Metaphysics is sometimes said to be the study of three questions: Why does the world exist? What does it contain? What is the place of human beings in the world? We will address all three questions. We’ll start with the first question, of why the world exists, focusing on whether there could be such a thing as a scientific answer to this question. We’ll then move on to second question, of what the world contains. At a very high level of generality, one might say that the world contains matter, distributed throughout space, and changing over time. We’ll examine these three components of the world—space, time, and matter—in some detail. Then we’ll turn to the third question, the place of human beings in the world. Here we’ll focus the discussion around the idea that human beings are, in effect, lumps of matter running complex computer programs in their brains. This raises a number of issues that are usefully approached through the lens of artificial intelligence. First, we’ll look at the relation between a human being and its body. Can one survive without one’s body? Could one upload one’s mind onto a computer system and “live” online? Second, we’ll look at the metaphysics of free will and determinism. Could an algorithm ever count as making a “free” choice? If not, in what sense—if any—is a human being any different? Finally, we’ll look at the relation between appearance and reality. Can a “simulated reality” be counted as real, or is it just mere appearance? If the latter, in what sense is the world as represented by our ordinary senses of sight, smell, etc, any different?