal Ethics, a textbook by Harry J. Gensler. The basic gist is that he formalizes the Golden Rule from some simpler axioms. From my error-prone memory, the four axioms were along the lines of: 1. If you ought to do something, then do it (aligning belief with action), 2. If something ought to be done, then a relevantly identical something also ought to be done (universalizability), 3. One ought to think and live consistently with logic (rationality), and 4. If one is in favor of an outcome, one should be in favor of the outcome's prerequisites (ends and means). From that you get to concepts like consistency, conscientiousness, impartiality, and eventually the stricter form of the golden rule (which encompasses both "do unto others what you'd have done to you" and "don't do unto others what you wouldn't have done to you"). There's a cool looking symbolic logic version of it, too. My wife and I put it on our wedding poster. :) Anyway, to echo other commenters here - it's not so hard to come up with ethical axioms (opinions/values) that are widely shared. The challenge is in keeping the reasoning consistent after that point.