Abstract

T he term emergence is used to describe the appearance of new properties that arise when a system exceeds a certain level of size or complexity, properties that are absent from the constituents of the system. It is a concept often summed up by the phrase that “the whole is greater than the sum of its parts,” and it is a key notion in the burgeoning field of complexity science. Life is often cited as a classic example of an emergent phenomenon: no atoms of my body are living, yet I am living (see, for example, Morowitz [1]). Biological organisms depend on the processes of their constituent parts, yet they nevertheless exhibit a degree of autonomy from their parts (see, for example, Kauffman [2]). How can this be? These seem to be contradictory properties.