Qualia--the "what it's like features" of minds--pose a great challenge to a materialist view of the world. The two strongest and most popular objections to materialism based on qualia are the Zombie Argument and the Knowledge Argument. The current dissertation defends materialism against these two popular arguments. ;I argue that if zombie worlds exist, then qualia cause no physical events--they're epiphenomenal$\sb{\rm p},$ or epiphenomenal with respect to the physical domain of our world. I argue, however, that there is good reason (...) to reject the view that qualia are epiphenomenal$\sb{\rm p},$ and thus that there is good reason to deny the existence of zombie worlds. In turn, I argue that the Knowledge Argument likewise requires the existence of zombie worlds, and thus that the Knowledge Argument should likewise be rejected. (shrink)