The 1986 article "On Bullshit" was known only to philosophical initiates until 2005 when, in a timely marketing move, it was published as a teeny-tiny book by Princeton University Press and found its way into the very short list of bestselling books written by philosophers. Others have cashed in since then, including the Popular Culture and Philosophy series at Open Court, with a whole collection of essays on Bullshit and Philosophy (see Rob Loftis' comment here).
Frankfurt distinguishes bullshit from lying. Liars know the truth and take some pains to conceal it, whereas bullshitters lack any sort of connection to or concern about truth: "this indifference to how things really are...[is]...the essence of bullshit." The bullshitter's "speech is empty, without substance or content." It is trivial; it is insincere. The bullshitter has his own motives, and in pursuing his goals, truth is a casualty. He does not even care about truth enough to lie. The evidence supporting a claim has nothing to do with the reasons why it should be accepted, for a bullshitter. And in virtue of paying no attention to the claims of reason and logic, "bullshit is a greater enemy of the truth than lies are."
My Critical Thinking class has taken one day to discuss this book, and we'll discuss it more today. I asked for examples of BS and the students came up with the usual examples from marketing and business. Several also had some sharp political insights (more about that tomorrow). And there was the predictably cynical comment that the essay was nothing but a performative confirmation that philosophy itself is nothing but BS.
But the comment that made me chuckle loudest was that
"Scientology is the biggest load of BS that God ever created."