Close Range: A Thought Experiment
Go read the set up. I'll wait.
Marc says that Option 1 (Kurt knows that p at t1, fails to know it at t2, knows it at t3, fails to know it at t4, … , knows it at tn.) "requires that knowledge be able to flicker in and out of existence over very short intervals of time. This seems to me like an immensely unattractive position."
Why is that such an unattractive position? A simpler case might be you tell me your phone number. After finding a paper and pencil, I write it down. I immediately forget it. When I need to call you, I look it up, but then forget the last digit as I'm dialing. I look again at what I've written and complete dialing. Later that day I forget it again. Eventually I've called you enough times that I no longer have to look it up.
Wouldn't it be a pretty ordinary way of looking at things to say that I knew your phone number when I wrote it down, I didn't when I had to look it up again, I did when I dialed it correctly, and so on? At each of those moments I have Justified True Belief--and yet it certainly looks like my knowledge flickers in and out of existence for cases much simpler than proofs that can only be apprehended at the barest edge of my mentally acuity.
Maybe I'm missing something , but it does seem to me that we know things even if they are only in our iconic memory, despite our knowing that they'll vanish immediately unless reinforced. If that weren't the case we'd have to deny knowing the appearance of something even when we're looking right at it--and to me that's also an immensely unattractive position.
In Fake Barn Country: Color in Dreams and Fiction, they're arguing about whether you dream in color, and can you be mistaken about that. (A bit of a coincidence, since my previous post on color perception was prompted by a thread on Sequential Tart )
The first thing that springs to mind is that nowadays it's probably possible to settle the question of dreaming in color empirically, by doing a PET scan while someone is dreaming.
The second thing is that what Jonathan is proposing (or agreeing with Ernie on) is really quite weird in light of, for instance, what the Damasios have written about color perception, memory, and language use. Normally, seeing, remembering seeing, and imagining seeing all activate the same parts of the brain. Destroy certain of those parts and you not only become incapable of seeing color, you become incapable of even imagining it any more. On the other hand, destroying the parts that let you assign names to colors, or speak words (including but not limited to those for colors) and you can still perceive, remember and compare colors non-verbally. Physiologically, then, dreaming without perception would seem to require that we dream using only the linguistic centers of the brain--i.e. that we dream in sentences, and confabulate the sensations that we seem to recall having in the process of remembering or recounting the dream. Another possibility would be that the visual centers would light up, but only those responsible for black-and-white imagery. That would be strange, but probably testable, although I'm not sure whether our current undertanding is that color vision is seperable from black-and-white vision as far as what the brain does (obviously there are people who lack color receptors in the retina, so they see in black-and-white, but I don't know if PET scans of their brains show any systematic differences from people with normal vision). Either that, or being in a dream state would somehow turn us into Zombies, where the visual parts of the brain would be doing all their usual stuff which when awake leads to perception and memory and sensation, but while asleep is simply neural activity unattached to qualia but generating memories that will have qualia attached if and when we reactivate them. This latter hypothesis does seem to me to be untestable, but also wildly implausible.
So why were people widely convinced prior to the 60's that dreams were never in color? I don't know. Did they really, or was that one of those stupid things like Behaviorism that only an intellectual could believe?
Hanna and Antonio Damasio have written about language and the perception of color, and three different kinds aphasia relating to color: achromatopsia, damage to the occipital region that prevents percieving or even imagining colors (this relates back to what I mentioned about the same areas being used both to see and remember seeing); lesions to left posterior temporal and inferior parietal cortex, which prevent proper formation of words ("buh" instead of "blue") but which affect all speech, not just color speech; and color anomia, damage to the temporal segment of the left lingual gyrus, which prevents you from being able to name any colors even though you still perceive and can match and discriminate between colors non-verbally. So, there seems to be a very specific locus where color perception gets coded as color language, but the perception can still go on normally even when the ability to encode the perception as language is destroyed.
Crooked Timber: What we don't notice... recounts an interesting experiment in perceptual framing and focus, where people who are shown a film and told to focus on a particular task (counting the number of times a team passes the basketball) don't notice something really obvious if unrelated to the task (a woman in a gorilla suit walking slowly through the players, stopping, thumping her chest, and moving on).
More evidence of just how much processing of our perception goes on beneath the level of consciousness, and the great extent to which conscious intention directs and shapes that processing.