People on the left call conservatives liars. People on the right call progressives liars. Are these two claims equivalent?
Philosophically, no. At least some kinds of conservatives still believe that truth is correspondence with reality, and that saying what you know to be false with the intention of deceiving is always wrong. This doesn’t mean they will never lie. What it means is that they think they shouldn’t. Whenever they do lie, their own creed accuses them.
From the beginning, however, the progressive movement has embraced pragmatism, a philosophy which is notoriously committed to the view that truth is whatever works. Certain kinds of conservatives, including the Law and Economics crowd, are strongly attracted to it too.
If truth is whatever works, then a lie is a lie only if it fails; if it succeeds, it isn’t a lie. It follows that although a pragmatist may sincerely agree that lying is wrong, for him this means only that he has to get away with it. If he does, then it worked, so he was telling the truth all along.
The drawback of this philosophy is that you won’t actually know whether or not you are lying until you either get caught or get away with it. So the way to avoid lying isn’t to avoid saying things that don’t correspond with reality, but to never get caught. Gather enough power to shut up your critics and make people believe what you say.
This also explains why certain political factions are so fond of the jeers “You’ve lost” and “You’re on the wrong side of history.” If truth is what works, those losers are liars by definition.
Considering the prevalence of vice, any politician might say whatever is expedient for gaining power. Viewing the matter objectively, though, which kinds of politician would you expect to do it more: The ones that believe in doing it, or the ones that don’t?