Beliefs are quantitative, not qualitative. The more evidence you pile in favor of the claim, the stronger your confidence in it should be. Observing that there is no monkey is much stronger evidence than the geography based argument, and it’s probably enough, but the belief is not binary so having both arguments should result in higher probability assigned to it than with having just one argument, not matter how much stronger that single argument is. 3↑↑↑3+1>3↑↑↑3.
In practice, thing about it that way—what if the monkey heard you coming and managed to hide so well that you couldn’t find it even after looking? This is a very unlikely scenario, but still a possibility—and its less likely to happen in the Pacific Northwest than in, say, India. So the geographic argument reduces the probability of a hidden monkey scenario—even if only by a little bit—and thus increases the overall probability of having a monkelyless closet.
Beliefs are quantitative, not qualitative. The more evidence you pile in favor of the claim, the stronger your confidence in it should be. Observing that there is no monkey is much stronger evidence than the geography based argument, and it’s probably enough, but the belief is not binary so having both arguments should result in higher probability assigned to it than with having just one argument, not matter how much stronger that single argument is. 3↑↑↑3+1>3↑↑↑3.
In practice, thing about it that way—what if the monkey heard you coming and managed to hide so well that you couldn’t find it even after looking? This is a very unlikely scenario, but still a possibility—and its less likely to happen in the Pacific Northwest than in, say, India. So the geographic argument reduces the probability of a hidden monkey scenario—even if only by a little bit—and thus increases the overall probability of having a monkelyless closet.