"Bullshit" is the title of a well-known 1986 essay by Princeton philosopher Harry Frankfurt, now expanded into a short book.
Two of Frankfurt's main points seem to be that, 1, the bullshitter is more motivated to create an impression of himself rather than to communicate substantial true material and 2. bullshit may be more insidious than lying. From a review of the book here:
...bullshitters seek to convey a certain impression of themselves without being concerned about whether anything at all is true. They quietly change the rules governing their end of the conversation so that claims about truth and falsity are irrelevant. Frankfurt concludes that although bullshit can take many innocent forms, excessive indulgence in it can eventually undermine the practitioner's capacity to tell the truth in a way that lying does not. Liars at least acknowledge that it matters what is true. By virtue of this, Frankfurt writes, bullshit is a greater enemy of the truth than lies are.
Besides being a very bright fellow, his life as an academic gives him unique experience with the world of bullshit. We are all bullshitters, to some extent, but some make a career of it.
Frankfurt's original 6-page essay can be read here. One quote:
It is impossible for someone to lie unless he thinks he knows the truth. Producing bullshit requires no such conviction. A person who lies is thereby responding to the truth, and he is to that extent respectful of it. When an honest man speaks, he says only what he believes to be true; and for the liar, it is correspondingly indispensable that he considers his statements to be false. For the bullshitter, however, all these bets are off: he is neither on the side of the true nor on the side of the false. His eye is not on the facts at all, as the eyes of the honest man and of the liar are, except insofar as they may be pertinent to his interest in getting away with what he says. He does not care whether the things he says describe reality correctly. He just picks them out, or makes them up, to suit his purpose.
