The paradox of believing your own bullshit parallels the paradox of self-deception.  If a deceiver by definition knows that the belief he induces is false, it’s hard to see how he can convince himself that the selfsame belief is true (Hardcastle et. al. 2006, 10) ….  In his book Self Deception Unmasked (Princeton: Princeton University Press, 2001), Alfred Mele argues that self deception should not be understood on the model of interpersonal deception. In interpersonal deception, the deceiver does not believe the claim that he hopes his victim will accept as true. If self deception were to fit the interpersonal model, then the self-deceived person would have to play both roles, both affirming and denying the same belief. Mele takes this consequence to show that the interpersonal model fails. For self deception happens quite frequently, and belief in outright logical contradictions rarely seems involved. (Kimbrough, Scott. On Letting It Slide. In Bullshit and Philosophy (editors Hardcastle, Gary L. and Reisch, George A.). Chicago: Open Court; 2006; p. 10.)

Self deceived individuals “mask the evidence” and engage in a “motivated misinterpretation of evidence and selective evidence gathering.” For reasons of courtesy, strategy, and good evidence, we should criticize the product, which is visible, and not the process, which is not. (Frankfurt, p. 336) Warmed over bullshit is not merely a stale imitation of the original, but a fresh deposit that compounds the methodological faults of the original. (Ibid., p. 12-14.)

[B]ullshit results from the adoption of lame methods of justification, whether intentionally, blamelessly or as a result of self-deception. The function of the term is to emphatically express that a given claim lacks any serious justification, whether or not the speaker realizes it. By calling bullshit, we express our disdain for the speaker’s lack of justification, and indignation for any harm we suffer as a result. (Ibid., p. 16.)

[B]ullshit’s indifference to truth and falsity, its hidden interest in manipulating belief and behavior, and the way one senses, as Frankfurt put it in his book [On Bullshit], that the “bullshitter is trying to get away with something.” The audience had come to see Stewart and his writers skewer current political events, after all, so few would have missed the obvious referents—the absence of weapons of mass destruction in Iraq and the admission that sources for these claims were, in retrospect, not credible—that made the book so apropos. (Ibid., pp. viii-ix)

I always love that kind of argument. The contrary of a thing isn’t the contrary; oh, dear me, no! It’s the thing itself, but as it truly is. Ask any die-hard what conservatism is; he’ll tell you that it’s true socialism. And the brewers’ trade papers: they’re full of articles about the beauty of true temperance. Ordinary temperance is just gross refusal to drink; but true temperance, true temperance is something much more refined. True temperance is a bottle of claret with each meal and three double whiskies after dinner.

— Aldous Huxley, Eyeless in Gaza (London: Chatto and Windus, 1936) pp. 122–23.

Semantic Negligence

Bullshit is not the only sort of deceptive talk. Spurious definitions, such as those quoted above, are another important variety of bad reasoning. (Ibid., p. 151) …. Whereas the liar represents as true something he believes to be false, the bullshitter represents something as true when he neither knows nor cares whether it is true or false (On Bullshit, p. 55)…. [T]his indifference is much of what we find most objectionable about bullshit. The liar has a vested interest in the institution of truth-telling, albeit a parasitical one: he hopes that his falsehoods will be accepted as true. The bullshitter may also hope to be believed, but he himself is not much bothered whether what he says is true, hence his disregard for the truth is of a deeper and potentially more pernicious character. (Ibid., pp. 151-152)

Our outrage is conditioned on our being the objects of a deception. When we know what the bullshitter is up to we can be much more indulgent. As the comic novelist Terry Pratchett observes of two of his characters, “they believed in bullshit and were the type to admire it when it was delivered with panache. There’s a kind of big, outdoor sort of man who’s got no patience at all with prevaricators and fibbers, but will applaud any man who can tell an outrageous whopper with a gleam in his eye.” The gleam in the eye is essential here: it is this complicity between bullshitter and audience which constitutes the “bull session” (On Bullshit, p. 34). Only when it escapes from the bull session and masquerades as regular assertion is bullshit deceptive; however, the insidious nature of this deception degrades the commitment to truth upon which public discourse depends. (….) [The bullshitter’s] indifference as to the truth value of his statements, that is whether they are true or false, a meaning-related or semantic property, may thus be termed semantic negligence. (Ibid., p. 152)

Trump and the republican party has assaulted the concept of truth like nothing else in modern politics.

— Republican strategist Stuart Stevens in Amanpour and Company interview.