 The basic idea of emergence has to do with the fact that complex systems may display interesting novel properties—properties not possessed by their parts. This idea has been regimented in various ways. Following Chalmers, we can distinguish between weak and strong emergence. Weakly emergent phenomena are merely unexpected, given our knowledge of the domain from which they arise. Strongly emergent phenomena are not just unexpected; they cannot (not even in principle) be deduced from the domain from which they arise (see Chalmers 2006: 244).