For most people, the fact that a statement is false constitutes in itself a reason, however weak and easily overridden, not to make the statement. For Saint Augustine’s pure liar it is, on the contrary, a reason in favor of making it. For the bullshitter it is in itself neither a reason in favor nor a reason against. Both in lying and in telling the truth people are guided by their beliefs concerning the way things are. These guide them as they endeavor either to describe the world correctly or to describe it deceitfully. For this reason, telling lies does not tend to unfit a person for telling the truth in the same way that bullshitting tends to. Through excessive indulgence in the latter activity, which involves making assertions without paying attention to anything except what it suits one to say, a person’s normal habit of attending to the ways things are may become attenuated or lost. Someone who lies and someone who tells the truth are playing on opposite sides, so to speak, in the same game. Each responds to the facts as he understands them, although the response of the one is guided by the authority of the truth, while the response of the other defies that authority and refuses to meet its demands. The bullshitter ignores these demands altogether. 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 the truth than lies are.

One who is concerned to report or to conceal the facts assumes that there are indeed facts that are in some way both determinate and knowable. His interest in telling the truth or in lying presupposes that there is a difference between getting things wrong and getting them right, and that it is at least occasionally possible to tell the difference. Someone who ceases to believe in the possibility of identifying certain statements as true and others as false can have only two alternatives. The first is to desist both from efforts to tell the truth and from efforts to deceive. This would mean refraining from making any assertion whatever about the facts. The second alternative is to continue making assertions that purport to describe the way things are, but that cannot be anything except bullshit.

-Harry G. Frankfurt, On Bullshit

You first have to revise the question. To ask why is to ask for a motive or a purpose. And a motive has to arise from an apparatus capable of framing an intention, which is normally what we call a mind. Thus the question why is always really the question who.

Barbara Ehrenreich, Living with a Wild God