Thus begins Princeton University Professor of Philosophy Emeritus Harry Frankfurt's essay, On Bullshit, an academic inquiry into the nature of what exactly constitutes "bullshit." This piece, recently released in book form, should be on the bookshelf of every person who values the notion that there is such a thing as objective truth.
The essay is important because Frankfurt brings to light an insightful observation about the nature of bullshit, that "the essence of bullshit is not that it is false but that it is phony." Frankfurt moves from this premise to point out that where as a liar works to hide the truth and his intent to not tell it, what the bullshitter seeks to hide "is that the truth-value of his statements are of no central interest to him; what we are not to understand is that his intention is neither to report the truth nor to conceal it."
For Frankfurt, the distinguishing feature of bullshit is not that it is true or that it is false, but that it is constructed with a complete disregard for what the facts might be; and what's worse, where the liar knows that what he is saying is not true, the bullshitter might actually sincerely believe what he is saying. It is for this reason that bullshit is so dangerous, because, as he notes, people have a tendency to allow sincerity to substitute for accuracy. Frankfurt's description of the bullshitter concisely makes this point
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 ... He does not care whether the things he says describe reality correctly. He just picks them out, or makes them up, to suit his purposes ... He does not reject the authority of the truth, as the liar does, and oppose himself to it. He pays no attention to it at all. By virtue of this, bullshit is a greater enemy of truth than lies are.