by Eric Schwitzgebel
In 1% Skepticism, I suggest that it’s reasonable to have about a 1% credence that some radically skeptical scenario holds (e.g., this is a dream or we’re in a short-term sim), sometimes making decisions that we wouldn’t otherwise make based upon those small possibilities (e.g., deciding to try to fly, or choosing to read a book rather than weed when one is otherwise right on the cusp).
But what about extremely remote possibilities with extremely large payouts? Maybe it’s reasonable to have a one in 10^50 credence in the existence of a deity who would give me at least 10^50 lifetimes’ worth of pleasure if I decided to raise my arms above my head right now. One in 10^50 is a very low credence, after all! But given the huge payout, if I then straightforwardly apply the expected value calculus, such remote possibilities might generally drive my decision making. That doesn’t seem right!
I see three ways to insulate my decisions from such remote possibilities without having to zero out those possibilities.
First, symmetry:
My credences about extremely remote possibilities appear to be approximately symmetrical and canceling. In general, I’m not inclined to think that my prospects will be particularly better or worse due to their influence on extremely unlikely deities, considered as a group, if I raise my arms than if I do not. More specificially, I can imagine a variety of unlikely deities who punish and reward actions in complementary ways — one punishing what the other rewards and vice versa. (Similarly for other remote possibilities of huge benefit or suffering, e.g., happening to rise to an infinite Elysium if I step right rather than left.) This indifference among the specifics is partly guided by my general sense that extremely remote possibilities of this sort don’t greatly diminish or enhance the expected value of such actions. I see no reason not to be guided by that general sense — no argumentative pressure to take such asymmetries seriously in the way that there is some argumentative pressure to take dream doubt seriously.
Second, diminishing returns:

