Sunday, February 20, 2011

Double Rainbows

In a previous post, Carl mentioned the conundrum of whether two people can really see the same rainbow. This is really interesting because the look of rainbows, their "position" and "shape," etc are dependent on the perspective of the viewer. Just what exactly are we looking at when we look at a rainbow? Is the rainbow "just in our heads"? My feeling is that for rainbows, it really is just in one's head because I don't think there is anything substantive and definitive enough (either as a physical object or event or whatever) there for the term 'rainbow' to really "attach" to. Perhaps rainbows are like mirages, etc, only they can induce roughly the same images in different people in the same position at around the same time.


  1. Thanks for the follow up! Regarding your earlier comment, doesn't your position commit you to the view that the sky isn't blue and light of XX nanometers isn't really blue, since "seeing blue" happens with "S-fibers" in the head, not out in the world. It seems like the trouble is we have three things:

    The object - a blue sky, a compression of nerves in the leg
    The detection of the object in the brain - S-fibers firing, C-fibers firing
    The experience - seeing blue, feeling pain

    My view (following Whitehead in a jumbled and confused way) is that we can't locate the experience in a simple position. The experience is both in the head and in the world, on pain of solipsism if we don't allow one experience to be in two place. Even if seeing blue reduces/supervenes on S-fibers firing, we still need to talk about light of such-and-such nanometers as being blue.

  2. Hmm, that wasn't proofread very well.

    One more thought: what do we mean by "pain"? Do we mean the activation of nerve in the leg or the sensing of that activation in the brain? With sight, we say that "we see with our eyes." So, we see with the eyes. But on the other hand, there are people with brain damage that renders them "sight blind." They can still see physically, and the signal is, apparently, still being sent to their brains, since they retain some unconscious ability to guess what they're seeing, but they don't experience "seeing."

    So, I would say again that there are a number of components at work: the thing the eye is seeing, the eye, the transmission of the signal to the brain, and the recognition of the signal by the brain. In pain, there's the thing hurting your leg, the pain receptor in the leg that fires, the transmission of that signal to the brain (or brains for conjoined twins?), and the recognition of the signal by the brain. In both cases, I tend to find it overly Cartesian to say that only the last step "really counts" as seeing/feeling pain. It's not as though there's a homunculus in the Cartesian theater who only sees the last step in that chain. The whole chain has to be there for the experience to happen. So, it all counts as part of the experience.

  3. The term 'color' is ambiguous. I believe the distinction is Locke's where he distinguishes primary properties from secondary properties. The color blue, when construed a primary property, is objective and mind independent and may be scientifically realist in the sense that it reduces to a region of the electromagnetic wave spectrum, etc. Even if reductionism is true, it still makes sense to distinguish between the physical nature of light with the subjective sensation of a color. (I don't know if I got Locke's terms right but I know he made the kind of distinction relevant.)

    I think for rainbow, there is no objective "thing" to which it corresponds even though the colors can be said to have a primary objective existence qua light particles or waves. But the whole rainbow as an entity doesn't seem to me to be anything other than something in the viewer's mind.

    Pain, on the other hand, unlike color, seems to be objective and completely reducible or supervenable (sp?) on the physical processes, etc, if reductionism is true.

    If someone feels pain and they were to say that it isn't a neuro-chemical process in their brain or some part of their nervous system, it seems to me that assuming reductionism is true, he is saying something that his brain is misleading him to believe much as the person with phantom limb pain thinks his pain is in his missing limb when's it's just in his brain.

    In short, there really does seem to be two separate things we can mean by 'blue', a section of the electromagnetic spectrum (objective primary quality) or our sensation of blue (secondary and subjective). The two are not reducible. It makes sense to keep the distinction here.

    But assuming that reductionism of mind/brain-nervous system is true, the feel of pain (qualia and secondary property) is identical to the physical processes. Attribution of pain to a region of the body where it is felt would then be a mere illusion created by the mind or brain.

  4. I gave this a little more thought and it may be better to frame this in terms of "mind independence."

    Consider this: When we say "blue", we may mean one of two things, our inner sensation or "feel of what it's like" of blue or we may mean the electromagnetic radiation of a certain wavelength. The later is mind independent in the sense that if there had been no minds, there would still be electromagnetic radiation of all wavelengths and a fortiori of a particular range of wavelengths. SO it makes sense to posit blue independently of minds.

    Now consider pain. There is the sense or what it's like of pain but does it make sense to say that there is a mind independent sense of what we mean by pain? Some philosophers may defend that there could be this, for lack of better word, "free-floating" pain, but it seems implausible. It doesn't seem to be meaningful to have pain independent of minds.

    Now if reductionism is true, minds simply *are* brains or nervous systems. Since conjoined twins have separate brains and nervous systems (except for a small overlap in their peripheral nervous system) they seem to have different pains even if the pain seems like it is located in the same shared region of their conjoined bodies. The argument will seem to work mutatis mutandis for supervenience too.

  5. Interesting. I will think about it more.