*David Deutsch* is a physicist and philosopher known for his work on quantum computation, the multiverse interpretation of quantum mechanics, and his books *The Fabric of Reality* and *The Beginning of Infinity*. His theories on optimism, progress, the nature of scientific explanation, and the potential for human knowledge to grow infinitely have influenced my thinking greatly. I think the application of his advances on Karl Popper's epistemology could transform what we know about spirituality, psychology, and the nature of experience, especially given how these domains are riddled with bad epistemology: [[There are many bad spiritual ideas that we should criticize]] and [[Psychology isn't a science]].