The gradually increasing levels of harmful obedience in the milgram's social psychology experiments best illustrates one of the potential dangers of

The correct answer is the foot-in-the-door phenomenon.

The foot-in-the-door (FITD) phenomenon refers to a compliance technique in which you can get someone to do something big for you if they agree to do something small for you first. In Milgram's experiment, by getting participants to initially  administer low voltage electric shocks to the stooge, he gradually managed to get participants to administer gradually higher and higher voltage shocks, thus, illustrating the harmful effects of the foot-in-the-door phenomenon.