This from a review in TLS: I'll provide comments upcoming

REALITY+

Virtual worlds and the problems of philosophy
544pp. Allen Lane. £25.

David J. Chalmers

In Reality+ [Chalmers] turns from mind to matter, asking how we know what’s real. In 1641, René Descartes imagined himself deceived by an evil demon, the whole course of his experience a fraud. And then he tried to prove it wasn’t so. Chalmers gives Descartes’s predicament a technological spin. According to the “simulation hypothesis”, we are the inhabitants of an immersive, interactive, computer-generated space – a virtual or simulated world, not unlike the one depicted in The Matrix (1999). Chalmers makes three radical claims about such worlds. First: it’s impossible for us to know that we’re not in one; we could be living in a simulation now. Second: this wouldn’t stop the objects we encounter from being real. Even if our world is simulated, that simulation may contain real rocks, real trees and real people. Third: life in a simulation may be just as meaningful as life in a non-virtual world.

[Review by Kieran Setiya teaches philosophy at MIT; his new book, Life Is Hard, comes out in October]

RR