Why political philosophy might be legitimate anyway
People who don't agree with me that there's nothing metaphysically dodgy about talking about moral facts and properties mostly fall into two camps. There are the error theorists on the one hand and the non-cognitivists on the other.
Error theorists think, roughly speaking, that our moral claims could in principle be true, but that as a matter of fact they never are. That is: they think that moral discourse (talking about moral shoulds and shouldn'ts etc.) should be taken at face value as making claims about real moral facts and properties—but, they argue, there are no real moral facts and properties. They think it's false that killing is wrong, because there's no such thing as wrongness. But they also think it's false that killing is permissible, because there's no such thing as permissibility.
Non-cognitivists don't take our moral discourse at face value. They think, roughly speaking, that what's going on when we make moral claims is that we're actually expressing some kind of feeling, such as a feeling of pleasure (when we approve) or a feeling of pain (when we disapprove). According to non-cognitivists, it just looks as if claims such as "killing is wrong" are of the same kind as claims such as "tennis balls are bouncy" and "eating a lot makes you fat". But that's not what they're really like.
Hide this ⇧
Now, non-cognitivists are much more common—yet they typically think it's perfectly acceptable to carry as if our moral claims are capable of being true and false. At the fundamental level, of course, they think that this isn't how things are. But they aim to vindicate our ordinary practices by re-interpreting claims such as "killing is wrong" as expressions of non-cognitive attitudes (such as dislikings or commandings), and so not really truth-apt, and then proposing a semantics of such expressions that makes sense of the way we use them ordinarily.
Truth-aptness Some of our utterances are 'truth-apt'. It makes sense to ask whether they're true or false. Others, though, aren't truth-apt. If you asked whether such utterances were true or false, you would be making a mistake about what kind of utterance you'd heard.
For example: questions are not truth-apt. You can tell that they're not truth-apt from the fact that it makes no sense to tell someone that her question was false. How could a question be false?
Other examples of utterances which aren't truth-evaluable:
- Cries of pain (e.g. "Ow!")
- Shouts of pleasure (e.g. "Hooray!")
- Commands (e.g. "Go home!")
- Salutations (e.g. "Hello!")
Assertions, predictions, recollections, and a range of other utterances, on the other hand, are truth-apt. It does make sense to ask whether they're true.
Some mental states (e.g. beliefs) are most accurately or naturally expressed by truth-apt utterances. But other mental states (e.g. pain) are most accurately or naturally expressed by non-truth-apt utterances.
Semantics To propose a semantics is to give an account of the meanings of expressions or terms. The semantics of truth-apt expressions tells us what the conditions are under which they're true, and that helps us to understand why you can't coherently say "The earth is spherical, but it is not the case that the earth is spherical", for example.
If moral discourse were truth-apt, then its semantics would be just like that of non-moral truth-apt discourse, such as discourse about the shape of the earth. And so the reason that it seems incoherent to say "Killing is wrong but it is not the case that killing is wrong" would be the same as the reason that it's incoherent to say "The earth is spherical but it is not the case that the earth is spherical."
However, if moral discourse is not truth-apt, as non-cognitivists suppose, then the explanation of the apparent incoherence of "Killing is wrong but it is not the case that killing is wrong" will have to be different. So a different semantics—a different account of the meanings of moral expressions, one that can make sense of the apparent incoherence—will be needed.
Hide this explanation ⇧
So, most non-cognitivists are like moral realists in that they think it's fine for us to carry on making and arguing about moral claims pretty much as we do already. And it doesn't seem obviously to be a mistake to try to vindicate those practices in this way. Why should we abandon them, after all? Like any other human practice, they may have their point. It's just that at the meta-ethical level, non-cognitivists have a particular view about how we should conceive of what's going on when we engage in them.
Error theorists, on the other hand, are a bit rarer. Now, some of them don't think it's okay for us to carry on making and arguing about moral claims as before. They think our moral discourse is wholly misconceived. But there are others who think (possibly incoherently!) that the practice has a value that makes it worth sticking with, despite the fact that it tries to refer to non-existent facts and properties.
And of course it goes without saying that realists have many arguments against both non-cognitivists and error theorists.
What this shows is that even if you're sceptical about moral facts and properties, that doesn't mean that what we do in political philosophy isn't legitimate. For you could be like the non-cognitivists or some of the error theorists, and understand our moral discourse as something which doesn't need to involve true claims to be legitimate.
Either way, I hope that it's clear that you need to do quite a lot of philosophical work before you can simply dismiss what we do in political philosophy. You need to show that I'm wrong to reject your reasons for scepticism. And you need to show that the right way to go is error theory rather than some form of non-cognitivism.