  However, this understanding of concept possession has drawbacks. Perhaps the biggest source of concern in the present context is that this sort of view fuels a version of Dworkin’s “semantic sting” argument (Dworkin 1986, 43–46). The argument may be summarized as follows. Suppose legal theories aim to capture the concept of law and that concept possession just is a matter of knowing when the word “law” applies. If so, the argument runs, legal theories cannot explain disagreement about the grounds of law, that is, about the conditions of legal validity. After all, if legal theories are in this way semantic in nature, then disagreement about what the grounds of law are must boil down to disagreement about when the word “law” applies—at least assuming the parties to the disagreement are not merely talking past one another. But now a dilemma arises. Either legal practitioners possess the same concept of law or they do not. If they do possess the same concept, then it seems they cannot fail to agree about what it takes for a norm to count as law. After all, they all know when the word expressing their shared concept of law applies. But this is implausible, since legal practice in fact is rife with disagreement about what the grounds of law are (and thus, what counts as law or as legal). On the other hand, if legal practitioners do not share the same concept of law, then their disagreement about what the grounds of law are must just be due to the fact that they are talking past one another. But that, too, is implausible. Legal practice, as Dworkin puts it, is not “a grotesque joke” (Dworkin 1986, 44). Accordingly, there must be something wrong with construing legal theories as mere semantic accounts of when the word “law” applies.