Ontological naturalism is the view that only natural stuff exists (stuff that has some special connection to natural science). The term ‘naturalism’ refers to the methods of natural science in addition to the natural stuff that scientists are thought to study. A lot of philosophers say that they are ontological naturalists (of at least some type), but what exactly is such a view really about? Such a view seems to require that we can identify what’s natural and what’s not. And since philosophers don’t agree about what counts as natural, there are actually multiple types of ontological naturalism. I’m not convinced that such a distinction means much of anything, but I can sympathize with certain types of ontological naturalism more than others.
My definition of ontological naturalism is the following:
(1) The view that only natural stuff exists, which is thought to be identical to physical stuff. ‘Metaphysical naturalism’ is often taken to be a synonym with “physicalism.” Naturalists reject the existence of non-natural facts (perhaps mathematical facts) as well as supernatural facts (perhaps facts related to things like gods or ghosts). (2) Naturalism also often refers to various reductionistic identity theories, such as the view that some psychological facts exist, but that they are identical to nonpsychological physical facts (such as brain states). However, nonreductionistic views (of emergence) could also be considered to be types of naturalism. (3) The view that the only stuff that exists is stuff described by science. Not all philosophers agree that the reality described by science is merely physical reality.
Keep in mind that ontological naturalism should be differentiated from two different types of methodological naturalism:
- Epistemic naturalism – The view that the methods of natural science are the only way to know about the world.
- The view that scientists should only use hypotheses that refer to natural (rather than supernatural) things. For example, scientists shouldn’t hypothesize that lightning is caused by a god or spirit.
The appeal of ontological naturalism
I think there is a common sense appeal to ontological naturalism. I can sympathize with the view that nothing supernatural exists. I believe that everything people seem to think of as supernatural (such as ghosts, gods, miracles, magic, and psychic powers) are likely far-fetched, and the evidence for such things has been severely lacking. One type of ontological naturalism could simply state that nothing supernatural exists insofar as everything we think of as supernatural is far-fetched and we have no reason to think they are true. They are far-fetched insofar as there are reasons to think they are probably false given our understanding of the world. (Go here for more information about such extraordinary claims.)
The problem of ontological naturalism
The main problem with ontological naturalism that I will focus on is how we should distinguish natural from supernatural (or non-natural) things. It’s not clear how we can reliably make such a distinction or that being supernatural in and of itself is a reason to reject the existence of something.
What exactly is a natural thing? Consider the following answers to this question:
- Something is natural if and only if science has proven it to exist (or must assume it exists).
- Something is natural if and only if it is physical.
- Something is natural if and only if it isn’t supernatural.
Something is natural if and only if science has proven it to exist (or must assume it exists)
Let’s call this view scientific entities naturalism because the view is that the only entities that exist are entities that science proves to exist (or requires to exist for some other reason). If something is natural based on being the type of thing studied by scientists, then I see no reason why ghosts, gods, magic, miracles, or psychic powers couldn’t be natural. Such things can be studied by scientists. (For example, we could see is a person can move objects with her mind in controlled conditions.) If these things can be proven to exist by science, then scientific entities naturalism would tell us that they were natural all along. That is a far cry from the common sense type of naturalism I mentioned above.
Scientific entities naturalism seems to make it true by definition that anything that exists is automatically natural. In that case abstract entities and facts of logic might also be natural because science seems to require mathematical and logical facts (and this is pretty much Quine’s view). This view makes it trivial that nothing supernatural exists because it doesn’t help us know what should count as supernatural. It tells us that certain entities should be rejected insofar as they aren’t required for natural science, but we can’t just assume ghosts and gods aren’t assumed for natural science. We would have to have a good argument to show why ghost, gods, and any other supernatural entity aren’t required for natural science—and the reason a scientific entities naturalist rejects these things has nothing to do with them being supernatural. We should also reject the existence of any potentially so-called “natural” type of thing insofar as it’s not required for science. For example, bigfoot isn’t supernatural. It’s supposed to be a type of ape. But the type of ontological naturalism in question could give us a reason to reject the existence of bigfoot insofar as it (so far) seems to be unnecessary for science to posit their existence.
What exactly does scientific entities naturalism accomplish? The view would not necessarily tell us that gods, ghosts, etc. don’t exist. If they exist, then they are natural. The main thing it accomplishes is that it tells us to reject the existence of certain things (because we have reason to think science doesn’t require us to assume they exist). Is that a good reason to adopt this type of ontological naturalism? That is far from obvious. We need good arguments to think we should accept such a view. Perhaps one reason people embrace the view is simply to have a reason to reject the existence of certain things (like ghosts and gods). However, I think we can have a better reasons to reject the existence of those things. (I think they are far-fetched claims insofar as they seem unlikely to exist given my understanding of the world, and yet the evidence for such things tend to be too inconclusive for me to take seriously.)
A lot of people assume that science can’t possibly study ghosts, gods, etc. If nothing traditionally said to be supernatural could be studied by science, then we would be able to simply dismiss the existence of such things. We could know they don’t exist for free. However, I see no reason to agree with that. For example, we could actually find a way to talk to ghosts and hear what they have to say. That would be evidence that ghosts actually exist. Scientists have spent a lot of time and energy studying so-called supernatural things in the past, and they are often able to prove that nothing supernatural is going on. Such scientists are studying something supernatural and we could at least imagine that such scientists could actually find evidence of the supernatural. It is theoretically possible as far as I can tell.
Something is natural if and only if it is physical
Ontological naturalism is often taken to be synonymous with physicalism—The view that only physical things exist. However, then we still need to know what it means for something to be physical. Consider the following three ways we could define the physical:
1. Reductionistic physicalism – One view of physicalism is that everything that exists according to our best theories of physics (or perhaps a perfect theory of physics) is everything that exists. Nothing would exist except for the things studied by physicists. Of course, then we need to know what exactly physicists are supposed to study, how we should differentiate it from things like chemistry, etc. It’s utterly unclear to me how we can do all that.
Moreover, reductionistic physicalism seems to have similar problems as scientific entities naturalism. It says that only stuff needed for science are natural (and exist), but it says pretty much nothing about whether things like ghosts or gods exist (or should even be considered to be supernatural). However, it also seems like physicalists of this type pretty much always reject the existence of mathematical and logical facts because they are said to be nonphysical (or abstract). It is utterly unclear to me how they can define the physical in such a way to somehow rule out such facts. Perhaps most philosophers only say they are reductionist physicalists of this type after they somehow decide that mathematical and logical facts aren’t needed for physics. (Many philosophers are not convinced that they are right about that.)
What exactly does it accomplish to be a reductionistic physicalist? I don’t know how to answer that question at this point of time. I suppose it could just be a description of a series of conclusions some philosophers reach.
2. Nonreductionistic physicalism – Another view of physicalism is that everything physical is part of a causal chain. In that case animals, rocks, and minds could all be physical (part of a single causal chain). These things need not be reduced to other things. For example, chemistry might not be reducible to physics. Emergent things (that exist because of some state of affairs) can be greater than the sum of their parts, and such things can be physical. In that case the mind might be emergent, unique, and totally different from any other physical state.
Nonreductionistic physicalism also seems to suffer from problems similar to reductionistic physicalism. It’s not clear why physicalists of this type seem to think they have to reject mathematical and logical facts (which are often said to be abstract rather than physical). This view also fails to tell us what counts as supernatural, or that ghosts or gods are supernatural. Perhaps ghosts and gods are physical.
Once more, it’s not clear what nonreductionistic physicalism can accomplish other than merely describe certain conclusions a person agrees with.
3. Provisional physicalism – A third view of physicalism uses archtypical examples of physical things, such as photons, electrons, atoms, tables, and trees without giving a precise definition of the physical. Other things very similar to things in the list could also be said to be physical. It might be that the term ‘physical’ is a family resemblance notion without precise necessary and sufficient conditions. In that case we can generally give good examples of physical (and perhaps nonphysical) things without claiming that there’s a precise way to differentiate the two.
The reason that this type of physicalism is provisional is because someone could claim that the only things that exist are physical based on the fact that (so far) we only seem to have a good reason to believe that physical things exist. Of course, more would have to be said. We would have to argue for that view and explain why nonphysical things (like moral facts, logical facts, or abstract entities) should all be rejected. (I am personally skeptical that archetypical examples of nonphysical things (like mathematical facts don’t exist.)
I could imagine pragmatic physicalism to be useful insofar as it could inspire a type of methodological naturalism—scientists who decide that only physical things exist could decide that we (so far) have no reason to think nonphysical things exist, so we have a pragmatic reason to stop devoting resources to scientific research involving nonphysical things. (Perhaps part of the problem is that we have never made scientific progress when researching or hypothesizing about nonphysical things.)
Something is natural if and only if it isn’t supernatural
Instead of merely concentrating on defining the natural, we could try to define the supernatural. Perhaps that could give us insight into what we should consider to be natural. What is the supernatural? Consider the following definitions:
1. Laws of nature naturalism – One, we could say that something is supernatural if and only if it violates laws of nature. Miracles are paradigmatic cases of supernatural things and they are often taken to be violations of laws of nature. However, this view of the supernatural might not apply to ghosts and certain other paradigmatically supernatural entities. (Perhaps ghosts can’t interact with the physical world.)
One potential benefit of this view is that it would not automatically force us to say that abstract entities, facts of logic, or moral facts are supernatural. Such things might be either natural or non-natural because they don’t violate laws of nature. Many philosophers find it plausible that abstract entities, facts of logic, or moral facts can exist; so it seems premature to require people to reject their existence.
2. Realm naturalism – Another view of the supernatural is that supernatural things can cause things to happen in the physical realm, but that supernatural things are not constrained by the physical realm to the degree that physical things are. The mind (as understood by substance dualists) would be said to be supernatural in this sense because the mind is thought to be able to move the body, but the mind is thought to be causally unaffected by the body to some degree. Various conceptions of gods and ghosts also fit this definition. Again, abstract entities, facts of logic, and moral facts would not be considered to be supernatural given this definition.
3. Provisional naturalism – We can claim that the supernatural is not supposed to be precisely defined in terms of necessary and sufficient conditions, so we could give various paradigmatic examples of the supernatural. We can say that ghosts, gods, spirits, magic, miracles, and psychic powers are all supernatural. Other things that are very similar to these things could also be considered to be supernatural based on having a family resemblance.
This third definition is a provisional type of ontological naturalism insofar as it would say we (so far) have a reason to reject the existence of all supernatural things, but it doesn’t rule out the possibility of supernatural things being proven to exist at some point in the future. Perhaps we could provisionally decide that all paradigmatically supernatural things seem to be unlikely to exist with what we know about the world and decide to provisionally reject all other similar supernatural things until we have a good reason to think otherwise. We might also decide that scientific research (and hypotheses) about the supernatural have been unsuccessful in the past, and decide that it would be a good idea to stop funding research of the supernatural. This provisional type of ontological naturalism seems to be similar to the common sense type of naturalism that I mentioned above. Of course, we would have to argue further as to why we should think all supernatural things should be rejected. Are supernatural entities unlikely to exist considering what we know about the world? That is not entirely obvious, but it might be right.
Many types of ontological natural are highly contentious and controversial views, and all types of ontological naturalism require that we can explain why supernatural things are unlikely to exist. Each type of ontological naturalism describes the views of various people, and those people need not be close-minded to the possibility that supernatural things exist. Even so, the existence of supernatural entities would falsify ontological naturalism. (However, certain ontological naturalists would not say proving ghosts, gods, etc. to exist would falsify naturalism, because such things would then be said to be natural.)
I know of no good way to know how to precisely determine if something is natural, non-natural, or supernatural. Scientific entities naturalism says pretty much nothing about what counts as natural, so (according to that view) the claim that everything is natural means nothing other than that everything that exists can be proven to exist by science or must be assumed to exist by scientists. Reductionistic and nonreducionistic types of physicalism do seem to require some vague way of knowing if something is natural or supernatural, but it is not clear to me that such a distinction could be made in any clear-cut way.
Finally, it is not clear that being ontological naturalists can make a positive difference of any kind, and many types of ontological naturalism do seem to suffer from being a bit speculative. Even so, the provisional types of naturalism mentioned here could potentially make a practical difference insofar as they could motivate us to refuse to engage in (or fund) certain types of scientific research (that involve the supernatural).
- Do Extraordinary Claims Require Extraordinary Evidence?
- Stanford Encyclopedia of Philosophy: Naturalism
- Stanford Encyclopedia of Philosophy: Naturalism in Mathematics
- Stanford Encyclopedia of Philosophy: Physicalism
- How not to attack Intelligent Design Creationism: Philosophical misconceptions about Methodological Naturalism