Quiddity has a qualia all its own
<p>I changed my mind about a significant philosophical issue today, and in the process parted ways with a thinker I&#8217;ve been a serious fan of for a couple of decades now.  The issue is raised by a thought experiment, of which I was previously unaware, called <a href="http://en.wikipedia.org/wiki/Mary's_room">Mary&#8217;s Room</a>.  The simplest way of getting involved the dispute is to ask &#8220;How can I know that my experience of (say) the color &#8216;red&#8217; is the same as yours?  Is it even possible to have such knowledge?&#8221;</p>
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<p>The deeper question this gets at is whether physicalist theories of mind are sufficient;  read the Wikipedia article linked above for the argument, I won&#8217;t rehash it here.  Until a few hours ago I would have, somewhat reluctantly, agreed with Daniel Dennett&#8217;s position that Mary doesn&#8217;t learn anything when she steps into the world of color.  I&#8217;ve long been a fan of Dennett&#8217;s bracing, unapologetic physicalism; I&#8217;ve especially enjoyed his witty takedowns of <a href="http://en.wikipedia.org/wiki/New_Mysterianism">mysterian</a> positions in the philosophy of mind. </p>
<p>My reluctance would have stemmed only from this: whether or not Mary actually learned anything when she first saw the color red, it seems certain to me that Mary would <em>feel</em> she had learned something. Dennett argues that with complete knowledge  of the physics of light, the range of red wavelengths, the history and significance of the color &#8220;red&#8221; to other human beings, Mary wouldn&#8217;t know anything about the world that she hadn&#8217;t known before.  </p>
<p>Under an operationalist, fallibilist account of &#8220;truth&#8221; &#8211; which I think is the only sane one &#8211; it&#8217;s at first hard to see how to argue with Dennet&#8217;s position.  The Mary&#8217;s Room experiment conveys the assumption  that Mary knows so much about &#8220;red&#8221; by indirection that she can make  predictions about events involving &#8220;red&#8221; as accurately as anyone else.  So if Mary says &#8220;Wow!&#8221; upon first actually seeing the color red, what does the &#8220;Wow!&#8221; mean?  </p>
<p>Dennet insists that Mary&#8217;s &#8220;Wow!&#8221; is meaningless &#8211; he seems to think he has to maintain that in order to defend physicalism against the mysterians.  This is where I now part company with him.  It certainly means something <em>to Mary</em>.  Any theory of mind that can&#8217;t support questions about that meaning <em>to Mary</em> is dangerously impoverished &#8211; Mary won&#8217;t buy it, for starters, and why should she?  Dennett thinks he&#8217;s robustly defending physicalism, but I think he&#8217;s surrendering the high ground to the mysterians.</p>
<p>The Wikipedia article offers an alternative answer based on some experimental work by two cognitive scientists working with a color-blind synesthete. I think the Ramachandran-Hubbard answer (Mary will have blindsight about color distinctions) is as mistaken as Dennett&#8217;s, because Mary (by hypothesis) is not color-blind.   But they did provide me with a vital clue.</p>
<p>The human brain actually includes two semi-separated signal-processing pathways for vision. One is luminance-oriented and good at picking up fine details: it &#8220;sees&#8221; in black and white, but very sharply.  The other is good at color distinctions but poor at processing shape details. The take from these two pathways is integrated at a late stage in processing, a fact on which depend several classic &#8220;optical illusions&#8221; and the continuing niche appeal of black-and-white photography in a world of cheap color film.  </p>
<p>Ramachandran-Hubbard&#8217;s color-blind synesthete is in the extremely odd position that he can have activations of his color-vision pathway from two different sources (his retina and the abnormal synesthesia pathways) which give him disjoint sets of color qualia.   Ack!  There!  I&#8217;ve said it: the dread word <a href="http://en.wikipedia.org/wiki/Qualia">&#8220;qualia&#8221;</a>, which in Dennett&#8217;s universe no self-respecting physicalist is supposed to utter without firmly insisting that it is meaningless!  </p>
<p>Have I, too, surrendered to the mysterians?  No.  In fact, not.</p>
<p>Here is my physicalist account of Mary&#8217;s &#8220;Wow!&#8221;  What she learns is <em>what it feels like to have the color-processing pathways of her brain light up</em>.  This is an objective fact about her subjectivity; with a sufficiently good MRI we could actually see the difference in patterns of occipital-lobe activity. And that will probably be a world-changing experience for Mary, fully worthy of a &#8220;Wow!&#8221;,  even if we concede the  Mary&#8217;s-Room premise that she has not learned anything about the world outside her own skull.</p>
<p>To see this, imagine being a precocious, prepubescent scientist who knows (objectively) everything all other human have reported about sex.  Now the hormonal switch flips, and you <em>feel</em> it&#8230;and nothing is the same, is it?</p>
<p>What I&#8217;m really arguing here is that Dennett, and thinkers like him, are stuck hard enough in a theoretical set of distinctions about &#8220;objective&#8221; vs. &#8220;subjective&#8221; to have ignored an important part of the phenomenology.  One&#8217;s own mental life &#8211; or, to put it physicalist terms, one&#8217;s perception of one&#8217;s own brain states &#8211; is part of the phenomenal field just as genuinely as Husserl&#8217;s copper ashtray is.</p>
<p>I&#8217;m proposing that, contra Dennett, there is a sense of the word &#8220;qualia&#8221; that is meaningful in physicalist terms.  A &#8220;quale&#8221; (singular form) is a brain state with the following properties: (a) like the abnormal activation of a colorblind synesthete&#8217;s color pathways in the occipital lobe, or like the first-ever feeling of sexual desire, it is in principle an objectively measurable event with detectable correlates in brain and body, and (b) it&#8217;s incommunicable.  </p>
<p>That is, I can learn to anticipate the phenomenal experience I will have when I look at something you have previously told me is &#8220;red&#8221;, but <em>I can&#8217;t tell you what that experience is</em>. Arguably, <em>all</em> brain states are incommunicable in that sense &#8211; but that&#8217;s actually part of my point; language and art and mathematics and music and so forth are all, in important ways, too narrow to shove our phenomenology through.  </p>
<p>The last laugh goes to Alfred Korzybski: the map is not the territory, the word is not the thing defined.  We can communicate linguistic and para-linguistic maps, but not the phenomenological territory &#8211; the qualia &#8211; from which we abstracted them.</p>
