Austin tried to cut through the unsatisfying vagueness of the natural law tradition with some crisp definitions.
We converted some of these to necessary and sufficient conditions in order to see how Hart challenged them.
In particular, we focused on two cases:
- whether being a command is a necessary condition of being a law and
- whether threatening someone is a sufficient condition of that person’s having an obligation.
How do these arguments work?
How do you argue about definitions? That’s a darn good question, posed by the gentleman on my left (sorry, I’m going to do names next week).
Well, in a sense, you don’t. If Austin defines a law as a command, then he is free to say that nothing that isn’t a command could be a law, as he uses the word. And it would be fruitless to deny it. It is how he’s using the term, after all.
The way to dispute a definition is to challenge its relevance. The threat to definitions isn’t usually inconsistency, it’s irrelevance.
Hart is trying to show that legal systems as we know them do not fit Austin’s definitions. I think the best way to understand what he’s doing is that he’s challenging the relevance of Austin’s definitions to the legal systems that we want to understand: the real ones.