Seasons

I disagree with A implying B above. That's like saying we have a theory (gravity) about what happens when an object falls. Reading about this theory means I can experience what it's like to fall from a 100-story building. No.

Or closer to yours: We have a theory for how people walk. Someone born with no legs can read this theory and understand what it feels like to walk.

Your argument requires the assumption that reading and understanding a theory of X is equivalent to experiencing X. Reading about how X works does not tell you how X feels.

My view of the double-slit experiment is very straightforward. A wave goes through two slits and is diffracted. It interacts with the detector screen in a punctiliar, probabilistic fashion. There is no particle that travels in a continuous trajectory (or several) from the source to the screen.

So you think there is no such thing as a photon, and that light only comes in waves? Now that would seem unorthodox these days (though a century ago I agree it was generally accepted.)
Or that it is distinctly wave or particle at one time but not at another? And that that time can be controlled by approaching it with a measuring device? The light, that has left its emitter as a particle, can effectively predict what sort of measuring device it's going to encounter, and configure itself accordingly? Because if you replaced the difraction grating with a photon detector, a photon is exactly what you'd detect.
That wouldn't be duality - it would be some kind of alternating state. An alternation whose primary purpose moreover would appear to be to make the universe more closely align itself to human concerns about "common sense" (or somesuch.) I tend to doubt the universe cares very much about fitting in with our prejudices - it certainly never went out of its way to provide us with a flat earth or an earth-centred solar system when it might have saved us much head-scratching and occasional anguish.

I sadly don't have a copy of Cohen-Tannoudji, Diu, and Laloe, Quantum Mechanics
to hand (I tend to rely on Penrose, Road to Reality for the most part, since it saves so many feet of bookshelf I'd otherwise need to cover a dozen different disciplines - a highly recommended "user guide" to the universe I might add,) but I will see if our library does have it, and check it out if I can (in fact, with a challenge like that, I'm determined to! )

Cohen-Tannoudji, Diu, and Laloe, Quantum Mechanics

Ouch! That's a week's wages on amazon, and I can confidently predict Swansea Library won't have diverted that much of their Mills & Boon budget to a serious subject. I don't suppose you've got a cheaper reference?

Dear Ulrike:

You write:

"Your argument requires the assumption that reading and understanding a theory of X is equivalent to experiencing X. Reading about how X works does not tell you how X feels."

I agree completely that "Reading about how X works does not tell you how X feels." But I don't think that the argument I gave in message 3748 presupposes it. On the contrary, as I explained in message 3753, the argument hinges on exactly the opposite assumption. Unfortunately, I cannot at the moment think of any way to make this point, except to rehash what I have already said, which seems pointless. I can only request that you go over the two messages again with an open mind. You are of course under no obligation whatever to do so.

I am not opposed to multi-location in principle. I believe that it is possible to give a consistent account of time-travel (though there is no evidence I know of that time-travel actually happens), according to which I could go back in time and shake hands with my earlier self. In such a case, I would be in two places at once. There would not be two of me, however.

I think we have found a break-point in the language (all languages are full of them. I'm half convinced that there is no disagreement of belief in the world whatsoever, than that which arises from the clashing of different linguistic models!) - I would accept that, but only because I would regard such definitions as effectively synonymous. Very well, you are in two places at once. The problem seems to be one solely of emphasis. I'm saying "two places manifesting one Irina", and you're saying "one Irina existing in two places". I think we can agree to agree on this? (though not, perhaps, on the meanings of "duality" and "alternation" )

IMCO (In My Curmudgeonly Opinion), there is such a thing as identity. It is the relation that each thing bears to itself, and to nothing else. The set {x,y} has one element if and only if x exists and is identical to y. If x exists and y exists but x is not identical to y, then {x, y} has two elements. Is there anything in this paragraph that you disagree with?

I would prefer to simply say the set is {x} - I'm happy to retract any emphasis of {x,x}, but I see y as completely redundant (if it refers to the object. If it referred to the spatial location, of course, then it must be {x,y} and x not=y.) There is no y, since there's only the one Irina. But in two places at once, as you say.
I believe your mind could be copied without perfect emulation of your entire body, to provide two (separate but real) Irina consciousnesses, but that's a different matter.

Cohen-Tannoudji, Diu, and Laloe, Quantum Mechanics

Ouch! That's a week's wages on amazon, and I can confidently predict Swansea Library won't have diverted that much of their Mills & Boon budget to a serious subject. I don't suppose you've got a cheaper reference?

Hmmm. They don't seem to have that as an ebook in my favorite online sharing libraries either.

If I go to MIT's open course page http://ocw.mit.edu/index.html
Can I just download the lecture notes for QPI? That takes up even less shelf space. Or would I miss too much?

Irina: I don't see how A can possibly imply B in message 3573 without making that assumption. That (for me) is the problem point.

It also just hit me that you can download a PE class at MIT. Reading about exercise must be a lot like reading about red. Would you rather do 100 crunches or just download the flat abs?

Ulrike:

Ah, I think I understand your objection better now!

The claim is that (A) in message 3753 implies (B). The argument itself therefore does not need to presuppose either (A) or (B). In fact, the argument is trying to establish that both are false.

But why would anyne thingk that (A) implies (B)? Well if subjective experience can be completely reduced to brain states, then then a complete theory of the relationship would imply all truths of the form, "Brain states of type X corelate with subjective states of type Y." If the theory is really complete, it would be able to describe what subjective states of type Y are like. How complete would a theory of arthropoda be that was unable to say what arthropoda were like? Now, Bevrina should then be able to find out by experiment what brain states people are in when they see red; she then goes to her Complete Neurophysiology book and finds the description of the subjective states that correspond to brain states of that kind. She can do this by reading (and applying) the theory, if there is such a theory.

But many people (including you, I gather) will object to the idea that she could learn what it is like to experience red by reading a theory book. For example, many people believe that the subjective (inner, experiential) appearance of redness is ineffable; it can't be described. They will conclude that no such book can exist, and no such theory can exist. In fact, many will argue that there is no way to know whether two identical twins with normal vision actually have the same inner experience, even though they are looking at a similar patch of red paint under similar lighting conditions. If they are right, then Bevrina could know all the neurophysiology there is to know, but she will never know what her friend Ekirlu experiences when Ekirlu sees something red, even though she has a scanner that tells her exactly what brain state Ekirlu is in at that moment.

But if
(i) Bevrina knows exactly what brain state Ekirlu is in, and
(ii) Bevrina knows the entire theory of brain/experience corelations, (and is intelligent enough to apply it)
but
(iii) Bevrina cannot figure out what Ekirlu is experiencing,
then it would seem to follow that
(iv) The theory of brain/experience corelations that Bevrina is using is incomplete.
For if it were complete, then it would tell her what a person is experiencing, when they are in the brain state that Ekirlu is in.

It is the believer in complete reductions of subjective states to brain states who is committed to (B).

Bev, Psimagus:

It is not necessary to read that very book. Virtually any recent textbook in Quantum Mechanics will have a chapter with a list of fundamental postulates. I like the CDL because is very clear and thorough. On the other hand, it would be nice if we were all working from the same text. You could borrow it and Xerox the passage in question.

Here's an argument, due to Thomas Nagel, which is similar to the Bevrina argument above and may therefore cast light on it (I am putting it into my own words):

Bats hear notes which are far too high for humans to hear. Let's say a Bat hears a note at a frequency of 35,000 Hertz; no human could hear such a sound. What does it sound like to the bat? What is the bat's experience of the sound like?

If we had a complete theory of the relationship between brain states and experiences, then we could scan the bat's brain and apply the theory to find out what the bat was experiencing.

But again, many people will claim that the bat's experience is ineffable. They will say that we can never know what a note of 35,000 Hertz sounds like to a bat.

If they are right, then we will never be able to have a complete theory of the relation between brain states and conscious experiences, for a complete theory would tell us what 35,000 Hertz sosunds like to a bat.

If you think they are wrong, please explain to me how we are going to scientifically determine what 35,000 Hertz sounds like to a bat.

Psimagus, Bev:

In fact, here is a quick list of six postulates that you can find on the net, absolutely free!

http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html