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Correspondence (matching theories to observations) is a subset of coherence (matching everything with everything)
It is a very useful subset as long as observations are reliable and easy to procure, which is in your case, and indeed in most, but not all cases it is so.
A counter-example would be Many-Worlds: you cannot match it with observations, but you can match it with other theories and see it follows the pattern.
Your observations rest on definitions which come from other parts of your knowledge. Trains depart on time? Down to the nanosecond level or second level will be okay? Is 10 secs late still okay? Based on the starter timezone, even if it goes through multiple ones? If they base departure time on starter time zone and arrival on destination time zone, won't it upset your expectation of the trip length? If not, can you miss a connection? What does ticket accepted mean, would presenting a false ticket and bribing the conductor would count as accepted? Would a well made false ticket that tricks all the conductors do? This is not nitpicking, it just means your observations are obvious because they rest on all kinds of non-conscious, tacit, consensual knowledge beyond that. And that is roughly what Quine meant: I can prove hardly any time train ever departs on time if I just make another change in the system, such as saying on time means nanosecond exactness. This is a change not worth making, of course.
Correspondence (matching theories to observations) is a subset of coherence (matching everything with everything)
Correspondence is not just matching theories to observation. It is matching theories to reality. Since we don't have pure transcendent access to reality, this involves a lot of matching theories to observation and to each other, and rejecting the occasional observation as erroneous; however, the ultimate goal is different from that of coherence, since perfectly coherent sets of statements can still be wrong.
If your point is that "reality" is not a meaningful concept and we should write off the philosophizing of correspondence theorists and just focus on what they actually do, then what they actually do is identical to what coherentists actually do, not a subset.
Is everybody going to have their own replicators on a spaceship? If so, just how big are they going to be? And, if they are big enough to replicate an elephant... then... it seems like it's useful to think of the alternative uses of the space that all the large replicators and their produced items take up on a ship with limited space.
So at no point do you ever truly get away from the benefit maximization problem. Right now I have a bunch of bookcases filled with books. In theory I could free-up a bunch of space by digitizing all my books. But then I'd still have to figure out what to do with the free space.
Basically, it's a continual process of freeing up resources for more valuable uses. Being free to valuate the alternatives is integral to this process. You can't free-up resources for more valuable uses when individuals aren't free to weigh and forego/sacrifice/give-up the less valuable alternatives.
Some good reading material...
Those are entirely valid points, but they only show that human desires are harder to satiate than you might think, not that satiating them would be insufficient to eliminate scarcity. And in fact, that could not possibly be the case even granting economy's definition of scarcity, because if you have no unmet desires, you do not need to make choices about what uses to put things to. If once you digitize your books, you want nothing in life except to read all the books you can now store, you don't need to put the shelf space to another use; you can just leave it empty.
You should add a link to the previous post at the top, so people who come across this don't get confused by the sand metaphor.
This will hopefully be addressed in later posts, but on its own, this reads like an attempt to legislate a definition of the word 'scarcity' without a sufficient justification for why we should use the word in that way. (It could also be an explanation of how 'scarcity' is used as a technical term in economics, but it is not obvious to me that the alternate uses/unsatiated desires distinction is relevant to what most economists spend their time on. If this is your intention, could you elaborate and give evidence that economists do in fact use the term in this way?) Naively, it seems that if we have enough Star Trek replicators or whatever to satiate all human desires, then for all practical purposes scarcity has been eliminated, and insisting that it hasn't really because things have alternative uses because some things still have alternative uses seems like playing unproductive word games. Can you explain why thinking of scarcity in your terms is advantageous?
Overall, this series has so far been quite fun to read. I look forward to more.
From Yudkowsky's Epistle to the New York Less Wrongians:
Knowing about scope insensitivity and diminishing marginal returns doesn't just mean that you donate charitable dollars to "existential risks that few other people are working on", instead of "The Society For Curing Rare Diseases In Cute Puppies". It means you know that eating half a chocolate brownie appears as essentially the same pleasurable memory in retrospect as eating a whole brownie, so long as the other half isn't in front of you and you don't have the unpleasant memory of exerting willpower not to eat it.
If you mainly value brownie-eating memories, this is perfectly reasonable advice. If you instead you eat brownies for the experience, it is unhelpful, since eating half a brownie means the experience is either half as long or less intense.
Is this the sort of thing you're looking for?
A utility function is a function, not a program. You could talk about whether or not it's computable. Since you can find a utility function by randomly putting the agent into various universes and seeing what happens, it's computable.
OrphanWilde appears to be talking about morality, not decision theory. The moral Utility Function of utilitarianism is not necessarily the decision-theoretic utility function of any agent, unless you happen to have a morally perfect agent lying around, so your procedure would not work.
It's fairly common in programming, particularly, to care not just about the average case behavior, but the worst case as well. Taken to an extreme, this looks a lot like Caul, but treated as a partial but not overwhelming factor, it seems reasonable and proper.
For example, imagine some algorithm which will be used very frequently, and for which the distribution of inputs is uncertain. The best average-case response time achievable is 125 ms, but this algorithm has high variance such that most of the time it will respond in 120 ms, but a very small proportion of the time it will take 20 full seconds. Another algorithm has average response time 150 ms, and will never take longer than 200 ms. Generally, the second algorithm is a better choice; average-case performance is important, but sacrificing some performance to reduce the variance is worthwhile.
Taking this example to extremes seems to produce Caul-like decisionmaking. I agree that Caul appears insane, but I don't see any way either that this example is wrong, or that the logic breaks down while taking it to extremes.
The most obvious explanation for this is that utility is not a linear function of response time: the algorithm taking 20 s is very, very bad, and losing 25 ms on average is worthwhile to ensure that this never happens. Consider that if the algorithm is just doing something immediately profitable with no interactions with anything else (e.g. producing some crytptocurrency), the first algorithm is clearly better (assuming you are just trying to maximize expected profit), since on the rare occasions when it takes 20 s, you just have to wait almost 200 times as long for your unit of profit. This suggests that the only reason the second algorithm is typically preferred is that most programs do have to interact with other things, and an extremely long response time will break everything. I don't think any more convoluted decision theoretic reasoning is necessary to justify this.
This is really nicely written, but unfortunately the main lesson for me is that I don't understand the Löb's Theorem. Despite reading the linked PDF file a few times. So I guess I will use this place to ask you a few things, since I like your way of explaining.
First, I may have just ruined my math credentials by admitting that I don't understand Löb's Theorem, but it doesn't mean that I suck at maths completely. I feel pretty confident in elementary- and maybe even high-school math. Let's say that I am confident I would never tell someone that 2+2=3.
Second, if I understand the rules for implication correctly, if the premise is false, the implication is always true. Things like "if 2+2=3, then Eliezer will build a Friendly AI" should be pretty non-controversial even outside of LessWrong.
So it seems to me that I can safely say "if I tell you that 2+2=3, then 2+2=3". (Because I know I would never say that 2+2=3.)
But Mr. Löb insists that it means that I just claimed that 2+2=3.
And I feel like Mr. Löb is totally strawmanning me.
Please help!
Part of the issue is that you are not subject to the principle of explosion. You can assert contradictory things without also asserting that 2+2=3, so you can be confident that you will never tell anyone that 2+2=3 without being confident that you will never contradict yourself. Formal systems using classical logic can't do this: if they prove any contradiction at all, they also prove that 2+2=3, so proving that they don't prove 2+2=3 is exactly the same thing as proving that they are perfectly consistent, which they can't consistently do.
You cannot possibly gain new knowledge about physics by doing moral philosophy. At best, you have shown that any version of utilitarianism which adheres to your assumptions must specify a privileged reference frame in order to be coherent, but this does not imply that this reference frame is the true one in any physical sense.
Let me see if I can put that in my own words; if not, I didn't understand it. You are saying that humans, who do not operate strictly by PA, know that a proof of the existence of a proof is itself a proof; but a reasoner strictly limited to PA would not know any such thing, because it's not a theorem of PA. (PA being just an example - it could be any formal system, or at least any formal system that doesn't include the concept of proofs among its atoms, or concepts.) So such a reasoner can be shown a proof that a proof of A exists, but will not know that A is therefore a theorem of PA. Correct?
To me this seems more like a point about limitations of PA than about AI or logic per se; my conclusion would be "therefore, any serious AI needs a formal system with more oomph than PA". Is this a case of looking at PA "because that's where the light is", ie it's easy to reason about; or is there a case that solving such problems can inform reasoning about more realistic systems?
Strictly speaking, Lob's Theorem doesn't show that PA doesn't prove that the provability of any statement implies that statement. It just shows that if you have a statement in PA of the form (If S is provable, then S), you can use this to prove S. The part about PA not proving any implications of that form for a false S only follows if we assume that PA is sound.
Therefore, replacing PA with a stronger system or adding primitive concepts of provability in place of PA's complicated arithmetical construction won't help. As long as it can do everything PA can do (for example, prove that it can prove things it can prove), it will always be able to get from (If S is provable, then S) to S, even if S is 3*5=56..
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Very interesting post, but your conclusion seems too strong. Presumably, if instead of messing around with artificial experiencers, we just fill the universe with humans being wireheaded, we should be able to get large quantities of real pleasure with fairly little actually worthwhile experiences; we might even be able to get away with just disembodied human brains. Given this, it seems highly implausible that if we try to transfer this process to a computer, we are forced to create agent so rich and sophisticated that their lives are actually worth living.