What do you mean by “consciousness”? (part 2)
This is a variation on Frank Jackson’s thought experiment “Mary’s Room” (1982).
THE PARADOX OF MARY AND MARK
We start with this proposition: there is a difference between “knowing which things are red” and “knowing what red looks like”.
Suppose that Mary is blind from birth. Suppose she has some special equipment that allows her to navigate the world. In fact, the equipment is so good that she can do pretty much everything that sighted person could do. In particular, you can test her and she always knows which things are red.
But there is one thing she doesn’t know: she doesn’t know what red looks like.
Now consider Mark, who has normal eyesight. He “knows what red looks like”, because he has experienced red for himself.
This much of the argument should convince you that you believe subjective consciousness is real. There is nothing confusing or mysterious about the concept. You know exactly what I mean when I say “there is a difference between knowing which things are red and knowing what red looks like.”
When we test Mary or Mark, they give exactly the same answers, Mary using her equipment and Mark using his eyes. There is no detectable difference in their behavior.
This is the first corollary: you can’t detect subjective consciousness from the outside. Philosophers call this “the problem of other minds“.
Consider Mark’s eyes. According to mechanism*, his eyes are just machines. His visual cortex is just a machine. Even his “self”, the thing that has consciousness, is just an aspect of his brain, which is also a machine.
We said “Mary doesn’t know what red looks like, because she’s using this special equipment to figure it out.” But think about it: Mark is also using special equipment to know which things are red — his eyes and visual cortex. Mary and Mark are in exactly the same situation. Mechanism can’t explain the difference.
This is supposed to convince you that mechanism* can’t explain phenomenal consciousness.
This last is a form of the hard problem of consciousness. There appears to be a huge gulf between “experiencing something for yourself” and “finding out about something using a machine”. But we are machines, so how can there be a difference?
Solving the Hard Problem
Answers to the question posed in this thought experiment:
Substance Dualism: We aren’t just machines. There’s also another substance in us, a “spirit” or “metaphysical consciousness” that actually has the subjectivity.
This is no help, for two reasons. First, if there was some kind of “invisible stuff”, physics and neuroscience would probably have found evidence of it by now. Second, you’ve solved the hard problem but created a harder problem — now you have to explain why this “invisible stuff” feels something. Remember, it’s invisible, so … good luck with that.
Emergence: Mary and her equipment form a system that “knows what red looks like”, even if Mary herself doesn’t know what red looks like. The system has phenomenal consciousness of red, even if Mary does not.
Panpsychism: Machines actually do have experiences. It’s undetectable from the outside, but every machine, down to a single atom, actually has some subjective consciousness. Mary’s equipment knows what red looks like, the exact same way Mark’s eyes know what red looks like. All things know what their experiences feel like.
Eliminative materialism: There isn’t really a difference between “knowing what red looks like” and “knowing which things are red”. These are two ways of saying the same thing. The fact that it appears to be different to Mark is just a useful illusion— an artifact of his equipment, a distortion in his knowledge.
Biological Naturalism: Yes, they are both machines, yes they both implement the same function, but they implement the function using different machinery. Mark’s machine does different things to get the same result. One of the things it does differently causes Mark to feel something when he looks at red things. The technical details of how the machine is built matters, even if the information it processes and function it implements is the same.
Mysterianism: You can’t explain it. The paradox above proves there is no way to solve the problem using logic, language, or human minds.
None of these solutions are particularly satisfying, at least not to me. I feel like they all create even harder problems. Either A: non-human “stuff” or “systems of stuff” or “invisible stuff” have subjective experiences (which doesn’t really tell us what it actually is or how it works, and actually makes it harder to explain, not easier). Or B: subjective experience isn’t what it appears to be, so even our own experience doesn’t count as evidence for anything. Or C: Don’t ask. (Not helping.)
Subjectivity in General
Subjectivity is more than just identifying colors, of course. It includes all other kinds of sensory experience; the experience of our emotions; what it feels like to have thoughts, memories, imagination, “inner speech”, “train of thought” and other mental experience; the way it feels to do things on purpose (that is, use “free will” ).
It’s not hard to devise similar thought experiments for Mary and Mark that shows how the paradox works for most of these other things as well. Just suppose that, for some reason, Mary doesn’t have one of these things and uses machinery that serves the same function — machinery that is functionally equivalent.
There is far more to say about all of these (and probably others besides), but that’s getting a bit far outside the scope of this project. For now, I just need to convince you that you already know the difference between “subjective” perception and action and the equivalent objective functions.
| Objective (machines or programs) | Subjective (people) |
|---|---|
| Objective (machines or programs) | Subjective (people) |
| Know which things are red | Know what red looks like |
| Know what you should avoid | Be afraid |
| Know what’s damaged | Feel pain, suffer |
| Take an action based on a calculation | Doing something on purpose (have “free will”) |
| Cause an accident, due to malfunction or design flaw or misuse. | Do deliberate damage |
| Be dangerous | Be evil |
| Have a goal, a utility function, or an objective function. | Feel desire |
| Have a program trace of your computations. | Experience a “train of thought” |
| Communication between objects in your program. | Experience “inner speech” |
| Direct most of your computational resources at one problem. | Pay attention to something. |
| Model the features of your process inside your data (as a debugger or operating system can) | Experience what is happening inside your mind and know that you are experiencing it. (be “self-aware”) |
The Point
The things I hope you take away from this thought experiment are these:
- No Mystery to Subjectivity: You know what subjective consciousness is, and it’s an ordinary, obvious, day-to-day thing.
Or at least, you accept and act on its implications in your day-to-day life, regardless of what you might say when you’re caught up in a philosophical discussion of some kind.
- Problem of Other Minds: You can’t determine if something experiences subjectivity by examining their behavior.
This is one step (among several) to refuting the human essence assumption: these two “aspects of personhood” (subjectivity and human behavior) are not connected and don’t have to co-occur and thus they can’t stem from a common essence.
- The Paradox of Mary and Mark. Combining subjectivity and mechanism* leads to a paradox and this paradox is hard to solve.
No simple answer works for everyone all the time; it is profoundly arguable. If someone says the answer is simple or straightforward, they are most likely dodging the question.
- Subjectivity Matters. You have to recognize and appreciate subjectivity to lead a normal life.
I didn’t address this in this essay and it’s technically outside the scope of this project, but it’s crucial to appreciate that you can’t explain away subjectivity without paying an impossible price. Appreciating subjectivity is essential to living a normal life. (I will come back to this in a later essay).
People who try to explain away subjectivity remind me of Christine Ladd-Franklin, who wrote that she was a solipsist and was “surprised that there were no others”. Sometimes the things we say when talk about philosophy are not things that we actually believe and act on.
* I say “machines” and “mechanism” here, but the argument works exactly the same way if we want to focus on the system of information or the function that their brains/equipment are implementing. It doesn’t matter if we’re talking about the hardware of software; you will find the same paradox. So this thought experiment works equally well for the philosophical theories of functionalism or computationalism as it does for mechanism.
CHARLES GILLINGHAM 