Archive for November, 2006

Attentional Resolution

Thursday, November 30th, 2006

Consider the following figure from Cavanagh et al. (1998):

Fig. 1. Fixating on the center, attempt to count the lines by moving only your attention. This is much easier to do with the lines on the right.
Block (2001) writes, of the lines on the left:

[O]ne is phenomenally conscious of them. And one can say roughly how many there are. But, to the extent that one cannot attend to them, one cannot apply concepts to them, e.g. shape concepts.

Block’s idea here is that the attentional resolution effect helps support a distinction between phenomenal and access consciousness. The extent to which concepts cannot be empolyed to the lines on the left is the extent to which they cannot be individually attended. But note that there remain lots of ways in which concepts may nonetheless be applied to the lines on the left. To mention just one, consider conceiving of them as “the lines on the left.”

References:

Block, N. (2001). Paradox and Cross Purposes in Recent Work on Consciousness in Stan Dehaene, ed., The Cognitive Neuroscience of Consciousness, M.I.T. Press

Cavanagh, P., He, S., & Intriligator, J. (1998). Attentional resolution: The grain and locus of visual awareness. In C. Taddei-Ferretti (Ed.), Neuronal basis and psychological aspects of consciousness. Singapore: World Scientific

Abusing the Being-Knowing Distinction

Tuesday, November 28th, 2006

Amtrivalent

Originally uploaded by Pete Mandik.

Here’s a caricature of a familiar exchange:

Smith asserts P. Jones asks “yes, but how do you know P?” Smith says “Bah!” and “Do not confuse epistemology with metaphysics.”

In defense of Jones, consider these principles Jones can appeal to:

(A): It is observed that P. Scientific theory T explains P. But scientific theory T is inconsistent with the fact that P was observed. Too bad for T!

(B): It is intuited that P. Philosophical theory T explains P. But philosophical theory T is inconsistent with the fact that P is intuited. Too bad for T!

(There are weaker principles than A and B that Jones might appeal to. I have in mind here principles in which T is consistent with P but fails to explain the perception of/intuition of P, or, alternately, leaves utterly mysterious the explanation of the perception of/intuition of P.)

Example of A: I observe that a bright light has just flashed outside my apartment window. T = A nuke exploded just outside my window. T would explain a flash of light. But it certainly would not explain a flash of light observed by me. T instead implies my destruction and thus failure to observe that P. Too bad for T!

Examples of B? Clear examples are going to be a bit harder to come by, since the concept of intuition is much less clear than the concept of observation. Let’s stipulate a definition of intuition.

Intuiting P means believing P not as a consequence of observing that P and not as a consequence of any learned theory that includes or entails P.

So, if P is believed simply as a consequence of learning a language, and knowing a language isn’t knowing any theory, then that would be intuiting P. Also, being born believing P would count as intuiting P.

I’ll save the B examples for a later post. Brain Hammer readers are invited to provide their own in the comments.

Doubled Qualia

Tuesday, November 21st, 2006


Through a Glass Darkly

Originally uploaded by Pete Mandik.

Davidsonian supervenience is insufficient for physicalism, since it fails to rule out doubled qualia. Physicalism thus requires fine-grained supervenience to augment Davidsonian supervenience.

Davidsonian Supervenience:
(1) No two entities can differ at a time with respect to their mental properties without differing at that time with respect to their physical properties.
(2) No single entity can change with respect to its mental properties without changing with respect to its physical properties.

Fine-Grained Supervenience:
(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.

Doubled Qualia.
Doubled qualia occur when two minds, one whose qualia are inverted with respect to the other—a “green mind” and a “red mind,” respectively—share a supervenience base. What it means to share a supervenience base is that there are no physical differences in virtue of which the red mind and the green mind differ. Davidsonian supervenience, the conjunction of (1) and (2), does not rule out doubled qualia. To imagine doubled qualia, begin by imagining someone other than you, Person X, who is not your physical doppelganger. Let us stipulate that there is some physical difference between you and Person X. Unlike you, let us suppose, there are two minds inside of Person X—a red mind and a green mind—where you only have the standard-issue red mind. Suppose further that all and only the physical properties that give rise to X’s red mind are the same physical properties that give rise to X’s green mind. If you are having a hard time imagining this, that is likely due to your tacit or explicit acceptance of FGS. Your acceptance of (1) and (2) can’t explain this. In particular, the difference between you and X—the fact that you have only a red mind where X has a green one as well as a red one—is fully consistent with (1), since we have stipulated that there is a physical difference between you and X. Do you think that doubled qualia are weird? If so, then you will find the following intolerably bizarre.

Intermittently Doubled Qualia.
To get warmed up for intermittently doubled qualia, stop to appreciate the following stipulation about Person X: the red mind and the green mind need not have any awareness of each other whatsoever. What this means, then, is that for all you know, your qualia are doubled right now. For all you know, there’s someone else “in there” with you right now and what it’s like to be them is just like what it’s like to be you except for the inversion of the color qualia bit. Now, imagine further, that you undergo the following recurring physical change. The set of physical properties P1, that suffice to instantiate just the red mind are replaced by a set of distinct physical properties P2, that suffice for both a red mind and a green mind. So, according to the intermittent doubled qualia thought experiment, you change from P1 to P2 and back again which changes you from un-doubled qualia to doubled qualia and back again.

Perhaps you think that intermittently doubled qualia are impossible. You may be right. But here’s one thing that won’t rule them out: clause (2) of supervenience. Clause (2) prohibits you from changing mentally without changing physically, but the intermittent doubled qualia thought experiment stipulated that there were physical changes accompanying the change to a doubled state. Davidsonian supervenience rules out only some of the obvious impossibilities concerning qualia. (1) rules out (a) inverted and (b) absent qualia. (2) rules out (c) fading qualia and (d) dancing qualia. Neither (1) nor (2) rules doubled qualia. And I’m betting physicalists would very much like to rule out doubled qualia. Then physicalists should explicitly embrace FGS.

Warning: Explicit Content

Tuesday, November 21st, 2006

I just noticed this over at Online Papers in Philosophy: Dan Dennett’s “The Evolution of ‘Why?’ - Essay on Robert Brandom, Making it Explicit“.

Excerpt:

We both learned a lesson from Wilfrid Sellars that still hasn’t sunk in with many of our colleagues.   I quote, not for the first time, what I consider to be the pithiest expression of it in Sellars:

My solution is that “. . . .’means’ - - -” is the core of a unique mode of discourse which is as distinct from the description and explanation of empirical fact, as is the language of prescription and justification. (Chisholm and Sellars, 1958, p527Bdiscussed briefly by
me in 1987, p[341)

The ineliminable,  foundational normativity of all talk of meaning or intentionality was first insisted upon by Sellars, and Brandom’s version of the reason for this is comprehensive and detailed.  Brandom chooses to adopt my “intentional stance” way of characterizing this unique mode of discourse,   since the evaluative or normative presuppositions can be readily seen to be built right into the rules of that game.  He then draws a distinction between simple intentional systems (what I call first-order intentional systems, entities whose behavior is readily interpretable by ascribing beliefs, desires and other intentional states to them) and interpreting intentional systems (what I call higher-order intentional systems, capable of ascribing intentional states to others and to themselves).   Now which kind comes first?

The Neurophilosophy of Subjectivity

Monday, November 20th, 2006

Mandik, P. (in press). The Neurophilosophy of Subjectivity. In John Bickle (ed.), Oxford Handbook of Philosophy and Neuroscience. New York: Oxford University Press.

ABSTRACT: The so-called subjectivity of conscious experience is central to much recent work in the philosophy of mind. Subjectivity is the alleged property of consciousness whereby one can know what it is like to have certain conscious states only if one has undergone such states oneself. I review neurophilosophical work on consciousness and concepts pertinent to this claim and argue that subjectivity eliminativism is at least as well supported, if not more supported, than subjectivity reductionism.

[Link to full text of article]

P.S. People who love (hate) Hyperbolic Mary may be interested in this article. She appears toward the end of it and it provides some further context for why she’s supposed to matter.

Hyperbolic Mary

Friday, November 17th, 2006

Flow Crash

Originally uploaded by Pete Mandik.

Paul Churchland, in his recent “Chimerical Colors: Some Novel Predictions from Cognitive Neuroscience” (2005), describes very odd color experiences that are predicted by a neural model of chromatic information processing. In brief, the differential fatiguing and recovery of opponent processing cells gives rise to afterimages with subjective hues and saturations that would never be seen on the reflective surfaces of objects. Such “chimerical colors” include shades of yellow exactly as dark as pitch-black and “hyperbolic orange, an orange that is more ‘ostentatiously orange’ than any (non-self-luminous) orange you have ever seen, or ever will see, as the objective color of a physical object” (p. 328). Such odd experiences are predicted by the model that identifies color experiences with states of neural activation in a chromatic processing network. Of course, it’s always open to a dualist to make an ad hoc addition of such experiences to their theory, but no dualistic theory ever predicted them. Further, the sorts of considerations typically relied on to support dualism—appeals to intuitive plausibility and a priori possibility—would have, you’d expect, ruled them out.

Who would have, prior to familiarity with the neural theory, predicted experiences of a yellow as dark as black? One person who would not have thought there was such an experience as pitch-dark yellow is Ludwig Wittgenstein, who once asked “[W]hy is there no such thing as blackish yellow?” (1978, p. 106). I think it safe to say Wittgenstein would be surprised by Churchland’s chimerical colors. At least, I know I was, and I literally grew up reading Churchland. However, to be certain that we have an example of someone who is surprised—for I would like to conduct a thought experiment about them—let us consider someone, call him “Larry”, who has seen yellow and black and in general all the typical colors a normally sighted adult has seen. Suppose that Larry has never had a chimerically colored afterimage such as hyperbolic orange or pitch-dark yellow. Suppose further that Larry is aware of none of the neuroscience that predicts the existence of such experiences. Now, let us compare Larry to Hyperbolic Mary. Like Jackson’s Mary, Hyperbolic Mary knows all of the physical facts about how human color vision works, including the predictions of chimerically colored afterimages. Suppose also, that like Mary toward the end of Jackson’s story, Hyperbolic Mary has been let out of the black and white room and has seen tomatoes, lemons, grass, cloudless skies, and the like. In short, she has had the average run of basic color experiences. Let us stipulate that she has had all the types of color experiences that Larry has had. The crucial similarity between Mary and Larry is that not only have they seen all of the same colors, neither has had chimerically colored afterimages. Neither has experienced hyperbolic orange or pitch-dark yellow. The crucial difference between Larry and Hyperbolic Mary is that only Hyperbolic Mary is in possession of a theory that predicts the existence of hyperbolic orange and pitch-dark yellow. And here’s the crucial question:

Who will be more surprised upon experiencing chimerical colors for the first time, Larry or Hyperbolic Mary?

I think it’s obvious that Larry will be more surprised. I also think this has pretty significant implications for what we are to think the knowledge of what it is like consists in. One thing that knowing what it is like consists in is something that will determine whether one is surprised or not. Fans of Jackson’s Mary must grant this, for they are fond of explicating Jackson’s Mary’s ignorance of what it is like in terms of her alleged surprise at seeing red for the first time. Well, Hyperbolic Mary is less surprised than Larry on seeing chimerical colors for the first time. This shows that she must have more phenomenal knowledge—more knowledge of what it is like to have certain experiences—than did Larry. Mary was able to represent, in introspection, more properties of her experiences than Larry. And her introspective capacity was augmented by her neuroscientific concepts.

References:
Churchland, P. (2005). “Chimerical Colors: Some Novel Predictions from Cognitive Neuroscience.” In: Brook, Andrew and Akins, Kathleen (eds.) Cognition and the Brain: The Philosophy and Neuroscience Movement. Cambridge: Cambridge University Press.

Wittgenstein, L. (1978). Some Remarks on color, ed. G.E.M. Anscombe, Oxford: Blackwell.

PMS WIPS 005 - Nicholas Maxwell - Three Philosophical Problems about Consciousness and their Possible Resolution

Wednesday, November 15th, 2006

“Three Philosophical Problems about Consciousness and their Possible Resolution” by Nicholas Maxwell, University College London.

ABSTRACT: Three big philosophical problems about consciousness are: Why does it exist? How do we explain and understand it? How can we explain brain-consciousness correlations? If functionalism were true, all three problems would be solved. But it is false, which means all three problems remain unsolved. Here, it is argued that the first problem cannot have a solution; this is inherent in the nature of explanation. The second problem is solved by recognizing that (a) there is an explanation as to why science cannot explain consciousness, and (b) consciousness can be explained by a different kind of explanation, empathic or “personalistic” explanation, compatible with, but not reducible to, scientific explanation. The third problem is solved by exploiting David Chalmers’ “principle of structural coherence”, and involves postulating that sensations experienced by us - visual, auditory, tactile, and so on - amount to minute scattered regions in a vast, multi-dimensional “space” of all possible sensations, which vary smoothly, and in a linear way, throughout the space. There is also the space of all possible sentient brain processes. There is just one, unique one-one mapping between these two spaces that preserves continuity and linearity. It is this which provides the explanation as to why brain processes and sensations are correlated as they are. I consider objections to this unique-matching theory, and consider how the theory might be empirically confirmed.
[Link to full text of article]
[Link to further info on PMS WIPS]

Dennett’s OK

Friday, November 10th, 2006

Dan Dennett is alive and well and has recently written about his medical adventures and who he has to thank for his survival. (Hint: Not God!) Check it out over at the Edge.

Banana Blues

Friday, November 10th, 2006

Gray bananas look more yellow than equally gray non-bananas. Your conceptual categorization of a stimulus as a banana has something to do with the perceptual appearance of the stimulus. But what more can be said about this “having something to do with” stuff? More later.

Fig. 1. These bananas are bluer than they seem.

Karl Gegenfurtner and his colleagues did some pretty convincing experiments on this stuff.

We asked human observers to adjust the color of natural fruit objects until they appeared achromatic. The objects were generally perceived to be gray when their color was shifted away from the observers’ gray point in a direction opposite to the typical color of the fruit. These results show that color sensations are not determined by the incoming sensory data alone, but are significantly modulated by high-level visual memory.

I saw Gegenfurtner demonstrate some of this in a talk he gave at the Pasadena Neurophilosophy conference in June ‘05. Gray bananas did indeed look more yellow than their equally gray non-banana counterparts.

So, what’s going on here? One hypothesis, call it the “phenomenal hypothesis” is that the activation of “high-level visual memory” influences, but is in no way constitutive of, the appearance. Another, call it the “conceptual hypothesis” is that the activation of high-level visual memory partially constitutes the appearance. I favor the latter hypothesis. Why? More later. Which do you favor? Why?
Reference: Hansen, T., Olkkonen, M., Walter, S. & Gegenfurtner, K.R. (2006). Memory modulates colour appearance. Nature Neuroscience, DOI:10.1038/nn1794.

Knowledge Intuition Fight Club

Wednesday, November 8th, 2006


Negotiation Breakdown

Originally uploaded by Pete Mandik.

In “Wanted: An Actual Argument for the Knowledge Intuition” I pitted KI (”One cannot know what it is like to have an experience of a certain type unless one has had an experience of that type”) against bold claim BC (”No one has ever given an argument for the Knowledge Intuition”). All commentators provided much useful feedback. Some commentators questioned whether KI was something anyone would find plausible or relevant and other commentators provided some interesting counterexamples to BC.

Now for round two.

In this corner, in the red trunks, we have:

(KI+): There exists at least one type of experience such that one cannot know what it is like to have it unless one has had an experience of that or some relevantly similar type.

And in the other corner, in the black and white trunks, we have:

(BC+): No one has ever given an argument for KI+.

Rules:
1. Don’t talk about Knowledge Intuition Fight Club
2. Single-premise existential generalizations are not welcome.
3. Arguments for KI+ that have premises concerning phenomenal concepts, phenomenal beliefs, and their brethren should specify what those things are in ways such that assertions of their existence aren’t simply different ways of stating KI+.