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A tropical rainforest ontology: In search of a non-reductive naturalism

by John Halstead.

Cahoone describes a complex non-reductive view of nature which might better be called a “tropical rainforest ontology”

Cahoone describes a complex non-reductive view of nature which might better be called a “tropical rainforest ontology”

Analytical philosopher Bertrand Russell wrote in “A Free Man’s Worship” that the world which science presents to us is purposeless and void of meaning, and our lives are nothing but the “outcome of accidental collocations of atoms.”  Similarly, Steven Weinberg explains in his book on the Big Bang, The First Three Minutes: “The more the universe seems comprehensible, the more it also seems pointless.”  These are bleak visions of reality.  But is such a reductive materialism the only option for naturalistic Pagans?

Deserts and rainforests

Lawrence Cahoone, author of Orders of Nature (2013), draws on the work of philosopher William Wimsatt to create a systematic understanding of reality consistent with modern science that leaves room for the human mind and the experience of meaning.  Ontology is the philosophy of the nature of existence or reality.  Materialists favor minimalist ontology, one which is, in the words of philosopher, Daniel Dennett, “clean-shaven by Ockham’s razor”, or one that is, in the words of analytical philosopher, W.V.O. Quine, suited to those with an aesthetic “taste for desert landscapes”.  In contrast, Cahoone describes a complex non-reductive view of nature which might better be called a “tropical rainforest ontology” (Wimsatt), because it describes reality in terms of a plurality of properties, rather than just one — matter.  Cahoone’s non-reductive ontology is built on two premises: First, mind and matter are just two of many ontological properties of nature; neither is foundational, and neither may be reduced to the other.  Second, these ontological modes or properties are emergent properties of complex systems in the evolution of the universe.

Mind and matter

The history of metaphysics has been plagued by the question of the primacy of mind/spirit versus nature/matter, with the idealists taking one side and materialists taking the other.  Those who wanted to make room for religion have tended to privilege mind/spirit over nature/matter.  Philosophical idealism is an unsatisfactory solution for naturalists, while the alternative, a reductionist materialism is equally unappealing to many Pagans like myself.  Cahoone seeks to overcome this “bipolarism” of metaphysics.  He begins with the premise that nature is not equivalent to the physical or material.  Cahoone is a philosophical naturalist, in that he accepts that nature gives rise to mind and experience; but Cahoone is not materialist or a “physicalist”, because for him “nature” is not limited to the material.  For Cahoone, both mind and matter are just two of many properties of nature, and reality cannot be accounted for solely in terms of either.

Irreducibility and emergence

It was the hope of materialists at one time that all of nature could be accounted for in terms of physics.  Recent discoveries in neuroscience hold out the possibility of reducing the mind to the brain.  Similarly, Watson and Crick’s discovery of DNA seemed to promise that biology could be reduced to chemistry.  Likewise, it is hoped by some physicists that quantum mechanics could reduce all of it to physics.  In recent decades, however, thinkers in many different fields, including the philosophy of biology and the philosophy of chemistry, have called this project into question.  These thinkers challenge the notion that the laws of the smallest things in the universe can give a complete account of everything else.  They argue that there are phenomena in biology, chemistry, and solid state physics that cannot be deduced from the laws of subatomic physics.  These complex phenomena include chaotic systems, non-linear systems, self-organizing systems, and turning point phenomena.  When parts of a system interact in complex ways, then reductionist explanations fail.  In order to explain a complex system, we must refer to the system as a whole, whereupon it is discovered that the whole has properties which are not reducible to the parts.  These properties are called emergent properties.

Cahoone posits that ontology is itself emergent.  He argues there are levels of scale in nature.  In other words, a hierarchy of complexity is built into the universe.  The subatomic, solid-state physical, biological, psychological, and cultural exhibit a hierarchy of increasing complexity.  Each level has essential ontological distinctiveness.  That is to say, the physical, chemical, biological, mental, cultural are different ontological properties of nature.  While each level depends on the level “below” it, it cannot be reduced to that level.  The mental, for example, cannot exist without the biological, or the chemical or physical.  But the mental level manifests properties which do not exist on the biological, chemical, or physical scales, so it cannot be reduced to those levels.  According to Cahoone, this is why different scientific fields have developed for each level.  The ordering of the sciences in a hierarchical fashion is nothing new, and can be traced back at least to August Comte in the early 19th century.  Cahoone’s contribution is to apply this model to the ontological question of the nature of reality.

These levels of ontological complexity evolve over time and correspond to the evolution of nature from the simple to the complex.  About 14 billion years ago, shortly after the Big Bang, the only properties of the universe were those known today to sub-atomic physics.  After billions of years, heavier elements formed and hence the chemical complexity that would necessitate a science of chemistry.  After more billions of years, a planet formed with the ability to sustain life and the need for a science of biology.  Gradually, organisms developed the biological structures necessary to support mind and necessitate the sciences of psychology.  Culture — of which religion is a part — and the need for the sciences of sociology and history developed still later with the growth of human civilization.

Being “real”

In Cahoone’s view, societies are just as “real” as individual persons, and individual minds are just as “real” as physical brains.  Biological organism have the same ontological value as the molecules which constitute them, and molecules have the same ontological value as subatomic particles.  But all of these are a part of nature.  In this way, mind and culture can be understood from within nature, because nature is not merely the physical.  Mind is not a physical substance (i.e., the brain), but an emergent property of complex physical systems.  The same principle applies to language and culture, and possibly to religious or transpersonal experience.  While Cahoone discusses religion only briefly, this model seems to create a place for religious and transpersonal experience which avoids reductionism and instead might treat such experience as an emergent property of nature itself.

Cahoone is not the only thinker to conceive of nature in this way.  Critical realist Roy Bhaskar has reached similar conclusions in the context of the philosophy of the social sciences.  Alexandru Balaban and Douglas Klein have argued in the context of the philosophy of chemistry that the different scientific fields have emergent concepts that cannot be reduced to physics.  And cognitive scientist and critic of natural selection, Jerry Fodor, has argued that there is a hierarchy of explanatory levels in science and that the laws of a higher-level theory of psychology cannot be explained in terms of lower-level theories of the behavior of neurons and synapses.

But the most complete systematization of this theory that I have come across to date is the Tree of Knowledge (ToK) System created by psychologist Gregg Henriques.  The most novel aspect of the ToK is its visuo-spatial depiction of knowledge as consisting of four dimensions of complexity — Matter, Life, Mind, and Culture — that correspond to four classes of science, arranged along an evolutionary timeline.

It is interesting to speculate what might be the next dimension of nature to arise out of the complexity of human culture.

It is interesting to speculate what might be the next dimension of nature to arise out of the complexity of human culture.

This view gives human experience — including presumably religious and transpersonal experience — the same ontological value as matter, and all the other properties in the ontological rainforest, like quantum fields, linguistic signs, social action, and organisms.  In this view, religious experience would be judged, not in terms of whether it corresponds to some transcendental referent like God or spirit, but rather in terms of what it means for the ongoing evolution of nature that we are a part of.  Many naturalistic Pagans may find Cahoone’s “tropical rainforest ontology” and Heinriques’s Tree of Knowledge System appealing, as they offer a systematic understanding of reality that is faithful to our commitment to naturalistic causation, while not only leaving room for religious experience but placing it on par with matter as an emergent property of the universe.


Originally published at


Tree of Knowledge System website

Tree of Knowledge System expert article by Gregg Heinriques

Anderson, Phillip Warren, “More is Different”, Science, vol. 177 (1972) (.pdf link)

Cahoone, Lawrence, The Orders of Nature (2013)  [read an excerpt here (.pdf link)]

Cahoone, Lawrence, “Ordinal Pluralism as Metaphysics for Biology” in Beyond Mechanism: Putting Life Back Into Biology, ed. Henning, Brian, and Scarfe, Adam (2013)

Cahoon, Lawrence, “Toward a New Metaphysics of Natural Complexes” (2010) (.pdf link)

Clayton, Philip, and Davies, Paul, The Re-Emergence of Emergence (2006)

Collier, Andrew, “Critical Realism” [.pdf link] in The Politics of Method in the Human Sciences: Positivism and Its Epistemological Others, ed. Steinmetiz, George (2005)

Eronen, Markus, “Reduction in Philosophy of Mind: A Pluralistic Account” (2011) (.pdf link)

Henriques, Gregg, “A new vision for the field: Introduction to the second special issue on the unified theory, Journal of Clinical Psychology, vol. 61 (2005) (.pdf link)

Henriques, Gregg, and Cobb, H.C., “Introduction to the special issues on the unified theory”, Journal of Clinical Psychology, vol. 60 (2004) (.pdf link)

Henriques, Gregg, “The Tree of Knowledge System and the Theoretical Unification of Psychology”, Review of General Psychology, Vol. 7, No. 2 (2003)