Friday, February 08, 2019

Is a Blind Person's Consciousness Partly Contained in Her Cane?

Karina Vold spoke interestingly last week at UC Riverside on "vehicle externalism" about consciousness. (Here's some of her published work on the topic.) According to vehicle externalism, the "vehicle" of consciousness -- that is, its actual physical basis -- is not, as many think, the brain, but rather the brain plus some of the world beyond the body. Central to Vold's presentation was the classic example of the blind person and her cane.

Before discussing that example, I want to start (as Vold did) with a well-known argument fom Andy Clark and David Chalmers. Otto is a forgetful fellow, and so he always carries a notepad with him, full of reminders. When he wants to go to the museum, he pulls out his notebook, which reminds him that the museum is on 53rd Street, and then heads that way. Without the notebook, he would be lost. Clark and Chalmers argue that Otto's retrieving information from the notebook is not relevantly functionally different from a less forgetful person's retrieving the same information from memory. Because of this, they argue, it's correct to say that as long as the notebook is reliably in his pocket (even before he consults its contents), Otto knows that the museum is on 53rd Street. Otto's memory, and thus his mind, is not entirely confined within his skull. It extends to the notepad in his pocket.

Vold and some other defenders vehicle externalism (but not Clark and Chalmers) want to say something similar about consciousness. To explain how and why, Vold invokes a blind person with a cane -- let's call her Genesis [name randomly selected].

Genesis skillfully uses her cane to help her move about, swinging and tapping it to detect obstacles, objects, slopes, textures, and materials. A skilled cane user can learn a lot from a tap or two! Her cane is always with her when she walks, and in some sense it feels almost as if it were a part of her body. (You might experience a lesser version of this if you take a pen in your hand and use it to stroke and tap things. Many people report that it feels almost as though they are directly feeling objects via the pen, as opposed to feeling the pen in their fingers and inferring from those sensations what the objects beyond must be like.) Genesis experiences the world via a sensorimotor loop that travels from brain through arm and hand, through cane, then both into the ears and back up through the arm into the brain.

If a brain-based view of consciousness is correct, it is from her brain alone that Genesis's sensory experience arises, with signals up the arm serving only as input to the brain processes supporting consciousness. In contrast, according to vehicle externalism, the cane and arm do not merely provide inputs. Rather, consciousness arises from cane and arm and brain jointly operating as an integrated system. Consciousness does not depend only causally on the input Genesis receives from the stick. Rather the stick itself is a constituent of an extended system that as a whole constitutes or gives rise to consciousness.

The difference between the internalist input view and the vehicle externalist view can be a little hard to fathom. Here, I think the philosophical concept of supervenience can help. But before I get to supervenience, let me stave off one possible error. The vehicle externalist is not merely saying that consciousness feels as though it is located in the cane. Everyone agrees that consciousness can feel as though it's somewhere other than the location of the system that gives rise to the experience. Pain can feel as though it's in your toe even though the material process that directly gives rise to it, on an internalist view, is in the brain rather than the toe. This seems especially clear in the case of phantom limb pain.

A set of properties, properties of Type A, supervenes on another set of properties, properties of Type B, if and only if there is no possible difference in the As without a difference in the Bs. For example, the score of a baseball game supervenes on the number of times each individual player has officially crossed home plate. There is no possible difference in score without some difference in the number of times at least one individual player has crossed home. (The converse is not the case: It is possible for the score to be the same even if some individual runners had scored a different number of runs.)

The core question of vehicle externalism, as I see it, can be expressed in terms of supervenience: Does consciousness supervene on the brain, as the internalist would say? Or is it possible to have different conscious experiences despite having exactly the same brain states? (Not all vehicle externalists need actually be committed to denying the supervenience of consciousness on the brain, but then I worry that their view might collapse into a notational variant of the internalist input view.)

Consider Otto. If you accept vehicle externalism about Otto's memory, then it should be possible to change Otto's memory state without changing his brain state at all. Otto-1 has the notepad in his pocket. Otto-2 has been pickpocketed, though he hasn't noticed it. Assume that Otto-1 and Otto-2 have exactly the same brain states. On Clark and Chalmers's vehicle externalism, Otto-2 no longer remembers where the museum is (and many other things), although Otto-1 does remember. Despite this difference in memory, on Clark and Chalmers's internalist view about consciousness, Otto-1 and Otto-2 will differ not at all in their conscious experiences. Their conscious experiences will only start to diverge when Otto-2 reaches for his missing notebook. Otto's consciousness, but not his memory, supervenes on his brain state.

Now consider Genesis. If a substantive form of vehicle externalism about consciousness is correct, we should be able to concoct a case in which Genesis-1 and Genesis-2 have identical brain states but non-identical conscious experiences. To claim that such a case is possible is just what it is to deny that consciousness supervenes on the brain.

In other words, we want to imagine changing the cane in some important way, without changing the brain. The vehicle externalist ought to say that the conscious experiences will be different. If consciousness is literally partly contained in or constituted by the cane, Genesis-1 and Genesis-2, with identical brains but different canes, ought to have different conscious experiences.

Let's consider a small slice of time -- a third of a second -- when Genesis's cane is swinging through the air between things. Suppose, hypothetically, that a clever prankster were able to undetectably change the tip of the cane just before that third of a second. Genesis is swinging her cane and touches a passerby who "accidentally" jostles the cane a bit. In Genesis-1, the cane is unchanged after the jostling. In Genesis-2, the long tip of her cane has been covertly swapped for a shorter tip of the right weight (slightly heavier, to compensate for the difference in leverage). The swap is so perfect that for the entire third of a second after the bump and before her cane strikes the next object, the signals into their brains are identical. For this brief duration, Genesis-1 and Genesis-2 have identical brain states but different cane states.

Shortly, their brain states will diverge: Genesis-2 will think the next object is closer than it is, and after the strike she might notice some difference in the sound and tactile dynamics of her cane. The question concerns what happens before that next tap of the cane. The canes are different. The sensorimotor contingencies are different (though that difference has not yet resulted in divergent input signal). Will the conscious experiences, already, be different?

It seems unintuitive that they would be. Most of the vehicle externalists about consciousness I have pressed on this question either hesitate to answer, or try to wiggle out in some way. Also, if introspection is something that happens in the brain, and if consciousness is always immediately available for introspection, the case seems to present trouble. Some philosophers might think that if the view implies a not-immediately-introspectible difference in conscious experience, that would be a fatal flaw. But I disagree. Intuitions about consciousness aren't always correct, and simple, immediate-access models of introspection may not be correct. That Genesis-1 and Genesis-2 have different conscious experiences already in that first third of a second is an interesting possibility, worth considering, and it seems to flow naturally from vehicle externalism. If this is a "bullet", I think the vehicle externalist should bite it.

[image by Ken Walton]


Lee Roetcisoender said...

These arguments are indeed cleverly crafted and cute. But in spite of these clever anecdotal arguments, one must be compelled to consider the following. If consciousness is the linear continuous manifold which the discrete systems of appearances run on, then all of these arguments would correspond to that architecture. In short, both the cane, nervous system, brain, our own phenomenal self-model and every other phenomenon in our universe would be a discrete system that runs on the continuous platform of consciousness itself.

According to this model, consciousness would be universal, and if consciousness is universal, then consciousness would be fundamental in explaining the complex relationships which coalesce into the diversity and novelty of the discrete systems which make up the expression. This simple and parsimonious explanation would be a viable model which could then be utilized to replace the archaic model of the laws of nature, a model which is grounded in mysticism.

Unknown said...

Isn't externalism and internalism the same, even though a cane is artifical, a brain is natural and seem a subject of a interacting mind, interacting with a unremembered third unacknowledged being, a self...

Is dualism evolving to being presence...

Shelley said...

I don't have access to the Vold article to which you link. Maybe you would be so kind as to send it to me. In the meantime, would you please tell me if there are any works in the References by disabled people or disability studies scholars?


SelfAwarePatterns said...

The unintuitive nature of Genesis-1's consciousness being different than Genesis-2's can be somewhat ameliorated by considering a different scenario. Suppose both have a brain implant which conveys vision information directly into the pathways between their visual cortex and other brain centers, but Genesis-2's has been hacked to convey incorrect information similar to the cane scenario.

In this scenario, her organic brain state, during the time between the hack and her discovery her interface is compromised, are identical to Genesis-1's. However, her *expanded* brainstate is now different. This seems to get around the bandwidth issue that Clark and Chalmers identified.

If that still seems easy to dismiss, then consider identical clones Ingrid-1 and Ingrid-2, not carrying any notebooks or in need of any canes, at least not initially. Suddenly Ingrid-2 develops a lesion in her visual cortex that causes it to convey incorrect information similar to the above scenarios. The rest of her brainstate is identical to Ingrid-1's. Introspectively, Ingrid-2 hasn't noticed the issue yet. Consciousness identical or different?

We might then say the only thing that matters is their introspective state, but that's adopting a pretty narrow conception of consciousness. And what do we do if the brain interface enhances introspection?

All of which is to say, I'm not sure there's a fact of the matter here. All we have are views that may be more or less productive. In that sense, Clark and Chalmers may have a point about the bandwidth issue.

Eric Schwitzgebel said...

Thanks for the comments, folks!

Lee: Panpsychism, or some similar view, does seem to me to be among the possibilities.

Unknown: I agree that the distinction between "natural" and "artificial" can look arbitrary, especially concerning the grounds of consciousness.

Shelley: It was an oral presentation. I don't think it's circulating in written format, and I don't know about the references.

SelfAware: Interesting way of expanding the examples. I agree that that way of developing it can help make the case seem somewhat less unintuitive.

Shelley said...

I meant that references in the article to which you link. I got the impression from your remarks that Vold uses the example in the article too. I was wondering if blind or other disabled authors had been cited in any way.


Shelley said...

As I indicated to you in email, Eric, I think this use of a blind person is troubling. Such an incident amounts to abuse of a blind person.

Eric Schwitzgebel said...

Yes, Shelley, I see your point. I don't believe that Vold uses the cane example in her 2015 JCS article.

Eric Schwitzgebel said...

Also, Shelley, to be fair to Karina, she did not mention altering the cane.

James of Seattle said...

Just wanted to point out that if you think of consciousness as certain kinds of processes, there is no issue here. You simply designate a system (Genesis with cane, Genesis without cane, Genesis’ brainstem), and ask of the system what consciousness-type processes it is capable.


David Duffy said...

I think the artificial-natural and internal-external distinctions are not useful here. If I suddenly have a stroke causing a focal deficit, let's say a specific agnosia, I could be unaware of that deficit until it reveals itself in specific environments. Until then, my conscious experience will remain unchanged. Consciousness will only alter after (probably repeated) learning experiences lead to an alteration in self image.

And in the rubber hand perceptual experiments, "many people report that it feels almost as though they are directly feeling objects via the" hand. That is, consciousness immediately expands to include the extra hand.

Luke Roelofs said...

I'm wondering what exactly the thesis of active externalism is - that in principle, an external object could be part of the supervenience base of some being's consciousness (which is surely pretty hard to deny, and which your argument doesn't touch) or that this is sometimes the case for actual human beings? I can't directly access Vold's paper, but I get the impression she wants to defend something like a 'parity thesis': if we would think if of it as part of the base when it happened in the head, we should also think of it that way when it happens outside the head. But this principle seems less helpful with consciousness than with cognition, because we're so unsure what things to regard as part of the supervenience base for consciousness generally. Cognition's also hard, but I think a lot of people feel more confident in a pattern of functionalist-y intuitions for cognition than for consciousness.

(Also, I'm not sure panpsychism, if that's the kind of thing Lee is suggesting, does actually affect the question much. It guarantees that the external prop is part of the supervenience base for *some* consciousness, but still leaves open the question of whether any of that consciousness should be thought of as part of 'my' consciousness, where that's something like the consciousness referred to when I introspectively demonstrate 'all of this'. It does raise the possibility that this demonstration might not determine a single unique precise boundary, though, any more than pointing and saying 'that space over there' does. Still, for most purposes I'm inclined to think of myself as both a panpsychist and a vehicle-internalist?)

Luke Roelofs said...

(quick edit: when I said panpsychism makes the cane a supervenience base for *some* consciousness, I should probably have disjoined that with '...or makes it supervenient on *some* consciousness', to reflect more idealist versions. But the question of whether that consciousness is or is not part of 'this one here' still remains.)

Shelley said...

Eric, It was not unclear to me that you introduced the idea of tampering with the cane. Shelley

Lee Roetcisoender said...

"It guarantees that the external prop is part of the supervenience base for *some* consciousness, but still leaves open the question of whether any of that consciousness should be thought of as part of 'my' consciousness..."

If consciousness is seen as the hardware that the discrete systems (software) of appearance run on, then there is no such thing as "your" consciousness or "my" consciousness because there is no separation of consciousness itself, there is only one. The distinction would occur at the ontological level of individual experiences, the discrete experiences that are made possible and intricately linked through the linear, continuous manifold of consciousness itself. The intricately complex relationships which make up the diversity and novelty of our phenomenal realm are made possible through the linear, continuous manifold of consciousness, and those relationships do not occur in isolation.

A very important ontological distinction needs to be made when discussing consciousness. According to my models, consciousness may indeed be a feature or attribute of the ontological primitive, but it is not the underlying qualitative property as such. So I am not an idealist. The phenomenon of consciousness as an objective reality needs to be divorced from the experience of consciousness or else one is left with a model where the tail ends up wagging the dog.

Unknown said...

I'm not sure how far we may just be using the term 'consciousness' differently. But I think we can bypass that issue. You say 'there is no such thing as "your" consciousness or "my" consciousness because there is no separation of consciousness itself, there is only one. The distinction would occur at the ontological level of individual experiences...' Ok, but the distinction has to come somewhere. Whatever your ultimate metaphysics, you need there to be something that makes it true that 'Luke experiences pleasure when he eats olives but some people don't cheerful', etc. Whatever we call that distinction, it's the topic of the debate here about canes and brains.

Lee Roetcisoender said...

"Whatever your ultimate metaphysics, you need there to be something that makes it true that 'Luke experiences pleasure when he eats olives but some people don't cheerful', etc..."

Absolutely, the ontological distinction of Luke's experience of pleasure in contrast to someone else's experience of displeasure is determined by the structural, qualitative properties which underwrite the novelty of a given discrete system, along with the limited degree of self-determination that is also intrinsic to discrete systems. If canes, human limbs, nervous systems and brains are discrete systems running on the linear continuous manifold of consciousness, their relationships with each other are intrinsically linked through that manifold.

Eric Schwitzgebel said...

Thanks for the continuing comments, folks:

David: I think that might be a way of expressing what the vehicle externalist thinks. The conventionally recognized line between "internal" and "external" isn't especially important.

Luke: I do think that most vehicle externalists want to argue that it's not just the case that the supervenience base *could* extend, but also that it some actual cases it does extend.

Luke and Lee (/unknown): I think I agree with Luke's initial point, as clarified in the continued discussion with Lee.

Luke Roelofs said...

Sorry, 'unknown' is still me - Blogger keeps inviting me to use my google account, and then apparently can't actually do that when I accept. Anyway, if the claim is that externalists think the supervenience base does in fact (sometimes? often?) extend beyond the body, I guess I am somewhat in sympathy with Shelley in casting a very sidelong glance at why the discussion is focused specifically around disabled people. Either externalists think that the mind actually extends for abled people as much as it does for disabled people, in which cases it seems like wouldn't a more widely-shared sort of extending be a better example to focus on than one which only a minority have first-hand experience with, or they don't, in which case it looks like there are some pretty big assumptions about the nature of disability being made (e.g. that the social model of disability is false?).