"The test of a first-rate intelligence is the ability to hold two opposed ideas in mind at the same time and still retain the ability to function." (F. Scott Fitzgerald)

I've also noticed something about the term "cognitive dissonance" in popular discussion. It's used as a pejorative explanation when the speaker can't figure out how someone else harmonizes two apparently inconsistent or contradictory positions. But when it's a speaker responding to someone else's accusation of cognitive dissonance, something like Fitzgerald's line usually comes up.

It's probably a useful concept in the context of doing actual psychology (either science or therapy), but I've come to believe that in an argument it's often a form of ad hominem attack, like most stories participants in arguments tend to spin about each other.