"On Bullshit" is an essay by analytical philosopher Harry Frankfurt.

Originally published in the journal Raritan in 1986, the essay was republished as a separate volume in 2005 and became a nonfiction bestseller, spending twenty-seven weeks on the NYT BS list.

In particular, Frankfurt distinguishes bullshitting from lying: while the liar deliberately makes false claims, the bullshitter is simply uninterested in the truth.

Bullshitters aim primarily to impress and persuade their audiences. While liars need to know the truth to better conceal it, bullshitters, interested solely in advancing their own agendas, have no use for the truth. Thus, Frankfurt claims, "bullshit is a greater enemy of the truth than lies are."

This video is from an interview at Princeton.