I think Zimbardo's biggest contribution ever has been grossly overlooked. He made the point after Milgrams experiment that everyone who disobeyed authority and

I think Zimbardo's biggest contribution ever has been grossly overlooked. He made the point after Milgrams experiment that everyone who disobeyed authority and stopped injuring the victim still required permission (from the authority that just had them injuring someone) to help their victim. It's not only that you can create little lucifers, but it's that you wholly prevent the good Samaritan ever appearing.