 The second disagreement concerning the laws of nature may instead be a thorny issue. According to Lewis 1973, laws of nature are the true generalizations found in the deductive system that best describes our world (where “best” basically refers to the optimal trade-off between strength and simplicity; see the entry on  laws of nature  for an introduction to, and further details on, this debate): laws of nature supervene on the four-dimensional arrangement of particulars and their properties. To the contrary, the standard description of a CA does not take the space-time evolution for granted: it takes the automaton’s initial conditions as given, and generates the system evolution over time via the CA transition function. Particulars depend on laws, not vice versa. A CA world is not laid out in advance, but it grows as long as the laws are applied to particulars (a similar point is also made in Wolfram 2002: 484–486).