Memetic Immune System
Intelligent people sometimes do things more stupid than stupid people are capable of. There are a variety of reasons for this; but one has to do with the fact that all cultures have dangerous memes circulating in them, and cultural antibodies to those memes. The trouble is that these antibodies are not logical. On the contrary; these antibodies are often highly illogical. They are the blind spots that let us live with a dangerous meme without being impelled to action by it. The dangerous effects of these memes are most obvious with religion; but I think there is an element of this in many social norms. We have a powerful cultural norm in America that says that all people are equal (whatever that means); originally, this powerful and ambiguous belief was counterbalanced by a set of blind spots so large that this belief did not even impel us to free slaves or let women or non-property-owners vote. We have another cultural norm that says that hard work reliably and exclusively leads to success; and another set of blind spots that prevent this belief from turning us all into Objectivists.
-Phil Goetz, Reason as memetic immune disorder