Non-reductive materialism (or materialism) is considered a from of monism, in the sense that ontologically everything is considered to be made of physical substances. It is non-reductive only in that it holds that some properties can never be explained in terms of lower level physical properties, even if they pretain to material objects. A non reductive materialist holds for example that mental properties, even though themselves physical, can never be explained in terms of neural states. Another example of non-reductive materialism would be our inability to explain biological causes in purely physical and chemical terms. I've seen this position also described as naturalism (in the context of John Searle's theory of mind).

More recently, there was this paper on the undecidability of certain quantum hamiltonians, challenging the reducibility of the macroscopic to the microscopic.

My question is: does this really count as monism? Isn't it for all practical purposes dualism?

I've seen Kant described as a dualist because of his noumenon/phenomenon dichotomy. But then based on the same logic, isn't dividing the world to ontologically identical, yet logically non-reducible, and therefore epistemically independent realms, amount to a form of dualism?

  • I'm curious to see what answers people have. My gut instinct is that the concept of Gestalt may shine a light on the difference. The behavior of the whole is derived from the state of its parts, but any attempt to explain the behavior from the parts alone falls flat. The whole is needed to explain the behavior, denying reduction.
    – Cort Ammon
    Dec 29, 2015 at 6:46
  • From a modeling/simulation perspective I would say there is no difference - the claim is that additional variables/dimensions are required in order to correctly model reality. This matches what dualism requires, though they may be defined by some in a way that would not allow them to be equated. I'm curious to see a more philosophic response than I can give.
    – LightCC
    Dec 29, 2015 at 6:52
  • see this paper by Jaegwon Kim.
    – R. Neville
    Dec 30, 2015 at 5:57
  • I think that the proliferation of words and concepts detracts from stating the obvious. Feeling my own pain is different from describing that pain in observational terms. Seeing a person flinch and hearing them say ouch are very different from the what happens when I get pricked with a needle. We infer the pain of others by analogizing to our own. All this theoretical gobbledygook may provide opportunities to publish papers in scholarly journals but only obscures the obvious. Jul 11, 2022 at 12:29

4 Answers 4


"Monism" is kind of an umbrella term, but maybe I can instantiate the idea pf non-reductive materialism in one argument. Henceforth, i will be referring to "monism" of the mind (as opposed to cartesian dualism.)

Donald davidson provides a atrong case for what he calls "anomolous monism." He accepts three premises:

  1. the interaction principle: There is a causal relationship between physical events and somemental states

  2. cause-law principle: a causal relationship entails a strict law governing thr relating each object

  3. anomalism principle: there are no laws that can predict mental states (explanatory non-reduction.)

Davidson then delineates between causation and explanation, saying that language utilized for this causal relationship is essentially physical. Since there isnt any strict law of the form p -->m, there must be somehing else going on. He then deduces that "m" must be token identical to a physical event. However this only describes the event, failing to explain it.

Here, metaphysical reduction (monism) actually hinges on explanatory non-reduction.

One can see how this argument can be extended to other physical phenomena, although i dont know if davidson would actuall stand behind this extension. However, this is an example of non-reductive materialism.


Non-reductive materialism is simply a combindation of substance monism and property dualism. There are two highest types of property, physical and mental (property dualism), inhering in one and the same type of substance, material (substance monism).

Monisms (1), dualisms (2), nihilisms (0) and pluralisms (3+) generally have the unit that they count in their name. Property -isms count highest types of properties, substance -isms count types of substances, existence -isms count concrete object tokens, and so on. You can be a property dualist, substance monist and existence pluralist at the same time. Those -isms are all relativized to what they count.


"Non-reductive materialism" is in many ways identical to "property dualism": both positions seek to have things both ways, to enjoy a monist ontology without paying any epistemological cost. But it is hard to see how a metaphysical assertion is significant at all if it carries no epistemological commitments, just as it is hard to see how an epistemological assertion can be defended in the absence of any metaphysical commitment. (Thus one may ask the Pragmatist, "Yes, but WHY is your belief utile?")


Property dualism is a type of reductive materialism which accepts the existence of most mental states such as pain, touch, believe, desire, etc and claims mental state can be totally reduced to its corresponding neurobiological process. It essentially treats mental states as one informational aspect of a two-face coin with its another aspect as the corresponding material process.

On the contrary, non-reductive materialism such as eliminative materialism rejects the existence of most mental states and claims most mental state is nothing but an epiphenomenon of the underlying neurobiological process such as the sound from a working engine. The sound cannot be reduced to the engine entirely since if no surrounding air, there won't be any sound from the same working engine now located on the moon...

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