Did you account for the possibility you're dreaming, or in a simulation? Or in a simulation of a simulation and so on? Yes, that's the curse of real numbers. In

Did you account for the possibility you're dreaming, or in a simulation? Or in a simulation of a simulation and so on? Yes, that's the curse of real numbers. In practice you set a limit of precision required, and a threshold of evidence you need to tell you that the precision should be more precise. You can get quite far with Newtonian physics without considering the corrections of general relativity, you can get quite far in engineering by assuming linearity by only expanding the Taylor transform of a non-linear expression by a bit instead of infinitely, and you can do a lot by assuming probabilistic independence of your card counting from what's going on on Pluto right now.