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> In my father's last months, I saw him medicated on morphine to the point of being near unconscious, and it's easy to imagine that he was having the same sort of weak experiences as I've had. None of this rattles my dualist intuitions at all.

But if your consciousness is separate from your physical brain, how come pumping certain chemicals affect consciousness on a very fundamental level ?

With your examples, you could explain those 'weak experiences' as some kind of signal-degradation between the incorporeal consciousness and the physical brain; but if you look at psychoactive drugs this explanation no longer flies.

I've taken psilocybin a few times and while there are sensory effects that you could explain as a transmission error it's a very tiny part of the experience. It really affects the way you think for a few hours, how can you explain that if consciousness is separate from the physical brain, why is it affected ?

Same goes for brain injury, people have complete changes in personality after suffering brain damage. How do you explain that if the brain is just a transceiver ?

Also, why do you trust your intuitions at all ? Intuition evolved to be able to deal with every day situations quickly. It breaks down when you start thinking about things outside human experience.

This is the (one of the) difference(s) between property and substance dualism.

You can claim that mental properties and physical properties interact without claiming that they are ontologically the same thing, or that one supervenes on (i.e. is just a result of the behaviour of) the other.

There are ways around the problem of interaction for substance dualists too, but they often rely on ad hoc interventions like God guaranteeing that the two worlds always match up (occasionalism).

> But if your consciousness is separate from your physical brain, how come pumping certain chemicals affect consciousness on a very fundamental level ?

I would argue that it doesn't.

Consider the following changes to your conscious experience:

- You stub your toe. Your experience changes to include pain.

- Someone says your mother's name. Your experience changes to include thoughts of your mother.

- You take LSD. Your experience changes to include a range of thoughts, sensations, and hallucinations characteristic of a psychedelic experience.

Which of these would you say count as a change to the part of you that we have been referring to with the word 'consciousness'?

I would argue that none of these are changes to what your consciousness is; your conscious experience continues to simply be the feeling of what it's like to have your own thoughts.

As your thoughts change, your experience of having them changes, but your consciousness never ceases to be anything other than the experience of having your thoughts. On a "fundamental level" nothing about consciousness has changed. Your consciousness is still sitting in a movie theater, watching your brain play out - it's just watching a different movie.

My argument rests on the view that your consciousness is not the haver of thoughts, but is the unexplained witness to the actual haver of thoughts - the brain.

As evidence for this I'd ask you to imagine what would happen if we built up, piece by piece, a perfect computer model of your mind.

It would have the same thoughts, it would express the same ideas, and we could look at the state of the computer at each moment and explain exactly which structures in your mind led to, for example, whatever you choose to say in response to this comment.

At no point would we find some sort of mysterious glitch in the computation, a glitch that we would have to assume was the point where the magic extra-physical force of consciousness entered the picture and exerted its control.

The mind and its thoughts must work without consciousness, as such consciousness can only be the experience of watching the mind do its work, and not an integral part of its functioning.

Modern, sophisticated dualists tend to think that consciousness just sits "on top" of brain activity, experiences are generated based on what's going on the brain. Many are "epiphenomenalists," who say that the content is determined only by brain activity, so the information flow is one way: brain -> conscious experience.

This has loads of problems (if consciousness has some influence over behavior, then what's the physical mechanism? And if there's none, then why are we able to even talk about it?). But dualists argue that materialism is even worse because it leaves you with outright paradoxes.

So, on this account, a weakly conscious system is just a system that's physically organized in a way that generates only weak experiences.

But is conciousness really an absolute quality like gravitation, or a qualitative one like say turbulence? Are you a turbulence dualist? If conciousness arises from certain physical arrangements and processes of matter at a macroscopic scale, like turbulence, then we can absolutely talk about it arising from non-concious matter just as we can talk about turbulence arising from static or ordered matter.

Dualists tend to have the intuition that it's an absolute quality--or at least, something with a special status beyond a higher-order description of patterns in physical activity. Your turbulence example is perfect: I can't imagine a fishtank that is atom-for-atom identical to a system that's experiencing turbulence, but somehow isn't "really" turbulent. I can easily imagine a system that is in the exact same state as my brain, but isn't having any internal experiences.

In Philosophy of Mind, this is discussed in terms of different types of "supervenience" and whether the mind supervenes on the physical world in the same way as something like turbulence or digestion, or in a more limited sense where the physical world determines the content of experience but there's still more going on; and I think some say it doesn't supervene in any sense at all (but that probably just comes down to a disagreement about terminology).

Physicalists say consciousness supervenes on physical processes in the exact same way as higher-order physical properties like turbulence, digestion, being alive, etc. Dualists feel that still leaves something out.

But if it's an absolute quality, it shouldn't depend on the arrangement or state of brain matter at all. The mass of a group of atoms is an absolute quality that doesn't change depending on how you move them about. Yet our experience of consciousness depends totally and critically in highly testable ways on the arrangement of atoms in our neurons. There doesn't seem to be much absolute about it at all. Even tiny changes can eliminate it completely. I just find it very hard to credit the absolute quality proposition, yet I don't see how dualism can avoid it.

So yes materialist answers to this question still have a lot of explaining to do, but dualism can't have a free ride either. It certainly doesn't seem to me to be simpler. At least in the physicalist explanation we can point to other epiphenomena and compare them to consciousness in broad ways. But what known, explicable, testable phenomena can we compare dualism to? It stands apart from all of science.

If you're interested in the philsiophical implications of being "semi conscious" check out section 3 of http://consc.net/papers/qualia.html