For years I've grappled with a dilemma which is really only relevant to people who want to argue with Objectivists. Basically once you claim to live by a selfish code of ethics, what prevents you from violating the rights of others for personal gain, in situations where you know you will not be at risk?
David Friedman calls this the Prudent Predator dilemma, and he's been twisting up Randroids with it for 40 years. He even got me with it, back in the day, when I was basically trying to re-write Objectivism into something that made sense.
“Ethics, empathy, and primate brain holdovers [1]”
I wish I knew of this argument a decade ago when a few of my friends fell heavily into Objectivism. In trying to understand them, I even read all zillion pages of Atlas Shrugged [2] (neat story, but she could have used an editor).
The entry also points out some recent research showing that there may be a biological component to society. Read, as they say, the whole thing.