Can I know that I am not dreaming?

Question

Ask a Philosopher · Accepted Answer

Can I know that I am not dreaming? Well, I suppose the answer to this question depends on the definition of "knowing". Am I certain that I am not dreaming? No, I cannot be certain, as dreams can often feel quite real. However, I can be reasonably sure that I am not dreaming. For example, if I am able to interact with my environment in a meaningful way and make decisions that have tangible consequences, then I can be reasonably sure that I am not dreaming. Furthermore, if I am able to remember past events and anticipate future ones, then I can be reasonably sure that I am not dreaming. In short, while I cannot be absolutely certain that I am not dreaming, I can be reasonably sure that I am not. And that is good enough for me! Ha ha!"