kant on lying

on a related note

There is a famous argument in Kant's Groundwork for the Metaphysics of Morals which purports to show why the categorical imperative (act only on that maxim you can will as a universal law of nature) dictates that we do not lie. It tries to show that a world in which everyone lies to attain their ends is not a coherent one. That is, if I know you're going to lie to me, you can't lie to me.

But things are trickier than this. After all, the essence of lying does not consist in intentionally making false statements. If that were the case, then the world where we all lie would be straightforwardly pointless. But things are trickier. For example, if I know that you know that I'll lie to you (and you do not know this), then if I make a true statement, you'll believe it to be false and thus believe it's negation - and I will have succeeded in deceiving you.

Of course, if everyone knows that everyone lies, and we recurse this as far as it goes (forever), then things are much trickier. That is, there is no equilibrium. Consider: if I know that you know that I intend to lie to you and I also know that you know that I know that you know, but you don't know that, then telling a false statement will get you to believe the false thing. But if we never hit an item of knowledge that one of us knows and the other doesn't, then there is no straightforward answer as to what to do. It's a lot like playing rock-paper-scissors.

What all this means, actually, is that words would - at least from one perspective - lose their meaning (it is perhaps in this sense that the world is incoherent). After all, in such a situation, sentences would be treated as merely causal objects by everyone - we'd all know that everyone's utterances are responsive not to the truth, but to their causal effects on the world (e.g. us). And if that's the case, then sentences wouldn't mean anything.

This does not mean that such a world is incoherent - at least I don't think so. It just means that we'd all be treating each other as mere means, as merely causal objects. Meaning, normativity, right and wrong - well beyond merely moral matters - would drop out.

(This is as far as I've thought things through).