What's Wrong with Moore's Argument?

Moore looked at his hands and argued: (1) Here are two hands. (2) If hands exist, then there is an external world. (3) So there is an external world.1 Something about this argument sounds funny. As we’ll see, though, it takes some care to identify exactly what Moore has done wrong. I will assume that Moore knows premise (2) to be true. One could inquire into how he knows it, and whether that knowledge can be defeated;