One trap that we must be wary of is adopting beliefs because they are popular among people who strive to think critically or scientifically, as opposed to being the result of critical or scientific thinking. One good example of this is RationalWiki which purports to report the political beliefs which all Rational(TM) people should hold. Similarly, I believe that most people who believe in materialism do so on the basis of extremely poor reasons and without knowledge of some of the stronger arguments for qualia existing. Maybe we should ultimately support materialism, but I get the impression that many people jump to this conclusion too quickly. Here are some points I believe people should consider first
(I know someone else in the rationality community wrote a post arguing for consciousness recently and I was meaning to read it, but I lost the link before I had a chance)
Failure to bite the bullet argument
If qualia don't exist, why is anything that you experience good or bad? In this case, things like pleasure, pain and meaning are nothing more than ways that particles can combine. But if this is the case, why are these combinations special or more important than other combinations? Why should we try to make certain combinations happen and certain combinations not?
It's fairly common to deny the existence of the objectively good or bad, but denying the existence of the subjectively good or bad is a much stronger claim. But everyone acts like this matters and so it appears somewhat hypocritical. And there is an argument that we should continue to act normally on the basis of meta-theoretic uncertainty, but no-one makes that argument.
Pascal's Wager Argument
This last point is actually a pretty strong argument for believing in qualia. If they don't exist, nothing matters, but if they do exist then we benefit from acting as though they do exist. Therefore, we should assume the later.
Expected Evidence Argument
Claiming the existence of qualia is often seen as anti-scientific, some people would even go as far to say that they don't see much difference between claiming the existence of ghosts or qualia. One key difference is that if ghosts existed we would expect objective evidence of them, even if the experiments would be hard to run. For example, we would expect a greater rate of howling in houses where someone was murdered. Even if they could only interact with us psychically, we would expect a higher rate of mental illness in these houses, even if the person living there had no idea of the past. Since if ghosts existed we would expect the existence of objective evidence, the lack of any such evidence counts against them.
On the other hand, it's not so clear that we should expect any objective evidence of subjective experience. Arguably, the only evidence we should expect of subjective experience is direct, subjective evidence. So the absence of objective evidence provides no Bayesian evidence against the existence of qualia.
Initial Foundations Argument
How should we come to understand the world? It seems like we might want to first pick a class of phenomena to be the foundation and that this should be whatever we are most certain of existing. We will then need to decide on the best way of knowing about that phenomenon and then choose a way of figuring out what other kinds of things might exist in the universe.
So what should our initial foundations be? One option is the external physical world, while the other is subjective experience. The later makes more sense to me as it describes why we believe in an external world. It isn't that we just assume it a priori, but instead that we notice patterns in our subjective experience and then theorise that there might be some object that exists independently of our experience causing these regularities. On the other hand, subjective experience makes much more sense to assume a priori and hence more sense as an initial foundation. Indeed, we could even say that this approach is truer to the scientific method since we even subject our belief in the existence of the external world to an empirical test. In other words, objective experience needs to be justified in terms of subjective experience and not the other way round.
Arguably the nature of an atom (or whatever elementary particle we choose) transcends its mere mathematical description. Firstly, the claim that "THIS IS ALL THAT THERE IS TO IT" seems like a strong claim and one which we can never know for certain. Surely, it is much more reasonable to maintain that there is at least the possibility of there being something in its nature beyond this. Indeed, if there were not, this would seem to imply that a perfect simulation of an atom is an atom and this seems absurd.
Following this reason, why can't there be an element of consciousness that transcends its mere mathematical description? And if a simulation of an atom is not automatically an atom, then perhaps a simulation of consciousness isn't automatically conscious?
Let's suppose I have a system with a variable x which takes values between 0 and 10. Suppose we define a second variable y which is also between 0 and 10 which satisfies x+y=10.
Is this a different system than the original? It seems this comes down to whether y is a new entity or just a relabelling of x. The one thing that I would expect to be uncontroversial here is that it is possible for this new system to just be a relabelling. Whether or not it is necessarily just a relabelling would be much more contentious.
If we were to say that sometimes introducing a variable that like that could be more than just a relabelling, then that would be to accept that objects can have a nature that is not fully encapsulated by their mathematical definition as I previously argued.
On the other hand, if circumstances like this are always just a relabelling, then there is no difference between the system with y in it and the system without y in it. This becomes important when y is a much more complicated property, such as the amount of "pain" an organism is experiencing. If the system is the same with the entity representing pain or without this entity, then it seems like it can't have been important. This implies that someone insisting it was just a relabelling must then bite the bullet of qualia being unimportant.
I'll quote Consciousness Comes First:
The issue is that physical properties are by their nature relational, dispositional properties. That is, they describe the way that something is related to other things and/or has the disposition to affect or be affected by those other things.
... However, if all we ever have is relational/dispositional properties—that is, if everything is only defined in terms of other things—then, ultimately, we have defined nothing at all.
It’s as though someone created a very elaborate spreadsheet and carefully defined how the values in every cell would be related to the values in all of the other cells. However, if no one enters a definite value for at least one of these cells, then none of the cells will have values.
In the same way, if the universe is to actually exist, its properties can’t be exclusively relational/dispositional. Something in the universe has to have some kind of quality in and of itself to give all the other relational/dispositional properties any meaning. Something has to get the ball rolling.
This argument is very similar to the transcendence argument and the relabelling argument in that it asserts things can be more than their mathematical descriptions, but still different enough that I felt it was worthwhile including separately. Interestingly the article argues the consciousness and conscious observations are what actually get the ball rolling, although I haven't thought this through enough to have a strong position yet.
Against the Illusion Argument
Some people say consciousness or qualia are just illusions. At best, this seems like a really bad analogy. For example, if I think I see an oasis, but it is actually an illusion, then it is the oasis that is illusionary and not my experience of seeing. In other words, if an experience is an illusion, then we still have the experience of seeing that illusion. And any discussion of illusions where the illusion isn't experienced seems to be a very misleading way of using that term.
Arguments against consciousness
I'll finish by noting that there are some very strong arguments against consciousness too. For quite a while I felt that the epiphenomenal theory was the most plausible, but there are two devastating critiques. The first is the evolutionary argument, it seems absurd that positive qualia would line up with events that are evolutionary advantageous and negative qualia would line up with events that are evolutionary disadvantageous if qualia has no causal mechanism to impact evolution. And the second is that it sure looks like qualia has a causal impact, since we are discussing them right now. So to believe in the epiphenomenal theory is to believe qualia for a reason completely independent from us actually having qualia.
These are very strong arguments, but I nonetheless worry about closing the door on this debate too quickly as there are quite possibly theories that we haven't considered yet, especially when there appear to be very strong arguments for qualia as well.