Archive for the ‘Subjective Brain’ Category

Points of Power

Wednesday, November 28th, 2007

I haven’t entirely uploaded my mind to PowerPoint since my necktop’s USB port has a glitch, namely, total existence failure. In the meantime I offer the following tidbits to current students and others whose brains burn with the question: where can we get the slides that go along with lectures on chapters 7 & 9 of The Subjective Brain? Right here, dudes and ladies, right here.

Reductive and Representational Explanation in Synthetic Neuroethology [link to download]

The Neurophilosophy of Subjectivity [link to download]

Just the Phacts, Ma’am.

Monday, September 24th, 2007



Recycle

Originally uploaded by Pete Mandik

Eric Schwitzgebel and I have been having an interesting (to us, at least) exchange in the comments on his recent post “Three Reasons to Mistrust Reports about Ongoing Conscious Experience“. At issue in our exchange are questions concerning introspective reliability concerning phenomenological facts or “phacts” as I called them. Eric is somewhat famous now for his many interesting arguments against introspective reliability. I tend to side with people who think that there are important senses in which introspective judgments can’t be wrong.

An interesting case, and one that Eric raises, concerns people’s judgments about the nature of their visual field. More specifically, people tend to vary over times and across subjects in their judgments concerning how much of the visual field is clear. The determinate colors and shapes of peripherally presented objects cannot be seen clearly. But people vary in their opinions about whether this is so.

Key question: do people vary in their accuracy of judgments of the phacts of the matter? That is, do some but not all of them get the phacts right?

The answer to the key question depends, of course, on what the phacts are. And one possibility that needs to be dealt with is that the variation in judgments is matched by a corresponding variation in phacts. On an extreme version of this possibility, everyone is right, they’re just right about different phacts.

One way to characterize resistance to this possibility is as interposing a third realm between a first realm constituted by objective facts concerning stimuli and sensory receptors and a second realm constituted by various conceptualized reactions to stimuli. Supplying a third realm gives something for items in the second realm to be mistaken about yet, unlike items in the first realm, look like candidates for genuine phenomenology. A lot of what Eric claims people to be mistaken about look to me to not be mistakes about phenomenology, but instead mistakes about what’s going on in the first realm (or mistakes about relations between the first and second realms).

Worries about a third realm can be put by saying that we really have no idea what sorts of denizens would populate it. In the case of the visual field, third-realm denizens would include peripheral objects that are colored and shaped but have no determinate color and no determinate shape. Do we really understand the suggestion that there can be such objects? And aside from questions about what objects would be, there are the various questions that arise about where they would be. No one’s ever found anything like that in anyone’s brains, and the items that populate our external environments certainly don’t fit the description.

It’s not enough to motivate the postulation of the third realm to say that we already know what it is, that it’s whatever makes it the case that there’s something it’s like to be conscious. Nor is it enough to counter skeptical resistance by characterizing that resistance as requiring reductive definitions. Reductive definitions are beside the point at this stage in the game, we just want something informative to “what are you talking about?” kinds of questions. No one has a reductive definition of a duvet, but could probably say something more informative about duvets beyond “if ya gotta ask, ya ain’t ever gonna know” kinds of responses.

The most pressing challenge for friends of the third realm is to say something informative about it such that it would be something separate from the second realm. This is because the second realm seems to be best suited for handling the sorts of weird indeterminacies that arise for phacts – indeterminacies like being indeterminately colored or having an indeterminate number of speckles.

See also:
[How do you know that you know what you are talking about when you talk about qualia?]
[Transcending Zombies]

Fine-Grained and Strong Supervenience

Tuesday, September 18th, 2007

Call “Fine-Grained Supervenience” or FGS the following:

(FGS): If, at a given time, a single entity instantiates two distinct mental properties, it must do so in virtue of instantiating two distinct physical properties.

Note how different this is from formulations such as this formulation of “strong” supervenience discussed by Wilson (2005, p. 433), wherein it is “formulated as holding between families of properties A and B, elements of which are co-instantiated in individuals in a domain D:
strongsuperv.gif

FGS is not entailed by formulations such as strong supervenience. Instead, strong supervenience is compatible with the falsity of FGS. We might state this compatibility in the following way. Whereas strong supervenience is compatible with multiple realizability insofar as there might be a physical property, b*, other than b that suffices for a, strong supervenience is compatible with the falsity of FGS insofar as there might be some mental property, a*, other than a that b suffices for.

Reference:
Wilson, J. 2005. Supervenience-based Formulations of Physicalism. Nous, 39:3, 426-459.

See also:
Mandik, P. In progress. The Subjective Brain, Chapter 1: The Metaphysics of the Neuron. [link]

Neuro-introspection and Multiple Realization

Friday, September 14th, 2007

In Chapter 2 of The Subjective Brain, I defend the Neuro-introspection thesis whereby brain states are introspectible as such. An objection I owe to Dan Cavedon-Taylor concerns whether the alleged multiple-realizability of the mental by the neural (MR) would be inconsistent with Neuro-introspection. The way Dan puts it is available here and I reproduce my response below.

Regarding MR, due to arguments set forth in ch. 1, I don’t take it particularly seriously. But considering my introspection thesis in isolation from ch. 1, I can grant, for the sake of discussion, relatively strong versions of MR. Since I think perception and introspection are analogous in many significant ways, it is useful to consider the MR issue by constructing an analogy to perception. Suppose there is some object type that is not only multiply realizable but multiply realized. Suppose further that the object type bottle is one such example. So there are lots of distinct physical realizers of bottles, e.g. glass ones and aluminum ones. But this supposed fact (the multiple realizability of bottles) is not all by itself a problem for standard accounts of object perception. There’s not an obvious problem of how one can perceive not only that a bottle is present but that a glass bottle is present, is there?

Perhaps you think my example concerning glass vs. aluminum is a poor one since glass and aluminum are readily perceptually distinguishable. Suppose then that we switch examples to perceptually undetectable realization differences, e.g. two kinds of glass that can only be distinguished with special instruments. Now we have an example in which some properties of bottles are imperceptible. But this doesn’t raise any special problems for a theory that claims that bottles are perceptible. It’s pretty obvious that even though perceptible objects must have perceptible properties, they may nonetheless have imperceptible properties as well. I offer, then, that an analogous thing is true of introspection: neural states have neural properties that are introspectible, but perhaps they also have some neural properties that are introspectively undetectable. How does that show the failure of neuro-introspection?

Links: [The Subjective Brain draft chapters] [discussion page for Chapter 2]

Subjective Brain Ch. 9

Thursday, August 9th, 2007

The ninth and final chapter of The Subjective Brain, “The Neurophilosophy of Subjectivity” is up.

Excerpt:

What, in the context of the philosophy of mind, is subjectivity? Subjectivity has something to do with consciousness, but it is not consciousness itself. Subjectivity has something to do with the so-called phenomenal character of conscious states, but it is not identical to phenomenal character. Subjectivity is an alleged property of phenomenal character, namely, the property of being one-way knowable. More specifically, the claim that phenomenal character is subjective is the claim that the only way to know some phenomenal character is by having a conscious experience that has that character. (This is a first pass and will be refined further later.) Whatever the relevant sense of “know” is here, it is the sense relevant to “knowing what it is like” to have some conscious experience.
[...]
A neurophilosophical proposal such as Beaton’s constitutes an attempt to provide a reduction of subjectivity to aspects of neurophysiology insofar as it seeks to identify properties such as one-way-knowability with certain aspects of the functioning of the nervous system. A different neurophilosophical approach, and the one advocated in this chapter, is one that attempts to eliminate subjectivity by arguing (1) that there are no aspects of neural function with which so-called one-way-knowability can plausibly be identified and (2) no reason for maintaining a belief in the irreducible existence of subjectivity.

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Subjective Brain Ch. 8

Tuesday, August 7th, 2007

Chapter 8 of The Subjective Brain, “The Neural Accomplishment of Objectivity,” is up.

Excerpt:

Philosophical tradition contains two major lines of thought concerning the relative difficulty of the notions of objectivity and subjectivity. One tradition, which we might characterize as “Cartesian”, sees subjectivity as comparatively less problematic than objectivity. On the Cartesian view, what we know best of all are the contents of our own minds and the major problematic is to pierce the veil of appearances and make contact with objective mind-independent reality. In contrast is a line of thought that reverses the order of difficulty. A pervasive materialistic and scientific mind-set takes objectivity as the unproblematic starting point. From this point of view, widespread through much of contemporary philosophy and especially explicit in the philosophy of mind, a world of physical, chemical, and biological events is taken as relatively given. The problematic here then is to make sense of any kind of genuine subjectivity within this physicalistic framework.

One might expect neuroscientists and neurophilosophers alike to belong exclusively to this latter tradition, given their proclivity for seeing the mind as being intimately tied to, if not identical to, the brain—a physical thing presumably exhaustively describable in the objective idiom of physicalistic science. However, this is not so. Many practitioners of things neural count among adherents of what I have described as a Cartesian line of thought. This is especially clear when we recognize that the neural equivalent of the subjective/objective distinction is the egocentric/allocentric distinction. Egocentric representations, associated especially with activity in Posterior Parietal Cortex, code for things in “self-centered” reference frames. Allocentric representations (alleged by many to be involved in Hippocampal activity) in contrast, code for things in “other-centered” reference frames. Cartesians in neuroscience and neurophilosophy cast the egocentric as the relatively basic and unproblematic of the two sorts of neural representation. From this view, then, the allocentric is seen as especially difficult, and, under certain descriptions, impossible. My purpose in this chapter is to review and ultimately counter this Cartesian line of thought.

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Subjective Brain Ch. 7

Thursday, August 2nd, 2007

Chapter 7 of The Subjective Brain, “Animat Semantics” is up now. [link]

Excerpt:

An animat is an artificial animal, either computer simulated or robotic. Animat methodology involves three characteristic explanatory strategies: synthesis, holism, and incrementalism. The synthetic element involves explaining target phenomena by attempting to synthesize artificial versions of them, a characteristic inherited in large part from earlier versions of Artificial Intelligence (Good Old Fashioned Artificial Intelligence (GOFAI) as well as connectionist approaches). The holism referred to here is not necessarily restricted to the semantic holism familiar in other areas of philosophy of mind or cognitive science but is instead concerned with function more generally. The holistic take on function is that the function of an organ or a behavior is best understood in the context of the whole organism, or, more broadly still, in the context of the organism’s physical and/or social environment. It is thus both embodied and embedded (Clark 1997). However, this holistic impulse might seem to conflict with attempts to synthesize phenomena. Synthesis must simplify to be tractable, yet whole organisms are more complex than their subsystems, and social systems and ecosystems are even more complex. An older strategy of simplification involves focusing on subsystems of human cognitive processes, for example, as was done in GOFAI and connectionist models of word recognition. The comparatively newer strategy of simplification embraced by the Animat approach involves focusing on the entirety of organisms much simpler than the human case, thus heeding Dennett’s rallying cry/question, “Why not the whole iguana?” (1998: 309). In animat research projects of synthesis involve modeling the simplest intelligent behaviors such as obstacle avoidance and food finding by chemotaxis. The incrementalism of the animat approach involves building up from these simplest cases to the more complex via a gradual addition of complicating factors, as in, for instance, roboticist Rodney Brooks’(1999) ongoing project of building an incrementalist bridge from robotic insects like Attilla through to the humanoid robot, Cog.

Subjective Brain Ch. 6

Monday, July 23rd, 2007

Chapter 6 of The Subjective Brain, “The Allocentric-Egocentric Interface Theory of Consciousness” is here.

Excerpt:

In brief, the theory posits that mental processes form a hierarchy of mental representations with maximally egocentric (self-centered) representations at the bottom and maximally allocentric (other-centered) representations at the top. Part of what it means to be higher or lower in the hierarchy is to be further from or closer to the sensory and motor periphery of the nervous system. Focusing on the processing of sensory information, we can trace the path of information from relatively egocentric representations of the stimulus in sensation through stages of processing that increasingly abstract away from egocentric information and represent things in memory in an allocentric way. Further, we can note top-down effects from relatively allocentric representations high up in the hierarchy to egocentric representations lower in the hierarchy. I hypothesize that phenomenally conscious mental states are to be identified with states that are relatively intermediate in this hierarchy. More specifically, conscious states are hybrid states that involve the reciprocal interaction between relatively allocentric and relatively egocentric states: a conscious state is composed of a pair of representations interacting at the Allocentric-Egocentric Interface.

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On Not Splintering Appearances

Monday, July 23rd, 2007

Eric Schwitzgebel, as usual, illuminatingly plumbs the depths of introspective error at his Mind Splinters blog. Of particular recent interest are reports of some exchanges he’s been having with Dan Dennet over how to reconcile the possibility of introspective error with the sorts of authorial authority granted to the introspector by Dennettian heterophenomenology and first-person operationalism. (Schwitzgebel’s most recent post is here, which is a follow-up to this earlier post here.)

I think Schwitzgebel is on to something when he suggests we try to draw the distinction between what errors can and cannot be made in terms of a distinction between phenomenal judgments and what’s “behind those judgments”. I think, however, he missteps in his description of such a distinction in terms of two senses of “seems”. Dennett is no friend of the phenomenal/epistemic distinction between senses of “seems” that many philosophers follow Chisholm and Jackson in drawing. Also worth keeping in mind is Dennett’s negative reaction to so-called “real seemings” expressed in Consciousness Explained and elsewhere.

So how best to flesh out Schwtzgebel’s insight regarding Dennett interpretation? I think one can do this with a single (epistemic) sense of “seems” and a distinction regarding the way’s things are with regard to our seemings.

To give a very clear illustration of this distinction, consider a substance dualist who judges a piece of wax to be melting in the heat of their fireplace. One way things are with respect to the dualist’s seemings is that it seems like he can tell by sight that the wax has changed shape. And about this they are correct: it does seem he can tell by sight that the wax’s shape has changed. But another way things are with respect to the dualist’s seemings is that they, the seemings, are identical to brain states. And about this the dualist is quite wrong (or, more humbly, clearly might be wrong).

To relate this to an example discussed by both Schwitzgebel and Dennett, consider the case of peripherally presented playing cards which, to the surprise of many subjects, cannot be identified by suit or even color (though their motion may be readily apparent). I urge that we avoid cleaving senses of “seems”. We should not describe the case as it epistemically seeming to subjects that the periphery is clear and phenomenally seeming blurry. Instead we should say the following:

It seems to the untutored observer that he or she has detailed information about the color and suit of peripherally presented cards. However, in reality the subject does not have detailed information about the color and suit of peripherally presented cards, even though it may really seem that way to the subject.

[See also, some of my earlier posts on senses of "seems": Bursting Apart at the Seems; Bursting at the Seems 2: Electric Boogaloo; Transcending Zombies.]

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On the So-Called Directness of Neuro-Introspection

Wednesday, July 18th, 2007



Blast Radius

Originally uploaded by Pete Mandik

Dan Cavedon-Taylor raised some pretty interesting questions here regarding whether the neuro-introspection I defend in Ch. 2 of The Subjective Brain is, as Paul Churchland puts a similar thesis, “direct”. Instead of leaving my response buried in an old-ish comment thread, I reproduce it here:

I think most if not all that needs to be said about the relevant issues concerning perception can be done in terms of a three-way distinction (a tristinction!) between sensation, perception, and inferences based on what’s perceived. A similar tristinction may be drawn between sensation, introspection, and inferences based on what’s introspected. Sensations are non-conceptual and carry information about themselves and their causes. Perceptions are conceptual and involve the automatic conceptual exploitation of information that sensations carry about their causes. Introspections are conceptual and involve the conceptual exploitation of information that sensations carry about themselves. Inferences involve the non-automatic application of concepts.

I try to illustrate all of this stuff in terms of the story of George, John, and the man in the gorilla suit in section 3 of chapter 2. George, the special effects expert, and John, the novice, both have the same sensations, I suppose. George is able to see the person as a man in a gorilla suit. I might just as well say that George is able to see that this is a man in a gorilla suit. John is able only to infer, based on what he perceives (plus what George tells him), that this is a man in a gorilla suit. This is not to deny, however, that John is incapable of seeing this as something or seeing that something is the case. John may being seeing this as a living organism.

I’m not particularly thrilled about the vocabulary of “direct” and “indirect”. A lot of what some people want to call direct perception I would call “sensation” and a lot of what some people want to call indirect perception I wouldn’t call perception at all, but conclusions of inferences. I worry about certain baggage associated with “direct”, in particular, the view that there can be unmediated epistemic access to anything. That strikes me as a nutty view and I don’t want to be read as assuming its truth.

Ok, now to explicitly address your points and questions:

You ask: “[D]o we *see* heat? We can *see that* something is hot (again by seeing some feature of it). Do you think seeing heat and seeing that something is hot are the same? The first sounds direct, the second–indirect.”

Let me start by saying that I assume seeing to be a kind of perceiving. So, visual sensation alone would not count as seeing. Further, I acknowledge a distinction between seeing heat and seeing that something is hot. I also take this to be the same distinction as that between seeing heat and seeing heat as heat. I don’t think, however, that there’s such a thing as seeing heat without seeing it as something or without seeing that something is the case. A visual sensory response to heat without concept application would be sensation, not seeing. I really don’t know how best to apply the “direct” and “indirect” vocabulary to these kinds of cases. Is the direct thing the sensation? Or is it the seeing of the heat as something but not seeing it as heat? I propose to just do without that vocabulary.

You propose:
“[P]erceiving the heat of the coffee by perceiving its steam looks like a case of *indirect* perception (i.e. the claim seems to be I perceive x by perceiving y)”

Another way of describing what’s going on in the coffee case is that I have a visual sensation which is caused by hot steam and thus carries information both about the presence of heat and of steam and I perceive (visually!) both heat and steam though none either more or less directly than the other. (I think I need to be much clearer about this in a revised version of the chapter.)

Regarding introspection, you ask:
“[I]n what sense can the introspection of one’s brain states be direct if it is mediated by mental states? I take it the neuro-introspectionist doesn’t claim that one could introspect their brain states without introspecting mental states. Rather, they claim we introspect brain states as such by first introspecting mental states (again, this sounds like such introspection of brain states is thereby indirect). Or am I wrong??”

Here’s how I’d describe what’s going on. Sensation is one mental state. When I introspect the sensation, that involves a second mental state, which itself is a conceptual representation of the first state. Also, the occurrence of the second state must be an automatic response to the first state. Now, some people who don’t hate the word “direct” would say that the introspection is direct insofar as it is automatic. Others would say it is not direct because it involves a representation. I prefer to say what’s going on without using the word “direct”.

Raising some interesting concerns about modality individuation, you write:
“I would have thought that if heat perception is to be direct, then the sense modality through such an experience is afforded is going to have to be tactile, rather than visual (otherwise it just sounds a bit like a category error).”

I think the distinction between dermal thermoreceptors and retinal photoreceptors will be important for distinguishing between seeing heat and feeling it. But I don’t see that much work can be done about directness in terms of receptors. Patterns of activity in the retina carry information about all sorts of stuff, like what color it is, how hot it is, whether it was manufactured in China, etc. Anything I can figure out by looking at something must involve information that passes through my retina, so I’m not optimistic that one can settle questions concerning directness in terms of what can and cannot be transduced at the site of reception. But then again, I don’t feel particularly motivated to settle questions concerning directness, at least, not in the vocabulary of “directness”.