In Reinventing the Sacred, biologist and complexity theorist Stuart Kauffman proposes an alternative to conventional supernatural religions. The basis for Kauffman's proposal seems to be complexity theory and the notion of emergence. In 2008, he wrote in New Scientist that "reinventing the sacred...will require a shift from reductionism...I do not believe that the evolution of the biosphere, economy and human culture are derivable from or reducible to physics. Physicists cannot deduce, simulate or confirm the detailed evolution of the biosphere that gave rise to the organised structure and processes that constitute, for example, your heart. Entities such as hearts, that have causal consequences, are 'real' in their own right."
Kauffman's entire world-view seems to be predicated on this anti-reductionism, yet it betrays a simple misunderstanding: it fails to understand the distinction between ontological reductionism and epistemological reductionism. Andrew Steane reviews Kauffman's book in the July issue of Physics World, and similarly fails to acknowledge the difference.
To digress, then: Ontology pertains to what actually exists and happens; epistemology pertains to what we know, or can know, about what exists and happens. Ontological reductionism merely proposes that the parts of a system, and the way in which those parts are organised and interact, uniquely determine the higher-level states and properties of the system. In particular, ontological reductionism proposes that what ultimately exists are the objects studied in physics, whether they be particles, strings, or whatever. Epistemological reductionism, in contrast, proposes that we can always explain and predict the higher-level states and properties of a system from the parts of the system. In particular, epistemological reductionism proposes that the theories and laws of any branch of science are derivable from those of physics.
Due to the conceptual incompatibilities between different theories, and simple limitations in the tractability of equations when dealing with systems containing billions of particles, epistemological reductionism is false. This is consistent, however, with the truth of ontological reductionism. Kauffman has spotted the falsity of epistemological reductionism (like many authors before him), but seems to think that this invalidates ontological reductionism as well, and bases his new concept of the sacred on this misunderstanding.
Consider, for example, one of Kauffman's central arguments:
"Weinberg rests his reductionism on the claim that the explanatory arrows always point downward, from society to cells to chemistry to physics. But with respect to evolution of hearts by natural selection, do the explanatory arrows actually point downward to string theory or whatever is down there? No. They point upward to the selective historical conditions in the actual evolution of organisms in the specific biosphere that gave rise to hearts...We have now moved beyond reductionism and arrived at emergence, both epistemological and ontological," (p43).
The fact that not all explanatory arrows point downwards, is a fact which mitigates against the possibility of epistemological reductionism, but it remains perfectly consistent with ontological reductionism. Kauffman proclaims that he has established the truth of ontological emergence, but fails to justify this claim. As Steane remarks, "the book implies that a case has been proven when it has not."