I think there's a fundamental flaw in your logic there. If I put tarantula behind your sofa, then we can say the probability of there being a tarantula behind

I think there's a fundamental flaw in your logic there. If I put tarantula behind your sofa, then we can say the probability of there being a tarantula behind your sofa is pretty much 1. If you have 5 sofas in your house, then the probability of there being a tarantula behind a random sofa in your house is 1/5. However, it doesn't follow that the probability of finding a tarantula behind any sofa is 1/5. All we can say about that is that it's non-zero.