Three men want to climb a hill to get out of some fog.

Mr Religion sits down, shuts his eyes, and imagines sunlit vistas.

Mr Model-Agnostic takes a step, turns randomly, takes a step.

Mr Science makes two rules for himself: he must not step downwards, and he must not stay put. He also makes a guideline: he should not normally step sideways unless the way upward is blocked.

Mr Science succeeds in getting a ways up the hill and he calls down "I haven't seen any gods up here yet, and I don't think there are any". Mr Religion, with his eyes shut, says "I see them just fine". Mr Model-Agnostic says "what do you mean by 'up here'?"

Thanks Julian Morrison (from reddit).
Shared for the humor. In my version the Model Agnostic would learn from the scientist but go beyond his limits. For instance the scientist might not reach the top depending on the shape of the mountain with those rules ;p