To those who say "Nothing is real," I once replied, "That's great, but how does the nothing work?"
Suppose you learned, suddenly and definitively, that nothing is moral and nothing is right; that everything is permissible and nothing is forbidden.
Devastating news, to be sure—and no, I am not telling you this in real life. But suppose I did tell it to you. Suppose that, whatever you think is the basis of your moral philosophy, I convincingly tore it apart, and moreover showed you that nothing could fill its place. Suppose I proved that all utilities equaled zero.
I know that Your-Moral-Philosophy is as true and undisprovable as 2 + 2 = 4. But still, I ask that you do your best to perform the thought experiment, and concretely envision the possibilities even if they seem painful, or pointless, or logically incapable of any good reply.
Would you still tip cabdrivers? Would you cheat on your Significant Other? If a child lay fainted on the train tracks, would you still drag them off?
Would you still eat the same kinds of foods—or would you only eat the cheapest food, since there's no reason you should have fun—or would you eat very expensive food, since there's no reason you should save money for tomorrow?
Would you wear black and write gloomy poetry and denounce all altruists as fools? But there's no reason you should do that—it's just a cached thought.
Would you stay in bed because there was no reason to get up? What about when you finally got hungry and stumbled into the kitchen—what would you do after you were done eating?
Would you go on reading Overcoming Bias, and if not, what would you read instead? Would you still try to be rational, and if not, what would you think instead?
Close your eyes, take as long as necessary to answer:
What would you do, if nothing were right?
It depends on how you disproved my morality.
As far as I can tell, my morality consists of an urge to care about others channeled through a systematization of how to help people most effectively. Someone could easily disprove specifics of the systematization by proving something like that giving charity to the poor only encourages their dependence and increases poverty. If you disproved it that way, I would accept your correction and channel my urge to care differently.
But I don't think you could disprove the urge to care itself, since it's an urge and doesn't have a truth-value.
The only thing you could do would be what someone else here suggested - prove that all other humans are NPCs without real qualia. In that case, I'd probably act selfishly when I felt like it, unless it caused too much psychological trouble to be worth it.