Tuesday, 10 September 2013

Dualism is Not a Dirty Word

There are two major flavours of naturalism - methodological naturalism and metaphysical or philosophical naturalism. The former essentially means adopting the attitude that the latter is true as a pragmatic step without actually committing to the view that it is literally so. As such, only metaphysical naturalism is really in need of clarification.

I have already explained on this blog that I am a metaphysical naturalist, and what I think this entails, in particular the distinction between the supernatural and the natural. All too often these are unhelpfully defined simply as antonyms of each other.

To recap briefly on that earlier article, and I think to clarify and expand it in the light of recent thinking on the subject, I propose the following definition:
Naturalism is the view that the physical universe is fundamentally intelligible.
Let's extend this to make a number of other statements which I regard as equivalent or derivable from that basic definition.

(For the purposes of this discussion, a physical phenomenon or effect is an object, event or series of events which could in principle be objectively detected or verified by independent observers.)

In the naturalist view:
  • All physical effects have physical causes
  • All high-level physical phenomena can in principle be described in terms of lower-level physical phenomena
  • The most fundamental, basic level of physical phenomena corresponds to the fundamental laws of physics, which are expressible in terms of mathematics
In my view, this definition rules out libertarian free will, for example, because the decisions of people have physical effects yet libertarians reject any physical, deterministic account of human decision-making.

Most naturalists seem to be physicalists, believing only physical stuff such as matter and energy to exist, and many even think that physicalism is identical to naturalism. It isn't though, and this distrust of the non-physical is partly responsible for an unwarranted contempt for the alternative view - dualism.

When most people think of dualism, they think of Cartesian dualism, where some mysterious mind-stuff is supposed to account for human free will, conscious experience and intuition. In this view, we are more than mere biological machines, there is some spark of life, a spirit, that somehow interacts with the brain to give us our minds.

This spirit is not physical and cannot be reduced to physical laws. It is therefore supernatural by my definition. Naturalists quite rightly reject the idea of such a spirit, and so reject dualism.

But perhaps they are throwing the baby out with the bathwater, for there are other (and in my view correct) forms of dualism which are entirely compatible with naturalism.

Mathematical Platonism for example.

(The term "dualism" is usually used in philosophy to refer to views on the mind/body problem, so initially my bringing up mathematical objects may appear wrong-headed. Bear with me!)

Mathematical Platonism is the view that mathematical objects really exist, are not physical, and are independent of any mathematician or indeed any physical objects. I subscribe to mathematical Platonism for reasons alluded to in an earlier article, but I plan to expand upon that later.

For now, I will argue that whether it is true or not, it is compatible with naturalism because these mathematical objects have no direct causal powers in the domain of the physical - every physical event or object that can be explained in terms of mathematical objects can also be reduced to explanations according to the laws of physics.

So Fibonacci's numbers may give us a useful way to explain the pattern of spirals in a sunflower head (pictured at the top of this post), but whatever  the mathematical properties of Fibonacci's numbers that give rise to this pattern, the Fibonacci numbers themselves are not directly causing anything. The pattern of seed placement can also be understood as a result of entirely ordinary physical processes. The mathematical models we use to explain physical processes do not therefore cause the processes to happen, but instead provide useful ways to describe and model the high level outcomes of natural processes.

For many, this defeats the motivation for mathematical Platonism in the first place. Mathematical Platonism is viewed by some as a way to explain how we can perceive mathematical truth. For this to work as an explanation then it would have to be possible for mathematical objects to directly affect physical objects - mathematical concepts would need to be able to cause changes in our brains directly. This view of Platonism is inconsistent with naturalism and so I reject it.

For me, mathematical Platonism is more a way of thinking about things, and a way of resolving certain confusing puzzles. I remain a naturalist - everything that happens in the universe can be understood purely in terms of physics.

All well and good, but what's the point of this rant?

It is in the context of the eternal debates in philosophy of mind that these issues become important, and in particular when trying to explain phenomenal consciousness. On a previous post, I explained that my preferred response to John Searle's Chinese Room thought experiment was the Virtual Minds response. On explaining this to some naturalists, I am often told that it sounds "dangerously like dualism".

Well, it is dualism, but that should not rule it out. Any dualism that is compatible with naturalism (and this is such a dualism), ought to be considered on its own merits and not simply dismissed out of hand.

The instinct most people have that their conscious minds really exist is in my view at odds with the idea that only physical objects exist, because consciousness has no empirically detectable signifiers. Even if there were such a signifier, there is in principle no way we could know that this signifier proved or was required for consciousness.

Everything that a human mind can do could in principle be done by something like the Chinese Room or any other such computing device capable of passing the Turing Test. While I believe that any such device would be conscious, physicalists usually disagree since there is no way to test this and in any case all it is doing is shuffling bits around. Unfortunately, much the same is true for their own brains, so I don't think they have a leg to stand on.

In my view, phenomenal consciousness is empirically undetectable, and will remain empirically undetectable (at least directly), because it is not a physical phenomenon. Instead it is fundamentally subjective and so available only to the conscious entity.

But doesn't consciousness have causal powers? When we say we are conscious, this constitutes a physical event, and surely our consciousness must have a causal role in this.

Well, yes and no. Yes, in that we would not make such proclamations were we not conscious. No, in that everything we do can also in principle be explained in terms of physical events, just like the behaviour of a Turing Test passing machine as it proclaims it is conscious. In my view, our consciousness is what it feels like to be the sophisticated, self-aware mathematical structures that describe those physical processes. 

We are not physical, we are virtual minds existing on a physical substrate.

By analogy: I am the Fibonacci numbers; my brain is the sunflower.

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