How do we know dreams aren't real?
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134
The question at the end seems like it presupposes that there's some invisible baton that gets passed around between different copies of you.
When you go to sleep you imagine the baton being passed from your sleeping self to a copy who's having the same experiences elsewhere in the (hypothetically infinite) universe. And then you ask "But what if that copy forgets to pass the baton back to me when I wake up?"
But of course, there is no baton. This should be reassuring, because if there's no baton, the baton can't get lost or misplaced :D You wake up as yourself not because every night the baton manages to make its way back to you, you just wake up and the baton doesn't exit.
1Even if there is no baton, I care about future versions of myself (idk why, humans are weird I guess). Is your proposal that I only care about future versions of myself when I'm awake?
"there is no baton" is fundamental to the question. If there was a baton, we could empirically observe a rule like "the baton is only passed to states that are spatiotemporally nearby". But if there is no baton, the induction:
present waking me --(cares about)--> future dreaming me ==(is identical to)== a waking person who has the same conscious expe...
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You can care about what you want. For me, I do rate the continuations that preserve my awake self as more me.
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Dreams have features that make them different than reality. If you for example look at a clock two times in a dream the clock does not behave the way clocks in real life tend to behave. A clock in real life has object permanence and keeps it's state in a way that a dream clock usually doesn't.
People who train lucid dreaming have a variety of tests like that for telling the dreaming state apart from the normal reality.
Object permanence where objects are able to exist independent from you looking at them is a key feature of physical reality and a world like the dream world that does not have that clearly is not physical reality.
This is probably the best answer, but I feel like there are still plenty of dreaming states that are not immediately distinguishable from waking states.
In particular Object Permanence is not something we get to test if we restrict ourselves to conscious "moments", since "I will wait 1 second and see if the object in front of me is still there" would mean you have translated to a different conscious state.
Using lucid dreaming as a counterexample doesn't seem to affect the argument, since the argument is some dreaming states might also be the waking states, ...
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How do you define ‘real’, ‘me’, ‘real me’, etc…?
This seems to be stemming from some internal confusion.
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Just because you don't notice when you're dreaming, doesn't mean that dream experiences could just as well be waking experiences. The map is not the territory; Mach's principle is about phenomena that can't be told apart, not just anything you happen not to notice the differences between.
When I was recovering from a psychotic break in 2013, I remember hearing the beeping of a crosswalk signal, and thinking that it sounded like some sort of medical monitor, and wondering briefly if I was actually on my deathbed in a hospital, interpreting the monitor sound as a crosswalk signal and only imagining that I was healthy and outdoors—or perhaps, both at once: the two versions of reality being compatible with my experiences and therefore equally real. In retrospect, it seems clear that the crosswalk signal was real and the hospital idea was just a delusion: a world where people have delusions sometimes is more parsimonious than a world where people's experiences sometimes reflect multiple alternative realities (exactly when they would be said to be experiencing delusions in at least one of those realities).
My argument is "an infinite universe where everything that is logically possible happens" is more parsimonious than "a universe where only 'normal' things happen"
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To run with the spirit of your question:
Assuming the Dust Theory is true (i.e. the continuity of our experience is maintained purely by there somewhere being the next state of the state-machine-which-is-us). It doesn't need to be causally connected to your current state. So far so good.
What if there is more than one such subsequent state in the universe? No problem so far. Our measure just splits, and we roll the dice on where we'll find ourselves (it's a meaningless question to ask if the split happens at the moment of the spatial, or the computational divergence).
But what if something steals our measure this way? What if, while sleeping, our sleeping state is instantiated somewhere else (thereby stealing 50% of our measure) and never reconnects to the main computational stream instantiated in our brain (so every time we dream, we toss a coin to jump somewhere else and never come back)?
One obvious solution is to say that our sleeping self isn't us. It's another person whose memories are dumped into our brain upon awakening. This goes well with our sleeping self acting differently than us and often having entirely different memories. In that case, there is no measure stealing going on, because the sleeping stream of consciousness happening in our brain isn't ours.
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https://space.mit.edu/home/tegmark/crazy.html Large universes put some subtleties into the meaning of "real" that aren't present in its common usage.
Decision theory-wise, caring about versions of yourself that are inexorably about to dissolve into thermal noise doesn't seem useful. As a more general principle, caring about the decisions you make seems useful to the extent that those decisions can predictably change things.
My dreams have none of the consistency that allowed smart people to figure out the laws of nature over the millenia. It might be possible for a superintelligence to figure out how to make decisions within a world working on dream rules which had predictable future effects, but I believe it to be far beyond my powers.
"I only care about conscious states where smart people are doing physics" has to be the most LessWrong take possible.
This feels like you are, on some level, not thinking of consciousness as a thing that is fully and actually made of atoms. Instead talking about it like an immaterial soul that happens to currently be floating around in the vicinity of a particular set of atoms—but could in theory float off elsewhere to some other set of atoms that happens to be momentarily be arranged into a pattern that's similar enough to confuse the consciousness into attaching itself to to a different body.
In an atoms-first view of the world (where you have a brain made of physical stuff arranged a particular way such that it performs various conscious actions), I don't see a way to conceive of that consciousness ever relocating to a different brain; any more than you can relocate your digestion to a different stomach (even if someone else happens to have eaten all the same meals recently to make their gut contents exactly the same as yours).
2If you think consciousness can't be relocated, you presumably also think that teleportation would only create copies while destroying the originals. You might then be hesitant to use teleportation.
You might even think that consciousness can't be relocated into the future, insofar physical stuff of current brains will be different in future brains. Or you might argue that consciousness can be relocated into the future, namely when the physical stuff is transformed continuously in space-time, and you argue that relocation of consciousness is possible under and only under such continuous physical transformation.
1you presumably also think that teleportation would only create copies while destroying the originals. You might then be hesitant to use teleportation.
As an aside, Holden's view of identity makes him unconcerned about this question, and I've gradually gotten round to it as well.
I'm skeptical that continuity of personal identity is actually real, beyond a social consensus and a deeply held evolved instinct. I don't expect there are metaphysical markers that strictly delineate which person-moments are part of "the same" ongoing person through time. So hypothetical new scenarios like teleportation, brain emulation, clones built from brain scans (etc) are indeed challenging—they break apart things that have previously always gone together as a bundle.
Even so, physical continuity of the brain involved seems like a reasonable basis for that consensus. Or at very least some kind of casual connection between one person-moment and the next. Whereas "by pure blind chance I briefly occupied the same mental state as someone outside my light cone" still just seems confused.
There are several arguments for psychological continuity over time (involving memories and personality traits) rather than physical continuity. E.g. teleportation (already John Locke made basically the teleportation argument except with resurrection in heaven) and cases like dissociative identity disorder or similar pathological cases where physical continuity seems largely maintained while personal identity arguably isn't. There are also hypothetical cases: If consciousness wasn't tied to atoms, and body swap like in fiction was possible, we would still call it "a person swapping bodies" instead of "a person swapping minds". Though Boltzmann brains seem to be an argument in favor of physical continuity.
I think you're using the word "real" in a confusing way. The possibility/likelihood that there are things outside your light cone or possible causal web is completely irrelevant to any experiences you have had or will ever have.
Dreams are "real", in that the dream is a thing which has an impact on your memories and perceptions. Events and specifics in dreams are "unreal", in that they have no predictive power nor causal effect on waking experiences.
Likewise your imagining/predicting things in alternate universes (or this universe outside your lightcone) - your beliefs are real, in that they impact your perceptions and actions. The specific instantiations are "unreal" because they have no causal impact on anything in the real world.
Your # 2 sounds like an argument not-infrequently made by proponents of computationalism, which is quite a commonly-held position here on LessWrong. Not sure if it exactly matches but you might enjoy their positions in any case.
the universe is infinite in the sense that every possible combination of atoms is repeated an infinite number of times (either because the negative curvature of the universe implies the universe is unbounded or because of MWI)
As a side note, I do not like seeing these two possible causes of this belief be put in the same bucket. I think they are quite different in an important respect: while it seems MWI would indeed imply this conclusion, negative curvature alone certainly would not. A universe that is unbounded in size can certainly be bounded in a lot of other respects, and there is no particularly persuasive reason to think that "every possible combination of atoms is repeated an infinite number of times."
After all, the set of all integers is unbounded and infinite, but this does not imply that every real number occurs inside of it.
However, flat/negative curvature plus the size of the universe being infinite and the cosmological principle, which basically states that the universe lacks a preferred direction and location would imply the conclusion, as it would mean our collection of atoms isn't special at all, and this goes for any finite portion of the universe.
No, I don't think that alone would do it, either.
As a basic counterexample, just consider a fully empty infinite universe. It is in equilibrium (and does not violate any known laws of physics), it has an infinite size, and it adheres to the cosmological principle (because every single region is just as empty as any other region). And yet, it quite obviously does not contain every possible configuration of atoms that the laws of physics would allow...[1]
Or a universe that just has copies of the same non-empty local structure, repeated in an evenly-spaced grid. From the perspective of any of the local structures, the universe looks the same in every direction. But the collection of possible states is confined to be finite by the repeated tiling pattern.
- ^
Unless we use a definition of "possible" that just collapses into tautology due to macro-scale determinism...
1As a basic counterexample, just consider a fully empty infinite universe. It is in equilibrium (and does not violate any known laws of physics)
Your premise violates quantum mechanic, actually. Such an universe's amplitude distribution is delta function (fully empty with probability 1, any other state with probability 0), which does not have second derivative so its future evolution is undefined.
Actually, collections of atoms (let's call them structures) can be special.
For instance, there are structures which tend to produce copies of themselves; with some changes (one sign flip), one can obtain structure which tends to destroy its instances. They have approximately same complexity so their rate of randomly arising is equal; however, over time count of former structures increases while count of latter decreases. So we shouldn't expect all atom collections to appear with equal probability even in full universe.
After all, the set of all integers is unbounded and infinite, but this does not imply that every real number occurs inside of it.
This is because Z:
1. Isn't random
2. is uncountably smaller than R
Saying every finite combination of atoms exists an infinite number of times in an unbounded universe is more like saying every finite sequence of digits exists an infinite number of times in the digits of pi.
This is because Z:
1. Isn't random2. is uncountably smaller than R
This is imprecise. It is more useful to say that it happens because we literally have .
Indeed, randomness and countability have little to do with this situation. Consider , where B is a random set of nonzero rational numbers such that . Then S is a random set (i.e., a set-valued random variable) that is not uncountably smaller than (the difference between and S is included in the countable set ), and yet we know for sure that not all real numbers are in S (because, for example, 0 cannot be an element of S).
Saying every finite combination of atoms exists an infinite number of times in an unbounded universe is more like saying every finite sequence of digits exists an infinite number of times in the digits of pi.
Note that the last property (aka, the idea that pi is normal) is not something that has been proven. So if you are trying to use the notion that it has to be true in an analogy with the idea that "every finite combination of atoms exists an infinite number of times in an unbounded universe" must also be true, this would not be a sound argument.
In light of this particular example, I also don't really understand why you focused on randomness in your previous comment. After all, pi is not a "random" number under the most natural meaning of that term; it and its digits are fully deterministic.
Indeed, randomness and countability have little to do with this situation.
No, Z literally cannot contain R because R>Z. On the other had, we know that the universe is made up of atoms and that many finite arrangements of atoms can be found in the universe.
Note that the last property (aka, the idea that pi is normal) is not something that has been proven. So if you are trying to use the notion that it has to be true in an analogy with the idea that "every finite combination of atoms exists an infinite number of times in an unbounded universe" must also be true, this would not be a sound argument.
You maybe confusing "sound" with "proven". Most mathematicians believe pi is normal, so assuming this is a perfectly reasonably assumption to make when reasoning even if the conclusions of that reasoning won't have the rigor of mathematical proof.
No, Z literally cannot contain R because R>Z.
I don't see what this has do to with randomness or countability? You are the one who brought those two notions up, and that part my response only meant to deal with them.
You maybe confusing "sound" with "proven".
No, I am using "sound" in the standard philosophical sense as meaning an argument that is both valid and has true premises, which we do not know holds here because we do not know that the premise is correct.
In philosophy it is perfectly normal to use arguments that are merely "likely" to be true (as opposed to mathematically proven)
Right, but such an argument would not be "sound" from a theoretical logical perspective (according to the definition I mentioned in my previous comment), which is the only point I meant to get across earlier.
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