That's what happens with decision-making under uncertainty: you aren't sure of something, yet you have to lawfully choose your actions. You don't choose your actions based on what you know is certain, you choose your actions depending on the specific state of uncertainty you're in. If you saw that X happened 100 times, you choose action P, and if you say Y happen 100 times, you choose action Q, even though your state of uncertainty permits the future to go identically in both cases, so that choosing different actions won't do any good. And maybe even the possibilities open for the future are exactly the same, but the fact that the past was different weights on the decisions just as well. That is what we are, cogs in the engine of possibilities, determining what happens even if we don't know what it is.