To be "too smart by half" (also common is "
too clever by half") is to be too smart for one's own good, meant either literally or ironically. As an idiom, it is usually sarcastic. The phrase has a wide range of potential uses; for instance, it can mean:
1.) Something so complex that it's self-obfuscating.
2.) A seemingly clever action that is in fact foolish.
3.) Logically accepting something as necessary that isn't.
4.) Overanalysis.
5.)
Elitism (see
ivory tower).
--"Those
Harvard scholars are too smart by half."
--"What a dumb
idea; I tell you, that guy is too smart by half."