Earley, Joseph E. "Ontologically Significant Aggregation: Process Structual Realism." Handbook of Whiteheadian Process Thought Vol. II. Edited by Michel Weber and Will Desmond. Heusenstamm, Germany: Ontos Verlag, 2008. 179-188.  

Abstract

Philosophical discussions of what sorts of things exist (ontology) now recognize that many types of entities that played important roles in the science of earlier historical periods in fact never existed. This raises the troubling suggestion that some (perhaps many) of the entities invoked by present-day scientists may also be figments of the imagination. In response to this suggestion, John Worrall (1989) has suggested that structural aspects of science persist even when ontological commitments change. He holds that the objects which scientists talk about do exist, but that they have unknowable natures. This position has been called "epistemological structural realism" (ESR) (Ladyman 2001). Others (French and Ladyman 2003) hold that objects scientists discuss do not exist, but, paradoxically, their structures do. This position has been called "ontic structural realism" (OSR). This view seems consistent (Earley 2006a) with Eddington's (1939, 147) manifesto: "What sort of thing is it that I know? The answer is structure. To be quite precise, it is structure of the kind defined and investigated by the mathematical theory of groups. Some scientists (including professor Stein and I) whose laboratory research deals with time-dependent phenomena find Whitehead's cosmological scheme to be a useful approach to ontological questions. However, complications arise in constructing an applicable process ontology. This paper outlines some of these challenges, and sketches a neo-Whiteheadian ontological scheme - here called process structural realism (PSR).