Do you think it's possible that the word "exist" is overloaded?
In what sense does snow "existA" but love does not "existA?"
In what sense does "reality exist?" Is this tautology? If so, state it.
"This is the point missed by the postmodernist folks screaming, "But how do you know your beliefs are true?""
Does setting up straw men serve some sort of emotional purpose? Why do you keep doing it? You haven't performed an analysis of the "postmodernist position" - you just keep pointing fingers and saying "they're dumb."
The (non-moron) post-modernist folks are screaming "How do we even know that 'reality exists?' Obviously we do not -know- so it must be definition embedded in cultural/computational context. Therefore when we make statements like "snow is white" what we really -mean- is the set of cultural/computational primitives that that statement can be reduced to. There is no other sense in which the word "mean" makes sense."
What about self-referent phenomena? Are you actually claiming that no beliefs are disjoint from so-called "logical definitions?"
In what sense does "reality exist?" Is this tautology?No, contradiction. There is nothing for reality to interact with, and so it cannot be said to exist.
Where is the universe? What color is half-past-three? How many zeros does it take to make a baker's dozen?
(Strangely, the comment list seems to have vanished - so I'll not consider myself bound by the previous stricture until it returns.)
Can we make statements of the form "X is Y" without the statement "X exists" being true? Because Eliezer does about reality - therefore I assume there is some sense in which he believes it to "exist." Note that my questions were directed towards his definition, not the claim itself (since I still obviously don't understand the way that Eliezer uses words).
To answer your questions:
"Where is the universe?"
Right here.
"What color is half-past three?"
For certain definitions of color in certain logical frameworks involving the entities "color" and "half-past three," half-past three is colorless.
"How many zeros does it take to make a baker's dozen?"
Thirteen (duh).
"How many zeros does it take to make a baker's dozen?"
Thirteen (duh).
Huh, I only counted one. ;)
Quarks, the only allowed causally efficacious entities in the universe, have a lot to answer for. Quarks are causing the US economy to falter, quarks are killing our soldiers in Iraq, quarks are behind communism, nazism, racism, and people who drive too slow in the fast lane. Quarks made me write this obnoxious and inane comment. Damn you, quarks!
I'm curious, Eliezer, do you introduce Bayes into the argument as a means of warrant/justification or do you see it playing a causal (descriptive) role? Historically speaking, for example, the causal reason a telescope was used in your example might be, say, Kuhn's notion of exemplary research ("Galileo did it so it's good enough for me") or some other (perhaps more likely) psychological/cultural explanation and the scientist might be completely disinterested in justifying his belief based on priors (and he might not do such a thing unconsciously either).
On the topic: I think one of the reasons this sort of thing is unnerving to contemplate is the specter of skepticism that tends to still haunt people. Most people believe that if their beliefs do not have some exacting connection with reality (some metaphysical relation) then they can never "reach the world" so to speak. I think this is incorrect. The view that we can never reach the world is predicated on a strong sort of subjectivism; that "inside here" is the privileged starting point of inquiry when, in reality, anything can be our starting point (no point is privileged).
If you reject the infallibility of introspection, it loses its privileged place as the starting point of inquiry, and there's no reason to continue thinking you're bound to it; taking the quantum mechanical view of the world as the starting point for inquiry is no different than taking your subject-bound observations as the starting point for inquiry (and, for that matter, moving from one to the other no longer presents a problem; 3rd person accounts do not need to be justified in terms of 1st person accounts).
It's the looseness of reference that allows us to penetrate beyond our psychology; it's the fact that our words are related to the world by convention that has allowed us to create this elaborate system (science) that establishes a series of conventional relationships between terms that eventually, through a path we can trace and re-trace, takes us to the world.
poke, interesting that you're talking about the middle ground between skepticism and the infallibility of sense data, which is the sort of "defeasible warrant" idea - we DO take our sense data as a starting point (or, as you note, we take a theory as our starting point - though where did the theory come from, ultimately, but somebody's taking his sense data seriously and then interpreting them?) - but if we find a conflict, either among our sense data or between ours and somebody else's, we reduce our trust in our sense data (we don't just toss them out). People are starting to apply this line of thinking not just to straight epistemology but to ethics (and even aesthetics!).
Too much philosophy and spinning around in circular definitions. Eliezer, you cannot transfer experiences, only words which hopefully point our minds to the right thing until we "get it". Layers upon layers of words trying to define reductionism won't make people who haven't "gotten it" yet "get it". It will just lead to increasingly more sophisticated confusion. I suppose the only thing that could snap people into "getting" reductionism at this point is lots of real world examples because that would emulate an experience. How is this useful for building an AGI anyway? Please change your explanation tactic or move on to a different topic(if you want).
Q: Is "snow is white" true? A: No, it is false. Sometimes it is yellow(don't eat it when yellow). Next question.
Our map, then, is very much unlike the territory; our maps are multi-level, the territory is single-level.
We do not know that the territory is single-level. It is conceivable that it is not, and the available evidence does not exclude the possibility.
Can someone just tell us dumb asses the differece between describing something and experiencing it?
we DO take our sense data as a starting point
It may be useful to distinguish between sense data (which can only be observed introspectively) and sensory data (neural activity at the periphery of the nervous system). Our brains do indeed take our sensory data as a starting point of sorts (though not the only starting point - we are not blank slates). However, sense data is a philosophical notion that has been under attack for a long time. Deservedly so, I think. See, for example, J. L. Austin's Sense and Sensibilia, one of the more entertaining and well-written philosophical works IMO.
I prefer to think of the distinction between reality and our models of it not in terms of single-level versus multi-level but rather in terms of the thing itself versus descriptions of the thing: conceptual systems have levels, reality does not.
Thinking in terms of levels is applicable to conceptual systems, but not applicable to reality — applicable to conceptual systems about reality, but not to reality itself.
The notion of level is just a mental construct that is helpful in describing how we think and how we represent. It is a function of how we carve up reality conceptually, but reality itself doesn't contain bones and joints that are waiting to be carved — not even just one fundamental joint that we have no choice about how to carve.
We do not know that the territory is single- level. It is conceivable that it is not, and the available evidence does not exclude the possibility.
The territory is single level...... BY DEFINITION ....... waaaahahahahahahahahahaha !!!!!
Sister Y - I don't think there's any reason to privilege the sensory periphery of our brains over some other part of the situation. We might just as well start with the planet or the telescope as the eyeball peering through the telescope or the brain attached to that eyeball. I don't mean, precisely, that we take theory as a starting point either (or that our observations are always theory-laden); I mean to say we can start from the physical objects themselves as described in our best theories. We can start our inquiry outside of our own brain!
We can do this because we have no privileged knowledge of our brains over and above any other object in the world. If we reject the efficacy of introspection then there is no reason to privilege "the object as I see it" over "the object itself" as the starting point of inquiry. Science knows this. Science makes quantitative measurements; the interesting thing about quantitative measurements is that they work regardless of the details of our psychology. Our brains can represent the world arbitrarily and as long as we agree on a system of measurement we can still make measurements in the world.
Think of measuring length; we make marks along a length of material with arbitrary but equal spacing and as long as my marks match your marks we can talk about lengths. Similarly, our brains can represent those marks anyway they please and as long as my brain uses the same representations as your brain we can still talk about lengths. The same is true of time and, through extension, pressure, temperature, etc, all the way through to the data retrieved from particle accelerators. We can also do (limited) relative comparisons of qualitative data; we can talk about the similarities and dissimilarities of organisms, stellar objects, and so forth.
So I think, in this way, science is unaffected if we reject the efficacy of introspection (including the efficacy of our own sensory data). Since most arguments for the fallibility of science are premised on our sensory periphery having a privileged place in inquiry I also think those arguments are defeated. Whether science remains fallible is another matter entirely. For my own part, I take mathematics to be similar to measurement and the revolution in science due to Kepler and Galileo to be moving directly from measurement to mathematical abstraction, without the previous step of interpretation into a cultural framework (i.e., Aristotelianism). This, I think, leaves science fallible only in the case of human error.
Can someone just tell us dumb asses the differece between describing something and experiencing it?
Um... ok.
Description: If you roll your face on your keyboard you will feel the keys mushing and pressing against your face. The most pronounced features of the tactile experience will be the feeling of the ridges of the keys pressing against your forehead, eyebrows and cheekbones. You will also hear a subtle "thrumping" noise of the keys are being pressed. If you didn't put the cursor in a text editor you might hear some beeps from your computer. Once you lift your head you may still have some residual sensations on your face most likely where the relatively sharp ridges of the keys came in contact with your skin.
Experience: Roll your face on your keyboard. Don't just read this, you have to actually roll your face on the keyboard if you want to experience it. 1, 2, 3, go ... bnkiv7n6ym7n9t675r
Did you notice any difference between the description and the experience?
Anyways, I still hold that you can only define reductionism up to point after which you are just wasting time.
"Anyways, I still hold that you can only define reductionism up to point after which you are just wasting time."
I agree that we might be wasting time. But what do you mean "up to a point"?
The flaw isn't in the idea, but rather in the way we express it. It appears like we're looking for the right analogy. I don't know if that's going to work. But I guess I could try anyway.
I think it might be more like a computer. We don't function at a "machine code" or even an "assembly language" level; rather, it's more like we're a scripting language on the operating system.
Of course, that's imperfect, too.
Constant - I'm not sure I comprehend your distinction (could be lack of caffeine) but thanks for the recommendation.
poke - my friend likes to explain this to his undergrads by asking them how they would verify that a thermometer is accurate (check it against another thermometer, but how do you know that one is accurate . . . etc.) until they figure out that thermometers are only "accurate" according to custom or consensus. Then he asks them how they know their eyes work. And their memories.
Some of them cry.
Okay maybe not really. Anyway, aside from torturing undergrads, I agree that we could just as easily start to do science with "physical objects themselves as described in our best theories" - I just mean that in order to get those theories, we have to believe in our (or someone else's) perceptions, memory, ability to do logic, etc. Ultimately I don't think it's a problem, at least one serious enough to destroy science.
Also there's this cute little move from Warren Quinn where he asserts that no philosophical theory could ever convince him that his chair wasn't there, no matter how sound and careful the argument - because his sureness of his perceptions would outweigh any sureness he could possibly feel in any theory.
Any lit recommendations from poke?
Edit: Now I see Sister_Y addressed my point in the very next paragraph, so this entire comment is a reading comprehension fail more than anything.
Necroing:
poke - my friend likes to explain this to his undergrads by asking them how they would verify that a thermometer is accurate (check it against another thermometer, but how do you know that one is accurate . . . etc.) until they figure out that thermometers are only "accurate" according to custom or consensus. Then he asks them how they know their eyes work. And their memories.
Some of them cry.
Go to the beach, light a fire, boil some water. Put the thermometer in the boiled water - does it show 100 degrees Celsius? Still at sea level, put a cup of water in a fridge untill it starts freezing. Put the thermometer in the cup - does it show 0 degrees Celsius?
If yes to both, you have a working thermometer. This way, you don't rely on the consensus of other thermometers. As for the custom of calling a working thermometer accurate - that's what it is for.
Eyes and memory can be similarly tested.
Of course, accepting the results of such tests requires acceptance of induction from the past. Maybe the realization you've faced "Last Thursdayism" for the first time at undergraduate level is something to cry about, but no one actually does.
Lest I sound too smug, rest assured I am not convinced I would've done better before finding Less Wrong.
How do you know that water always boils at the same temperature? Well, you could use a reliable thermometer...
The moral of the story is not so much that science always works, it's that it works in a way that's more coherentist than foundationalist. And the downside of coherentism is that you can have more than one equally coherent wordlviews...
How do you know that water always boils at the same temperature?
I remember reading it somewhere...
I see your point. But if water didn't always boil at the same temperature, why would we bother inventing thermometers?
The moral of the story is not so much that science always works, it's that it works in a way that's more coherentist than foundationalist.
Right. And since science does work, coherentism gets a big boost in probability, right until the sun stop rising every day.
And the downside of coherentism is that you can have more than one equally coherent wordlviews...
But would they work equally well? We value science primarily for giving us results, not for being coherent.
If both views are equally coherent and give us equal result (or the results are unclear as of yet), choosing one would be privileging the hipotesis.
I see your point. But if water didn’t always boil at the same temperature, why would we bother inventing thermometers?
We have more need to measure the unpredictable than the predictable.
If both views are equally coherent and give us equal result (or the results are unclear as of yet), choosing one would be privileging the hipotesis.
Not every one sees things that way. The more hardline claims require the physical map to exclude others.
I see your point. But if water didn’t always boil at the same temperature, why would we bother inventing thermometers?
We have more need to measure the unpredictable than the predictable.
If there was nothing with constant temperature, thermometers would work very differently. My first instinct was to say they wouldn't work at all. But then I remembered the entire field of economics, so your point stands.
Not every one sees things that way. The more hardline claims require the physical map to exclude others.
Good luck with that. I couldn't calculate the behaviour of the quarks in a single hydrogen atom if my life depended on it.
Your reliable thermometer doesn't need to be well-calibrated - it only has to show the same value whenever it's used to measure boiling water, regardless of what that value is. So the dependence isn't quite so circular, thankfully.
You are saying it doesn't need to be accurate. To show that boiling water is always the same temperature, the thermometer doesn't need to display the rest that temperature ...any consistent temperature will do ...but it does need to avoid varying randomly, and that is reliability
"We do not know that the territory is single-level. It is conceivable that it is not, and the available evidence does not exclude the possibility."
The available evidence does not support the possibility either. Lack of evidence actually is a form of evidence...for the opposing argument. http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_of_absence/
"Just: There are patterns that exist in reality where we see "hands", and these patterns have something in common, but they are not fundamental."
Reality is the space in which we observe trends that either bear out or contradict our beliefs. Reality seems to bear out a pattern corresponding with hands. Hands, then, correspond to something true about reality (even if it is just probably true, the probability is a true statement of something real.) We are not privy to the knowledge of how many removes we are away from the true experience of hands, but it isn't clear how one could convincingly argue the non-existence of a hand-like pattern OR that the bottom level of the territory corresponding to hands is more complex than the map we represent them on.
Otherwise stated: I cannot exclude the idea of the Bible being an exact account of creation. I can, however, disregard it in light of the overwhelming evidence to the contrary. If I do not disregard it then I must consider it on equal grounds with all "accounts" of creation and concede the utter impossibility of making a decision. To me, it is not clear how a human brain could be capable of granting equal weight of truth to mutually exclusive possibilities without a bit of cognitive dissonance or intellectual dishonesty.
So when something is not excluded by the evidence, you may either a.) acknowledge the high degree of probability that the unsupported claim is false (rationality); b.) disregard the evidence and believe in it anyway (irrationality); c.) see who can make the most unintentionally ironic assertion about the lacunae in the evidence holding more weight than the evidence itself (arationality.)
I don't see any likelihood for the existence of evidence of reality contradicting itself (thereby becoming non-reality.) I can't even fathom what form that evidence might take. Therefore I call reality objective and work within it as if it were. I'm open to the possibility of this not being true, but a person telling me "it might not be true" is not enough to forestall my effort at evaluating the trends I seem to see.
tpckac: "We do not know that the territory is single-level. It is conceivable that it is not, and the available evidence does not exclude the possibility."
ENC: "The available evidence does not support the possibility either. Lack of evidence actually is a form of evidence...for the opposing argument. http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_of_absence/"
Cool! A one-level territory beats a multi-level territory due to lack of evidence. Now all we need is some evidence that there is a one-level territory, rather than no territory at all ("maps all the way down").
It sure seems to me that the notion of territory is just not carrying any weight here. I can determine the truth of "snow is white" directly at the level where "snow" has a simple non-reductive meaning by simply looking at lots of snow. Or I can be a reductionist and examine crystals of H2O with spectroscopic equipment. I could do that even before anybody had even heard of quarks. And we will still be able to do it three centuries from now when the standard model has been replaced by superstrings or whatever. I just don't need territory. I can be just as reductionist as I like using maps.
And even if we had a Theory of Everything in hand, how have we gained anything by calling the lowest-level map "The Territory"? Or is it that "territory" represents The One Shared Reality, whereas maps are inside people's minds - we have 6 billion of them floating around. Cuz if maps are (objective) mathematical objects with (objective) platonic existences of their own, I don't really see the need for a Territory - how is it different from a map?
"If I do not disregard it then I must consider it on equal grounds with all "accounts" of creation and concede the utter impossibility of making a decision."
"stupid postmodernists" would suggest a separate solution. Namely - the bible presents an account of creation which is "true" w/r/t certain cultural contexts.
Now, all "truth" in this sense is "equivalent" in that it is merely statements within a cultural or philosophical context. However, this is not the standard by which you, I, or anyone (since we are all necessarily IN a cultural/philosophical context) judge truth.
So you are free to say "I disregard the bible as an accurate account of creation because I belong to a cultural context in which it is incoherent, but I accept that it presents 'truth' in various contexts in which it (or its interpretation) does not contain inconsistencies."
See, the issue is that "truth" to you can never be "truth" to me. You can merely send signals. Like your blog post, for instance. Since we probably largely share contexts you have high probability of transmitting truth. Good job! Of course, your usual mode of communication won't work to convince people with different standards.
Now it comes down to whether you want to call your "truth" the REAL Truth. You can do it if you want. It might even make you feel better. Just know that everyone else (even people who disagree with you) is doing it too.
Oh well, another bit of nothing sent into the void.
If two people were sufficiently motivated, they'd rapidly agree on what exactly "REAL Truth" is.
Consider the telescope. Why did people trust telescopes? Probably because they learned to first trust spy glasses. It was pretty easy to trust that in fact there really was a group of brigands riding across that field towards us ...
Regarding reductionism and quarks-- Recently physicists have become more interested in 'complexity'. From Physics World survey Dec. 1999-
"Reductionism has failed in a grandiose manner," Itamar Procaccia Giorgio Margaritondo, (the challenge for physics is) "... to develop a general theory of complex systems, in particular of living systems, without relying on the 'reductionist' approach, which is based on the illusion that complex systems can be explained based on an understanding of their more elementary components."
I mention this because sometimes people think that the reductionist appproach is argued on philosophic grounds only.
Eliezer: no comment on my point that 'single-levelness' is an attribute of your model of reality rather than of reality itself? And that saying "reality is single-level" is therefore misleading.
Indeed, what would it mean for reality to be multi-leveled? (This would address tcpkac's comment too.)
PK: I think the person's question around experience and description might have been asking about reductionism vs. holism.
I thought flaming was for the MMORPG boards?
Ta ta!
"there is no spoon" is only true iff there is no spoon.
Reality is just quarks, the "spoon" is only a useful heuristic I have in my head to model a particular configuration of quarks... ie, the "spoon" is only in the model in my head... therefore there is a "spoon", but no spoon.
...and yet, the quarks that I point at,when I say "spoon" definitely exist.
so - is there a spoon?
I really hope the straw-postmodernists don't show up in the eventual book digested from the sequences.
I don't know if you can distinguish straw-postmodernists from postmodernists. I certainly can't, and I know several postmodernists. Mechanism or Art, really...
/me adds to personal homework list: something on uses for postmodernism. The uses I'm thinking of are for cultural interaction with other humans. Prerequisites: nailing it down to the degree I would if I'd actually studied it closely rather than picking it up as I went along. Useful: non-stupid academic postmodernists I know. ETA: whenever.
Highly thought provoking post. Thanks a lot as always EY. Here's what I got provoked.
"There are socks on my feet." means "a bunch of fundamental quanta arranged sock-wise surround the two groups of fundamental quanta arranged foot-wise, that causally interacts via a bunch of quanta arranged nerve-wise, with the bunch of quanta arranged brain-wise with average spatial center x y z." where (x,y,z) is the average center coordinate of my brain. "All snow is white." means "If you arrange a group of fundamental quanta snow-wise, then that group must also be arranged white wise." "Shoes are not fundamental." means "One fundamental quanta cannot be arranged shoe-wise." "Electrons are fundamental." means "You can arrange one fundamental quanta electron wise." And probably most importantly, "Shoes don't exist." means "there is no group of fundamental quanta in the universe that is arranged shoe-wise." So, clearly, "Shoes are not fundamental" does not imply "Shoes don't exist." I get the feeling that if more ant-reductionists didn't think that they could substitute "non-existent", for "non-fundamental" much of the uncomfort they experience with the reductionist thesis would go away.
The problem I come to is figuring out how it is that we tell the difference between quanta arranged x wise, and quanta not arranged x wise. I also presume that for at least some categories, such as hand, a given group of quanta are not simply arranged hand wise or not hand wise, some sets of quanta are arranged more hand wise than others.
Thing space might help determine the actual categories of the empirical world, but I'm not sure it can help us with understanding how neural networks sort particulars. At best it can help us with how they would if they were the best scientists they could be. But if you show that there is some way to tell given a group of quanta that is arranged categorical-neural-network-wise hooked up to quanta arranged sensing apparatus wise, and given another unspecified group of quanta within the range of the sensing apparatus, to what degree that unspecified group triggers the neural network, all in terms of the relative properties of the fundamental quanta involved, you provide a proof of existence for an algorithm that sorts all quanta groups into any neurally definable category.
This lets us make some sort of super empirical syllogism:
(1):If a quanta group triggers the categorical neural network A, x amount, then it also triggers the categorical neural network B, y amount. (2):If a quanta group triggers the categorical neural network B, y amount, then it also triggers the neural category C, z amount. (c):If a quanta group triggers the neural network A, x amount, then it triggers the neural network C, z amount.
Where a quanta group is a complete specification of all the quanta involved and all of their relative positions over a time interval. We can say that 1 is as much as a neural category can be triggered by a quanta group, and 0 is as little as it can be triggered. So given that "if a quanta group triggers neural category A, x amount, then it also triggers neural category B, (1 - x) amount" we say that B is the compliment of A. The thing is that this theory of category only works for one agent at a time, not the entirety of a linguistic community. My categorical network for "dog" is probably very different from yours on the level of neurons, never-mind the level of fundamental quanta, but they are activated to very similar degrees by identical quanta groups. There is some objective amount of expected error in approximating the degree of activation of my "dog" category using yours, but it can't be too much since we still manage to communicate effectively about dogs.
I'm sure I have something more to say about all this, but I have HW. Maybe I'll write a post later after I've collected my thoughts a bit more if this comment goes over well.
Something that helps me understand reductionism is defining "hands" not as a set of quarks in some state, but as a range of possible sets of quarks in a range of possible states. Replace quarks by whatever fundamental thing reality is made of.
Replace quarks by whatever fundamental thing reality is made of.
That's the kicker, isn't it. We'd like to be able to look at an arbitrary model of the world, and see if it has any observers in it who might experience "hands".
The reductionist thesis (as I formulate it) is that human minds, for reasons of efficiency, use a multi-level map in which we separately think about things like "atoms" and "quarks", "hands" and "fingers", or "heat" and "kinetic energy". Reality itself, on the other hand, is single-level in the sense that it does not seem to contain atoms as separate, additional, causally efficacious entities over and above quarks.
Sadi Carnot formulated the (precursor to) the second law of thermodynamics using the caloric theory of heat, in which heat was just a fluid that flowed from hot things to cold things, produced by fire, making gases expand—the effects of heat were studied separately from the science of kinetics, considerably before the reduction took place. If you're trying to design a steam engine, the effects of all those tiny vibrations and collisions which we name "heat" can be summarized into a much simpler description than the full quantum mechanics of the quarks. Humans compute efficiently, thinking of only significant effects on goal-relevant quantities.
But reality itself does seem to use the full quantum mechanics of the quarks. I once met a fellow who thought that if you used General Relativity to compute a low-velocity problem, like an artillery shell, GR would give you the wrong answer—not just a slow answer, but an experimentally wrong answer—because at low velocities, artillery shells are governed by Newtonian mechanics, not GR. This is exactly how physics does not work. Reality just seems to go on crunching through General Relativity, even when it only makes a difference at the fourteenth decimal place, which a human would regard as a huge waste of computing power. Physics does it with brute force. No one has ever caught physics simplifying its calculations—or if someone did catch it, the Matrix Lords erased the memory afterward.
Our map, then, is very much unlike the territory; our maps are multi-level, the territory is single-level. Since the representation is so incredibly unlike the referent, in what sense can a belief like "I am wearing socks" be called true, when in reality itself, there are only quarks?
In case you've forgotten what the word "true" means, the classic definition was given by Alfred Tarski:
The statement "snow is white" is true if and only if snow is white.
In case you've forgotten what the difference is between the statement "I believe 'snow is white'" and "'Snow is white' is true", see here. Truth can't be evaluated just by looking inside your own head—if you want to know, for example, whether "the morning star = the evening star", you need a telescope; it's not enough just to look at the beliefs themselves.
This is the point missed by the postmodernist folks screaming, "But how do you know your beliefs are true?" When you do an experiment, you actually are going outside your own head. You're engaging in a complex interaction whose outcome is causally determined by the thing you're reasoning about, not just your beliefs about it. I once defined "reality" as follows:
Even when I have a simple hypothesis, strongly supported by all the evidence I know, sometimes I'm still surprised. So I need different names for the thingies that determine my predictions and the thingy that determines my experimental results. I call the former thingies 'belief', and the latter thingy 'reality'."
The interpretation of your experiment still depends on your prior beliefs. I'm not going to talk, for the moment, about Where Priors Come From, because that is not the subject of this blog post. My point is that truth refers to an ideal comparison between a belief and reality. Because we understand that planets are distinct from beliefs about planets, we can design an experiment to test whether the belief "the morning star and the evening star are the same planet" is true. This experiment will involve telescopes, not just introspection, because we understand that "truth" involves comparing an internal belief to an external fact; so we use an instrument, the telescope, whose perceived behavior we believe to depend on the external fact of the planet.
Believing that the telescope helps us evaluate the "truth" of "morning star = evening star", relies on our prior beliefs about the telescope interacting with the planet. Again, I'm not going to address that in this particular blog post, except to quote one of my favorite Raymond Smullyan lines: "If the more sophisticated reader objects to this statement on the grounds of its being a mere tautology, then please at least give the statement credit for not being inconsistent." Similarly, I don't see the use of a telescope as circular logic, but as reflective coherence; for every systematic way of arriving at truth, there ought to be a rational explanation for how it works.
The question on the table is what it means for "snow is white" to be true, when, in reality, there are just quarks.
There's a certain pattern of neural connections making up your beliefs about "snow" and "whiteness"—we believe this, but we do not know, and cannot concretely visualize, the actual neural connections. Which are, themselves, embodied in a pattern of quarks even less known. Out there in the world, there are water molecules whose temperature is low enough that they have arranged themselves in tiled repeating patterns; they look nothing like the tangles of neurons. In what sense, comparing one (ever-fluctuating) pattern of quarks to the other, is the belief "snow is white" true?
Obviously, neither I nor anyone else can offer an Ideal Quark Comparer Function that accepts a quark-level description of a neurally embodied belief (including the surrounding brain) and a quark-level description of a snowflake (and the surrounding laws of optics), and outputs "true" or "false" over "snow is white". And who says the fundamental level is really about particle fields?
On the other hand, throwing out all beliefs because they aren't written as gigantic unmanageable specifications about quarks we can't even see... doesn't seem like a very prudent idea. Not the best way to optimize our goals.
It seems to me that a word like "snow" or "white" can be taken as a kind of promissory note—not a known specification of exactly which physical quark configurations count as "snow", but, nonetheless, there are things you call snow and things you don't call snow, and even if you got a few items wrong (like plastic snow), an Ideal Omniscient Science Interpreter would see a tight cluster in the center and redraw the boundary to have a simpler definition.
In a single-layer universe whose bottom layer is unknown, or uncertain, or just too large to talk about, the concepts in a multi-layer mind can be said to represent a kind of promissory note—we don't know what they correspond to, out there. But it seems to us that we can distinguish positive from negative cases, in a predictively productive way, so we think—perhaps in a fully general sense—that there is some difference of quarks, some difference of configurations at the fundamental level, which explains the differences that feed into our senses, and ultimately result in our saying "snow" or "not snow".
I see this white stuff, and it is the same on several occasions, so I hypothesize a stable latent cause in the environment—I give it the name "snow"; "snow" is then a promissory note referring to a believed-in simple boundary that could be drawn around the unseen causes of my experience.
Hilary Putnam's "Twin Earth" thought experiment, where water is not H20 but some strange other substance denoted XYZ, otherwise behaving much like water, and the subsequent philosophical debate, helps to highlight this issue. "Snow" doesn't have a logical definition known to us—it's more like an empirically determined pointer to a logical definition. This is true even if you believe that snow is ice crystals is low-temperature tiled water molecules. The water molecules are made of quarks. What if quarks turn out to be made of something else? What is a snowflake, then? You don't know—but it's still a snowflake, not a fire hydrant.
And of course, these very paragraphs I have just written, are likewise far above the level of quarks. "Sensing white stuff, visually categorizing it, and thinking 'snow' or 'not snow'"—this is also talking very far above the quarks. So my meta-beliefs are also promissory notes, for things that an Ideal Omniscient Science Interpreter might know about which configurations of the quarks (or whatever) making up my brain, correspond to "believing 'snow is white'".
But then, the entire grasp that we have upon reality, is made up of promissory notes of this kind. So, rather than calling it circular, I prefer to call it self-consistent.
This can be a bit unnerving—maintaining a precarious epistemic perch, in both object-level beliefs and reflection, far above a huge unknown underlying fundamental reality, and hoping one doesn't fall off.
On reflection, though, it's hard to see how things could be any other way.
So at the end of the day, the statement "reality does not contain hands as fundamental, additional, separate causal entities, over and above quarks" is not the same statement as "hands do not exist" or "I don't have any hands". There are no fundamental hands; hands are made of fingers, palm, and thumb, which in turn are made of muscle and bone, all the way down to elementary particle fields, which are the fundamental causal entities, so far as we currently know.
This is not the same as saying, "there are no 'hands'." It is not the same as saying, "the word 'hands' is a promissory note that will never be paid, because there is no empirical cluster that corresponds to it"; or "the 'hands' note will never be paid, because it is logically impossible to reconcile its supposed characteristics"; or "the statement 'humans have hands' refers to a sensible state of affairs, but reality is not in that state".
Just: There are patterns that exist in reality where we see "hands", and these patterns have something in common, but they are not fundamental.
If I really had no hands—if reality suddenly transitioned to be in a state that we would describe as "Eliezer has no hands"—reality would shortly thereafter correspond to a state we would describe as "Eliezer screams as blood jets out of his wrist stumps".
And this is true, even though the above paragraph hasn't specified any quark positions.
The previous sentence is likewise meta-true.
The map is multilevel, the territory is single-level. This doesn't mean that the higher levels "don't exist", like looking in your garage for a dragon and finding nothing there, or like seeing a mirage in the desert and forming an expectation of drinkable water when there is nothing to drink. The higher levels of your map are not false, without referent; they have referents in the single level of physics. It's not that the wings of an airplane unexist—then the airplane would drop out of the sky. The "wings of an airplane" exist explicitly in an engineer's multilevel model of an airplane, and the wings of an airplane exist implicitly in the quantum physics of the real airplane. Implicit existence is not the same as nonexistence. The exact description of this implicitness is not known to us—is not explicitly represented in our map. But this does not prevent our map from working, or even prevent it from being true.
Though it is a bit unnerving to contemplate that every single concept and belief in your brain, including these meta-concepts about how your brain works and why you can form accurate beliefs, are perched orders and orders of magnitude above reality...