Monism, Dualism, and Pluralism

Monism suggests that there is only one sort of stuff -- typically physical stuff -- and every (contingent) entity in the world is made of stuff of that kind.

Dualism suggests that there are two sorts of stuff -- typically physical stuff and mental stuff -- and every (contingent) entity in the world is made of one or both kinds of stuff.

Trialism suggests on the other hand that there are three kinds of stuff.

Quadralism suggests that there are four kinds of stuff.

And so on.


In philosophy, the debate over which of these views is correct invariably centers on monism and dualism. Monists suggest that everything is physical (or mental) and dualists maintain that both sorts of stuff exist.

Is there a good reason to rule out trialism, quadralism, or any of the alternatives?


Dualism is generally motivated by the idea that consciousness cannot be the same sort of thing as the material objects around us. We know this only because of our first-person perspective on it. The nature of mental stuff (so the story goes) reveals itself to us to be different from physical stuff.

We don't have any reason to think that our subjective experience presents any other kinds of stuff to us, that cannot be reducible to physical stuff in the same way. Thus, we don't have the same reason to posit any more than two kinds of stuff. But this doesn't mean that we should rule out the possibility that there are more.

Here is an argument for thinking that there are other kinds of stuff. Our perspective on the mental stuff is quite fortuitous. Consciousness is not generally thought to ubiquitous in nature. It doesn't exist in rocks, or stars, or hurricanes. On the contrary, it appears to be limited to highly-organized collections of neurons. We are fortuitously positioned to recognize conscious stuff because they are closely with our bodies, and because they constitute a fundamental part of our own nature.

This raises the possibility: might there be a third sort of stuff, that is related to some other natural phenomenon the way that consciousness is related to brains? Might this stuff be produced by hurricanes, or galactic systems, or nuclear fussion?

At present, I don't think that we have any particular reason to believe in such stuff. But a zombie scientist who studied us would have no evidence for consciousness (apart, perhaps, from our testimony). The simple fact that we lack evidence isn't much of a reason to discount the possibility. We are like the zombie scientist with respect to other possible stuff produced by other natural systems.

So we have little reason to posit any particular third sort of stuff. Parsimony gives us some reason not to postulate any additional kind of stuff. But parsimony only provides us with weak reasons. If the only place that we have special epistemic access to does involve an additional kind of stuff, we shouldn't discount the possibility that other natural phenomena produce other non-physical and non-mental stuff.