A few months ago, Rob Bensinger made a rather long post (that even got curated) in which he expressed his views on several questions related to personal identity and anticipated experiences in the context of potential uploading and emulation. A critical implicit assumption behind the exposition and reasoning he offered was the adoption of what I have described as the "standard LW-computationalist frame." In response to me highlighting this, Ruben Bloom said the following:
I differ from Rob in that I do think his piece should have flagged the assumption of ~computationalism, but think the assumption is reasonable enough to not have argued for in this piece.
I do think it is interesting philosophical discussion to hash it out, for the sake of rigor and really pushing for clarity. I'm sad that I don't think I could dive in deep on the topic right now.
However, as I pointed out in that thread, the lack of argumentation or discussion of this particular assumption throughout the history of the site means it's highly questionable to say that assuming it is "reasonable enough":
As TAG has written a number of times, the computationalist thesis seems not to have been convincingly (or even concretely) argued for in any LessWrong post or sequence (including Eliezer's Sequences).
TAG himself made a similar and important point in a different comment on the same post:
Naturalism and reductionism are not sufficient to rigourously prove either form of computationalism -- that performing a certain class of computations is sufficient to be conscious in general, or that performing a specific one is sufficient to be a particular conscious individual.
This has been going on for years: most rationalists believe in computationalism, none have a really good reason to.
Arguing down Cartesian dualism (the thing rationalists always do) doesn't increase the probability of computationalism, because there are further possibilities , including physicalism-without-computationalism (the one rationalists keep overlooking) , and scepticism about consciousness/identity.
One can of course adopt a belief in computationalism, or something else, in the basis of intuitions or probabilities. But then one is very much in the ream of Modest Epistemology, and needs to behave accordingly.
"My issue is not with your conclusion, it’s precisely with your absolute certainty, which imo you support with cyclical argumentation based on weak premises".
And, indeed (ironically enough), in response to andesoldes's excellent distillation of Rob's position and subsequent detailed and concrete explanation of why it seems wrong to have this degree of confidence in his beliefs, Bensinger yet again replied in a manner that seemed to indicate he thought he was arguing against a dualist who thought there was a little ghost inside the machine, an invisible homunculus that violated physicalism:
I agree that "I made a non-destructive software copy of myself and then experienced the future of my physical self rather than the future of my digital copy" is nonzero Bayesian evidence that physical brains have a Cartesian Soul that is responsible for the brain's phenomenal consciousness; the Cartesian Soul hypothesis does predict that data. But the prior probability of Cartesian Souls is low enough that I don't think it should matter.
You need some prior reason to believe in this Soul in the first place; the same as if you flipped a coin, it came up heads, and you said "aha, this is perfectly predicted by the existence of an invisible leprechaun who wanted that coin to come up heads!". Losing a coinflip isn't a surprising enough outcome to overcome the prior against invisible leprechauns.
But, as andesoldes later ably pointed out:
You're missing the bigger picture and pattern-matching in the wrong direction. I am not saying the above because I have a need to preserve my "soul" due to misguided intuitions. On the contrary, the reason for my disagreement is that I believe you are not staring into the abyss of physicalism hard enough. When I said I'm agnostic in my previous comment, I said it because physics and empiricism lead me to consider reality as more "unfamiliar" than you do (assuming that my model of your beliefs is accurate). From my perspective, your post and your conclusions are written with an unwarranted degree of certainty, because imo your conception of physics and physicalism is too limited. Your post makes it seem like your conclusions are obvious because "physics" makes them the only option, but they are actually a product of implicit and unacknowledged philosophical assumptions, which (imo) you inherited from intuitions based on classical physics.
More specifically, as I wrote in response to Seth Herd, "[the] standard LW-computationalist frame reads to me as substantively anti-physicalist and mostly unreasonable to believe in" for reasons I gave in my explanation to Bloom:
What has been argued for, over and over again, is physicalism, and then more and more rejections of dualist conceptions of souls.
That's perfectly fine, but "souls don't exist and thus consciousness and identity must function on top of a physical substrate" is very different from "the identity of a being is given by the abstract classical computation performed by a particular (and reified) subset of the brain's electronic circuit," and the latter has never been given compelling explanations or evidence. [1] This is despite the fact that the particular conclusions that have become part of the ethos of LW about stuff like brain emulation, cryonics etc are necessarily reliant on the latter, not the former.
As a general matter, accepting physicalism as correct would naturally lead one to the conclusion that what runs on top of the physical substrate works on the basis of... what is physically there (which, to the best of our current understanding, can be represented through Quantum Mechanical probability amplitudes), not what conclusions you draw from a mathematical model that abstracts away quantum randomness in favor of a classical picture, the entire brain structure in favor of (a slightly augmented version of) its connectome, and the entire chemical make-up of it in favor of its electrical connections. As I have mentioned, that is a mere model that represents a very lossy compression of what is going on; it is not the same as the real thing, and conflating the two is an error that has been going on here for far too long. Of course, it very well might be the case that Rob and the computationalists are right about these issues, but the explanation up to now should make it clear why it is on them to provide evidence for their conclusion.
The accuracy of this interpretation of the LW-computationalist view seems to have been confirmed by its proponents, implicitly by Bensinger continuing the conversation with andesoldes without mentioning any disagreement when the latter explicitly asked him "First off, would you agree with my model of your beliefs? Would you consider it an accurate description?" and by cousin_it saying that "uploading [going] according to plan" means "the map of your neurons and connections has been copied into a computer", and explicitly by Seth Herd claiming that "your mind is a pattern instantiated in matter" and by Bloom, who wrote the following:
To answer your question in your other comment. I reckon with some time I could write an explainer for why we should very reasonable assume consciousness is the result of local brain stuff and nothing else (and also not quantum stuff), though I'd be surprised if I could easily write something so rigorous that you'd find it fully satisfactory.
(Emphasis mine.)
When Seth Herd restated computationalist conclusions, once again without much argumentation ("Noncomputational physicalism sounds like it's just confused. Physics performs computations and can't be separated from doing that. Dual aspect theory is incoherent because you can't have our physics without doing computation that can create a being that claims and experiences consciousness like we do"), I summarized a relevant part of my skepticism as follows:
As I read these statements, they fail to contend with a rather basic map-territory distinction that lies at the core of "physics" and "computation."
The basic concept of computation at issue here is a feature of the map you could use to approximate reality (i.e., the territory) . It is merely part of a mathematical model that, as I've described in response to Ruby earlier, represents a very lossy compression of the underlying physical substrate [2]. This is because, in this restricted and epistemically hobbled ontology, what is given inordinate attention is the abstract classical computation performed by a particular subset of the brain's electronic circuit. This is what makes it anti-physicalist, as I have explained:
[...]
So when you talk about a "pattern instantiated by physics as a pure result of how physics works", you're not pointing to anything meaningful in the territory, rather only something that makes sense in the particular ontology you have chosen to use to view it through, a frame that I have explained my skepticism of already.
So, to finish up the exposition and background behind this question, what are the actual arguments in favor of the computationalist thesis? If you agree with the latter philosophy,[1] why do you not think it to be the case that computationalism is anti-physicalist by failing a basic map-territory distinction due to how it reifies ideas like "computation" as being parts of the territory as opposed to mere artifacts of a mathematical model that attempts, imperfectly and lossily, to approximate reality?
- ^
In my current model of this situation, I have some strong suspicions about the reasons why LW converged on this worldview despite the complete lack of solid argumentation in its favor, but I prefer to withhold the psychoanalysis and pathologizing of my interlocutors (at least until after the object-level matters are resolved satisfactorily).
Why? If I try to guess, I'd point at not often considering indexicality as a consideration, merely thinking of it as having a single utility function which simplifies coordination. (But still, a lot of decision theory doesn't need to take into account indexicality..)
I see the decision theory posts as less as giving new intuitions, and more breaking old ones that are ill-adapted, though that's partially framing/semantics.
I'll try to find some, but they're more likely to be side parts of comment chains rather than posts, which does make them more challenging to search for. I doubt they're as in-depth as we'd like, I think there is work done there, even if I do think the assumption of QM not mattering much is likely.
The basic idea is what would it give you? If the brain uses it for a random component, why can't that be replaced with something pseudorandom? Which is fine from an angle of not seeing determinism as a problem. If the brain utilizes entangled atoms/neurons/whatever for efficiency, why can't those be replaced with another method — possibly impractically inefficient? Does the brain functionally depend on an arbitrary precision Real for a calculation, why would it, and what would be the matter if it was cut off to N digits?
There's certainly more, but finding specific comments I've read over the years is a challenge.
I'm not sure I understand the distinction. Even if the true universe is a bunch of freeze-frame slices, time and change still functionally act the same. Given that I don't remember random nonsense in my past, there's some form of selection about which freeze-frames are constructed. Or, rather, with differing measure. Thus most of my 'future' measure is concentrated on freeze-frames that are consistent with what I've observed, as that has held true in the past.
Like, what you seem to be saying is Timeless Physics, of which I'd agree more with this statement:
So I'd agree that computation only makes sense with some notion of time. That there has to be some way it is being stepped forward. (To me this is an argument in favor of not privileging spatial position in the common teleportation example, but we've seemed to move down a level to whether the brain can be implemented at all)
I misworded what I say, sorry. I more meant that you consider it to say/imply nothing meaningful, but you can certainly still argue against it (such as arguing that it isn't coherent).
I would say the that the computer program running can be considered as an implementation of the abstract python code. I agree that this model is missing details. Such as the exact behavior of the transistor, how fast it switches, the exact positions of the atoms, etcetera. That is dependent on the mind considering it, I agree. The cosmic ray event would make so it is no longer an implementation of the abstract python program. You could expand the consideration to include more of the universe. Just as you could expand your model to consider the computer program as an implementation of the python program with some constraints: that if this specific transistor gets flipped one too many times it will fry, that there's a slight possibility of a race condition that we didn't consider at all in our abstract implementation, there's a limit to the speed and heat it can operate at, a cosmic ray could come from these areas of space and hit it with 0.0x% probability thus disrupting functionality...
It still seems quite reasonable to say it is an implementation of the python program. I'm open to the argument that there isn't a completely natural privileged point of consideration from which the computer is implementing the same pattern as another computer, and that the pattern is this python program. But as I said before, even if this is ultimately some amount of purely subjective, it still seems to capture quite a lot of the possible ideas?
Like in mathematics, I can have an abstract implementation of a sorting algorithm and prove that a python program for a more complicated algorithm (bubblesort, whatever) is equivalent. This is missing a lot of details, but that same sort of move is what I'm gesturing at.
I can understand why you think that just the neurons / connections is too lossy, but I'm very skeptical of the idea that we'd need all of the amplitudes related to the brain/mind. Apriori that seems unlikely whatwith how little fundamentally turns on the specifics of QM, and those that do can all be implemented specially. As I discussed above some.
(That also reminds me of another reason why people sometimes just mentions neurons/connections which I forgot in my first reply: because they assume you've gotten the basic brain architecture that is shared and just need to plug in the components that vary)
I disagree that this distinction between our model and reality has been lost, merely that it has been deemed not too significant, or as something you'd study in-depth when actually performing brain uploads.
As I said in my previous comment, and earlier in this one, I'm open to the idea of computation being subjective instead of a purely natural concept. Though I'd expect that there's not that many free variables in pinning down the meaning. As for tabooing, I think that is kind of hard, as one very simple way of viewing computation is "doing things according to rules".
You have an expression 5∗3. This is in your mind and relies on subjective interpretations of what the symbols mean. You implement that abstract program (that abstract doing-things, a chain of rules of inference, a way that things interact) into a computer. The transistors were utilized because they matched the conceptual idea of how switches should function, but they have more complexities than the abstract switch, which introduces design constraints throughout the entire chip. The chip's ALU implements this through a bunch of transistors, which are more fundamentally made up of silicon in specific ways that regulate how electricity moves. There's layers and layers of complexities even as it processes the specific binary representations of the two numbers and shifts them in the right way. But, despite all this, all that fundamental behavior, all the quantum effects like tunneling which restrict size and positioning, it is computing the answer. You see the result, 15, and are pretty confident that no differences between your simple model of the computer and reality occurred.
This is where I think arguments about subjectivity of computation can be made. Introduce a person who is talking about a different abstract concept, they encode it as binary because that's what you do, and they have an operation that looks like multiplication and produces the same answer for that binary encoding. Then, the interpretation of that final binary output is dependent on the mind, because the mind has a different idea of what they're computing. (But with the abstract idea being different, even if those parts match up) But I think a lot of those cases are non-natural, which is part of why I think even if computation doesn't make sense as a fundamental thing or a completely natural concept, it still covers a wide area of concern and is a useful tool. Similar to how the distinction of values and beliefs is a useful tool even when strictly discussing humans, but even moreso. So then, the two calculators are implementing the same abstract algorithm in their silicon, and then we fall back to two questions 1) is the mind within the edge-cases such that it is not entirely meaningful to talk about an abstract program that it is implementing 2) okay, but even if they share the same computation, what does that imply. I think there could and should be more discussion of the complications around computation, with the easy to confuse interaction between levels of 'completely abstract idea' (platonism?), 'abstract idea represented in the mind' (what I'm talking about with abstract; subjective), 'the physical way that all the parts of this structure behave' (excessive detail but as accurate as possible; objective), 'the way these rules do a specific abstract idea' (chosen because of abstract ideas like a transistor is chosen because it functions like a switch, and the computer program is compiled in such a way because it matches the textual code you wrote which matches the abstract idea in your own mind; objective in that it is behaving in such a way, possibly subjective interpretation of the implications of that behavior).
We could also view computation through the lens of Turing Machines, but then that raises the argument of "what about all these quantum shenanigans, those are not computable by a turing machine". I'd say that finite approximations get you almost all of what you want. Then there's the objection of "turing machines aren't available as a fundamental thing", which is true, and "turing machines assume a privileged encoding", which is part of what I was trying to discuss above.
(I got kinda rambly in this last section, hopefully I haven't left any facets of the conversation with a branch I forgot to jump back to in order to complete)