As I indicated in the Chalmers post last week, phenomenal consciousness has been on my mind lately. In the last few days, a couple of my fellow bloggers, Wyrd Smythe and James Cross, have joined in with their own posts. We’ve had a lot of interesting discussions. But it always comes back to the core issue.
Why or how do physical systems produce conscious experience, phenomenality, subjectivity? Why is it “like something” to be certain types of systems?
On this blog, when writing about the mind, I tend to focus on the scientific investigation of the brain. I continue to believe that the best insights to the questions above come from exploring how the brain processes sensory information and produces behavior.
For example, we got into a discussion on the Chalmers post about color perception and its relation to the different types of retinal cones, processing in the retinal layers, and processing in the brain. These dynamics don’t yet provide a full accounting of the experience of color, but it does provide insights.
But while these kinds of explorations do narrow the explanatory gap, and I think they’ll continue to narrow it, they’ll probably always fail to close it completely. The reason is that, the subjective never completely reduces to the objective, nor the objective to the subjective.
In the case of the subjective, we can only ever reduce phenomenal properties so far, say down to the individual quale or quality, like redness. These qualities are like a bit in computer software. A bit, a binary digit, is pretty much the minimal concept within the software realm, being either 1 or 0, true or false. No matter what the software does, it can’t reduce any further.
On the other hand, looking from the outside, a bit maps to a transistor (or equivalent hardware) which absolutely can be reduced further. Software can have a model of how a transistor works, but it can’t access the details of the transistors it is currently running on, at least not with standard hardware.
Similarly, once we’ve reduced experience to fundamental phenomenal properties, we can’t reduce any further, at least not subjectively, no matter how hard we introspect. But looking from the outside in, these phenomenal properties, these qualia, can be mapped to neural correlates, which can then be further reduced.
Of course, most phenomenal primitives are much more complicated than a bit, and will involve far more complex mechanisms. Some philosophers argue that we’ll never know why those complex correlates map to that particular subjective quality. But I think that gives up too quickly. The fact is that different experiences will have many overlapping neural correlates. The intersections and divergences can be analyzed for whatever functional commonalities they show or fail to show among phenomenal primitives, enabling us to get ever tighter correlations.
Something like this has already been happening for a long time, with neurologists mapping changes in patient capabilities and reports of experience to injuries in the brain, injuries eventually uncovered in postmortem examinations. Long before brain scans came along, neurologists were learning about the functions of brain regions in this manner. Increasingly higher resolutions of brain scans will continue to narrow these correlations.
But as people have pointed out to me, all we’ll then have are correlations. We won’t have causation. Which is true. Causation will always have to be inferred. However, that is not unique to this situation. In empirical observation, correlation is all we ever get. As David Hume pointed out, we never observe causation. Ever. All we ever observe is correlation. Causation is always a theory, always something we infer from observed correlations.
Nonetheless, the explanations we’re able to derive from these correlations will never feel viscerally right to many people. The problem is that our intuitive model of the mental is very different from our model of the brain. And unlike the rest of the body, we don’t have sensory neurons in the brain itself to help bridge the gap. So the intuitive gap will remain.
Similarly, in the case of the objective, we can never look at a system from the outside and access its subjective experience. The objective cannot be reduced to the subjective. As Thomas Nagel pointed out, we can never know what it’s like to be a bat. We can learn as much as we want about its nervous system, and infer what its experience might be like, but it will always be from the perspective of an outsider.
So the subjective / objective gap can’t be closed completely. But it can be clarified and bridged enough to form scientific theories.
But, some will say, none of this answers the “why”? Why does all this neural processing come with experience? Why doesn’t it just happen “in the dark”? Why aren’t we all philosophical zombies, beings physically identical to conscious ones, but with no experience?
I think the best way to answer this is to ask what it would actually mean to be such a zombie. Obviously when we say “in the dark” we don’t mean that it would be blind. But what do we mean exactly?
Such a system would still need to receive sensory information and integrate it into exteroceptive and interoceptive models. That activity would still have to trigger basic primal reactions. The models and reactions would have to be incorporated into action scenario simulations. And to mimic discussions of conscious experience, such as system would need some level of access to its models, reactions, and simulations.
In other words, if it didn’t have experience, it would need something very similar to it. We might call it pseudo-experience. But the question will be, what is the difference between experience and pseudo-experience?
The contents of experience appears to have physical causes and appear crucial to many capabilities. That makes it functional and adaptive in evolutionary terms. In the end, I think that’s the main why. We have experience because it’s adaptive.
But the intuitive gap will remain. Although like the intuitive gap between Earth and the planets, between humans and animals, or between life and chemistry, I think it will diminish as science makes steady progress in spite of it.
Unless of course, I’m missing something?