AbstractIn this article I give a unified account of three phenomena:bullshit,pseudoscienceandpseudophilosophy. My aims are partly conceptual, partly evaluative. Drawing on Harry Frankfurt's seminal analysis of bullshit, I give an account of the three phenomena and of how they are related, and I use this account to explain what isbadabout all three. More specifically, I argue that what is defective about pseudoscience and pseudophilosophy is precisely that they are special cases of bullshit. Apart from raising interesting philosophical issues, gaining a clearer understanding of these phenomena is also ofpracticalimportance, in that it bears on how best to tackle the threat that they pose.