Thus the Dustin Hoffman character in Hero. "There ain't no truth; all there is, is bullshit." (HT: Vlastimil V.) This very short video clip would be a good way to get your intro to phil students thinking about truth. Some questions/issues:
1. Is it true that there is no truth? If yes, there there is at least one truth. If no, then there is at least one truth. Therefore, necessarily, there is at least one truth. This simple reflection may seem boring and 'old hat' to you, but it can come as a revelation to a student.
2. What exactly is bullshit? Is a bullshit statement one that is false? Presumably every bullshit statement is a false statement, but not conversely. There are plenty of false statements that are not bullshit. So the property of being bullshit is not the property of being false. Nor is it the property of being meaningless, or the property of being self-contradictory.
3. In ordinary English, 'bullshit' is often used to describe a statement that is plainly false, or a statement that one believes is plainly false, or one that either is or is believed to be a lie. But none of these uses get at the 'essence' of bullshit.
4. So when is a statement bullshit?
According to Harry Frankfurt, a statement is bullshit if it is
. . . grounded neither in a belief that it is true nor, as a lie must be, in a belief that it is not true. It is just this lack of connection to a concern with truth — this indifference to how things really are — that I regard as of the essence of bullshit." (emphasis added)
Professor Frankfurt has a fine nose for the essence of bullshit. The bullshitter is one who 'doesn't give a shit' about the truth value of what he is saying. He doesn't care how things stand with reality. The liar, by contrast, must care: he must know (or at least attempt to know) how things are if he is to have any chance of deceiving his audience. Think of it this way: the bullshitter doesn't care whether he gets things right or gets them wrong; the liar cares to get them right so he can deceive you about them.
Now if the bullshitter does not care about truth, what does he care about? He cares about himself, about making a certain impression. His aim is to (mis)represent himself as knowing what he does not know or more than he actually knows. Frankfurt again:
. . . bullshitting involves a kind of bluff. It is closer to bluffing, surely than to telling a lie. But what is implied concerning its nature by the fact that it is more like the former than it is like the latter? Just what is the relevant difference here between a bluff and a lie? Lying and bluffing are both modes of misrepresentation or deception. Now the concept most central to the distinctive nature of a lie is that of falsity: the liar is essentially someone who deliberately promulgates a falsehood. Bluffing too is typically devoted to conveying something false. Unlike plain lying, however, it is more especially a matter not of falsity but of fakery. This is what accounts for its nearness to bullshit. For the essence of bullshit is not that it is false but that it is phony. In order to appreciate this distinction, one must recognize that a fake or a phony need not be in any respect (apart from authenticity itself) inferior to the real thing. What is not genuine need not also be defective in some other way. It may be, after all, an exact copy. What is wrong with a counterfeit is not what it is like, but how it was made. This points to a similar and fundamental aspect of the essential nature of bullshit: although it is produced without concern with the truth, it need not be false. The bullshitter is faking things. But this does not mean that he necessarily gets them wrong. (emphasis added)