On dualism

My approach to interpretation of QM assumes that the mathematically describable aspects of the world are ultimately responsible for why some conscious observations are more commonly experienced than others. I'll call that "reductionism". Many philosophers don't share that view, and here, I will consider the alternative viewpoint, which is generally known as "dualism" as it usually posits that "mind" (consciousness, qualia) and "body" (the aspects of the physical world which can be described mathematically) are two very different things with no logically necessary connection between them.

Both views have counter-intuitive implications, which is one reason that no consensus has been reached on the issue in philosophical circles. The other reason is that no consensus is ever reached on any philosophical question :)

The counter-intuitive implication of reductionism is that qualia - the way the colors appear to us, for example - either 1) are caused by mathematical properties, or 2) don't actually exist (known as eliminativism).

The problem with 1) is that our perceptions of color, for example, seem to have a "qualitative" aspect (e.g. red, green, blue) that doesn't seem like the sort of thing that mathematics could explain. There is an "explanatory gap" between them. The philosopher David Chalmers famously called the problem of understanding how math could explain things like qualia the "hard problem" of consciousness.

The idea 2) that qualia don't actually exist may seem absurd on the face of it, but upon closer inspection, it's a viable possibility. We think that qualia exist because our brains tell us that they do, but our brains are often wrong about what they are experiencing. This could make sense if the brain is composed of several parts or modules. The part of the brain that decides what it's experiencing need not be the same part that is undergoing the experience in question, if any. Thus, it could decide wrongly. This argument is related to my partial brain thought experiment.

Given these issues, it's not surprising that people find reductionism implausible. The alternative hypothesis is dualism: that qualia really do exist, but not due to mathematically describable properties. This avoids the problem of how math could cause the way that colors look, as well as the difficulty of believing that our brains are wrong about what they experience.

It's hard to understand what minds could be if they are not mathematically describable. Dualism introduces the question "What is mind?" which seems to me is as hard a problem as "How could qualia be mathematically caused?"

The other problem with dualism is that it doesn't explain why our brains tell us we have qualia. Telling us is a physical action, mathematically describable as processes in the brain, and it has ordinary physical consequences such as me typing this sentence. The brain's actions are determined by mathematically describable physics: electrical signals, chemicals, etc. So dualist qualia are epiphenomenal; they can't be what causes our brains to tell us we have qualia.

So if dualism is true, then there are two things going on at the same time: We have qualia, and unrelated to that, for some other reason our brains tell us that we have qualia. A dualist could argue that while that seems counter-intuitive, there is at least no problem in principle as there would be in trying to connect qualia to a mathematical explanation. However, the same is true for eliminativism, and that has the advantage of being less complicated.

If dualism were true, we might expect that some explanation of the "coincidence" between our qualia and the brain's belief in its own qualia must be rooted in anthropic selection; e.g. that there are many sets of laws linking minds to physics and that cases in which the "coincidence" doesn't hold see usually see just a random jumble. It seems unlikely to me that such an explanation would work, but I won't say that for sure. Partially it makes sense: By hitching its wagon to the mathematically describable functions of a brain, a dualist law connecting minds to physics would be more likely to produce a complex but coherent set of qualia. However, there is leeway. For example, if what the brain thinks it enjoys gave rise to pain qualia, and what the brain thinks it dislikes gave rise to pleasure qualia, would that not be anthropically valid? Another problem is that all of those laws (some of which wouldn't respect the Born Rule) could give rise to partially coherent "Boltzman brains" that outnumber normal observers.

Intuitively, we would want an explanation in which we do have qualia and they are responsible for why our brains think we have them. There is a version of dualism, called interactionism, in which that would happen - but it requires that our brains' thoughts and behavior are not based on the mathematically describable physical world, and that is highly implausible given what we know about both brains and physics. There is another major problem with it: Even a mental world could be divided up into pure experience qualia versus mathematically describable interactions; thus, interactionism reduces to epiphenomenal dualism, just with some of the mathematically describable action hidden away from the world described by known physics.

This should not be confused with 'quantum approaches to consciousness', which while also implausible, assume that the brains' behavior is due to their ability to collapse the wavefunction - which, even if it could occur, would just be another mathematically describable physical process. Likewise, even if psychic abilities existed, they would have mathematically describable causes and effects.

In general, ANY type of physical behavior can be described mathematically.

"Mental monism" aka "idealism" is the view that only minds exist; i.e. the physical world is sort of like a shared dream. This avoids the problem of linking minds to physics, but still would need to explain physics, with all of its mathematical behavior. It's hard to see how it could avoid introducing some mathematically describable things to help it along, and thus just become dualism.

In any case, supposing that dualism is true, what would it imply for interpretation of QM?

First, there would have to be a new law of nature linking the mathematically describable physics to mental properties. This would revive the possibility of single-world hidden variables, because unlike reductive computationalism, there is no logical reason that the new law couldn't just take the hidden variables into account. However, while that would be logically possible, it wouldn't be the simplest possibility, which is that the wavefunction (which must exist anyway) is what is taken into account. So based on Occam's Razor, we'd still have reason to believe in some kind of many-worlds interpretation. This kind of argument has been made by David Chalmers, who also argues that computationalism would still hold, and Don Page has made a proposal for this kind of dualist MWI.

The explanation for Born's Rule would probably be different with dualism that with reductionism, though. While it's possible that (as Chalmers argues) computationalism would still hold, and that Born's rule would follow from counting implementations, a more direct explanation becomes available: The dualist law could simply mandate that measure is proportional to the squared amplitude of the wavefunction, just as it does in Page's model.

There are few limits that we can place on what such a law of nature could be like - if it does exist, that is. It's not something we could investigate or deduce by logic. That is one reason that my investigations focus on the more restricted possibilities given by reductionism/eliminativism; the other is that I find it more plausible.