He is famous, or notorious, for having had a t-shirt printed with the slogan ‘Epistemology models Ontology’. However, the ontological indeterminacy of chaotic systems is very much open to question, given that the equations that model these systems are entirely deterministic (see God, Humanity and the Cosmos, pp133-35). Polkinghorne is well aware of this criticism, and has recently addressed it in Belief in God in an Age of Science (New Haven: Yale University Press, 1998) pp64-66. His point there is that the deterministic equations may in the end prove only to be approximations to the whole behaviour of such systems.