David Deutsch on How To Think About The Future

[-]Vladimir_Nesov14y480

Deutsch argues that the future is fundamentally unpredictable, that for example expected utility considerations can't be applied to the future, because we are ignorant of the possible outcomes and intermediate steps leading to those outcomes, and the options that will be available; and there is no way to get around this. The very use of the concept of probability in this context, Deutsch says, is invalid.

As illustration, among other things, he lists some failed predictions made by smart people in the past, attributing failure to unavailability of the ideas relevant for the predictions, ideas that will only be discovered much later.

[Science can't] predict any phenomenon whose course is going to be affected by the growth of knowledge, by the creation of new ideas. This is the fundamental limitation on the reach of scientific explanation and prediction.
[Predictions that are serious attempts to extract unknowable answers from existing knowledge] are going to be biased towards bad outcomes.

(If it's unknowable, how can we know that a certain prediction strategy is going to be systematically biased in a known direction? Biased with respect to what knowable standard?)

Deutsch explains... (read more)

5timtyler14y

This bit starts about 12 minutes in. It is complete nonsense - Deutsch does not have a clue about the subject matter he is talking about :-(

4XiXiDu14y

This is a really good point. When I read it I first thought I would have to disagree, after all we've designed the chess AI and therefore do understand it. But since I am currently reading Daniel Dennett's 'Darwin's Dangerous Idea' my next thought was that disagreeing with it seems to be a general bias assuming that a design is always inferior to its designer. But it should be obvious that our machines are faster and stronger than us, why not better thinkers too? Unlike the blind idiot God we can pinpoint our own flaws and devise solutions but are also unable to apply them to ourselves effectively, which will be realized by the next level of self-redesigning things. But even now our designs can be superior to us as they mirror our own improved upon capabilities, our skills minus our flaws. We are still able to understand our machines but unable to mimic their capabilities as we've been able to recreate some of our skills but haven't been able to benefit from the improvements we devised. We know that steel is tougher than bones, beware "steel" that knows this fact as well.

2XiXiDu14y

I just realized you tried to make a different point here. That one can prove the behavior of computationally unpredictable systems. Reminds me of the following: Sounds reasonable but I have no idea to what extent one could prove "friendliness" while retaining a degree of freedom that would allow a seed AI to recursively-selfimprove towards superhuman intelligence quickly. Intuitively it seems to me that the level of abstraction of a definition of "friendliness" will be somehow correlated with the capability of an AGI.

0curi14y

No. Deutsch's "principle of optimism" states: optimism demands that they can live happily ever after if they learn how. it does not predict that they will.

0Vladimir_Nesov14y

Agreed. The "we all live happily ever after" inference does contradict Deutsch's idea, which I noticed a little after writing this, and so corrected the wording (before seeing your comment) thusly:

-1timtyler14y

This is surely a real effect. The government is usually stronger than the mafia. The army is stronger than the terrorists. The cops usually beat the robbers, etc.

-1curi14y

He doesn't consider it obvious. He considers nothing obvious in general (in a serious, not vacuous way). This in particular he has thought about, not because it is obvious but because it isn't. The basic reason "good guys" make progress faster than "bad guys" (in the sense of: immoral guys, like prone to violence) is that they have more stable, peaceful, cooperative societies that are better suited to making progress. It's because good values are more effective in real life. There's discussion of this stuff in his book The Beginning of Infinity.

7JoshuaZ14y

This sort of claim seems to run into historical problems. A lot of major expansionist violent empires have done quite well for themselves. In modern times, some of the most "bad" groups have done well as well. The Nazis in many ways had much better technology than the Allies. If they hadn't been ruled by an insane dictator they would have done much better. Similarly, if they had expanded just as much but waited to start the serious discrimination and genocide until after they already had won they would have likely won. Similarly, in WW2, Japan did quite well for itself, and if a handful of major battles had gone slightly differently, the outcome would have been very different. Or to use a different, but potentially more controversial example, in North America and in Australia, the European colonizers won outright, despite having extremely violent, expansionist policies. In North America, you actually had multiple different European groups fighting amongst themselves as well and yet they still won. Overall, this is a pleasant, optimistic claim that seems to be depressingly difficult to reconcile with actual history.

[-]Randaly14y140

It's worth noting that most of the Nazi superiority in technology wasn't actually due to Nazi efforts, but rather due to a previous focus on technological and scientific development; for example, Germans won 14 of the first 31 Nobel Prizes in Chemistry, the vast majority of initial research into quantum mechanics was done by Germans, etc. But Nazi policies actually did actively slow down progress, by e.g. causing the emigration of free-thinking scientists like John von Neumann, Hans Bethe, Leo Szilard, Max Born, Erwin Schrodinger, and Albert Einstein, and by replacing empirically based science with inaccurate political ideology. (Hitler personally believed that the stars were balls of ice, tried to avoid harmful "earth-rays" mapped out for him with a dowsing rod, and drank a toxic gun-cleaning fluid for its supposed health benefits, not to mention his bizarre racial theories.) Membership in the Society of German Natural Researchers and Physicians shrank nearly in two between 1929 and 1937; during World War II, nearly half of German artillery came from its conquered neighbors, its supply system relied in part on 700,000-2,800,000 horses, its tanks and aircraft were in many... (read more)

9Vladimir_M14y

According to this article published by the German Federal Archives, 2.8 million horses served in the German armed forces in WW2. The article also notes how successfully the German wartime propaganda portrayed the Wehrmacht as a high-tech motorized army, an image widely held in the public to this day, while in reality horses were its main means of transport.

4JoshuaZ14y

You make a very strong case that the Nazi example does go in the other direction. I withdraw that example. If anything it goes strongly in favor of Deutsch's point. I'm not convinced by the relevancy of your point about the historical state during the colonization of North America. The point is not whether or not someone eventually transformed, the point is that violent, expansionist groups can win over less expansionist groups.

0curi14y

Deutsch's definition of "the bad guys" is not the most expansionist groups. He would regard the colonizers as the good guys (well, better guys) because their society was less static, more open to improvement, more tolerant of non-conformist people, more tolerant of new ideas, more free, and so on. There's a reason the natives had worse technology and their culture remained static for so long: they had a society that squashes innovation.

5JoshuaZ14y

You'd have to convince me that they were more open to non-conformists. A major cause of the European colonization was flight of non-conforming groups (such as the Puritans) to North America where they then proceeded to persecute everyone who disagreed with them. I'm curious what you think of "Guns, Germs, and Steel" or similar works. What causes one society or another to adopt or even make innovations can be quite complicated.

7Randaly14y

The Renaissance/much of modern science originated in Italy, not in England (thus, e.g. Galileo, da Vinci, etc.) And the Italian city-states of the time were fairly free: Pisa, Milan, Arezzo, Lucca, Bologna, Siena, Florence, and Venice were all at some point governed by elected officials. They were also remarkably meritocratic: as the influential Neapolitan defender of atomism Francesco D'Andrea put it, describing Naples: (Even if he's only boasting about his own city-state, it's significant that meritocracy was considered worth boasting about.) Similarly, merchants, not priests, politicians, etc. were considered the highest status group: nobles up to and including national leaders (e.g. the Doge of Venice) dressed like merchants. (Incidentally, the other factors you mentioned below also played a role: competition between city-states and the influence of outside science from Byzantium and the Islamic world showing what could be done. Nevertheless, Italian freedoms were also necessary: e.g. Galileo was only able to publish his ideas because he lived in the free Republic of Venice, where Jesuits were banned and open inquiry encouraged; he was persecuted and forced to recant his theories when he moved to Tuscany.)

-4curi14y

read The Beginning of Infinity by Deutsch. It discusses that Diamond book and other similar works. Yes European society was not favorable to non-conformists. One period I've studied, which is later (so, i think, better in this regard) is around 1790 ish. At that time, to take one example, the philosopher william godwin's wife died in childbirth and he published memoirs and people got really pissed off because she had had sex out of wedlock and stuff along those lines. when godwin's daughter ran off with shelley there were rumors he had sold her. meanwhile, for example, there was lots of discrimination against irish catholics. i know some stuff about how biased and intolerant people can be. but what i also know is a bit about static societies (again, see the book for more details, or at least check out my website, e.g. http://fallibleideas.com/tradition). when a society doesn't change for thousands of years that means it's even harsher than the european society i was talking about. preventing change for such a long period is hard. stuff is done to prevent it. the non-conformists don't even get off the ground. everyone's spirits are squashed in childhood -- thoroughly -- and so the adults don't rebel at all. if there were adults who were eccentric then the society simply wouldn't stay the same so long. european society was already getting fairly near fairly rapid changes (e.g. industrial revolution) when it started colonizing the new world.

5JoshuaZ14y

This doesn't follow. (Incidentally, I don't know why you sometimes drop back to failing to capitalize but it makes what you write much harder to read.) For example, if one doesn't have good nutrition then people won't be as smart and so won't innovate. Similarly, if one doesn't have free time people won't innovate. Some technologies and cultural norms also reinforce innovation. For example, having a written language allows a much larger body of ideas, and having market economies gives market incentives to coming up with new technologies. Moreover, innovation can occur directly through competition. When you are convinced that your religion or tribe is the best and that you need to beat the others by any means necessary you'll do a lot better at innovating. There's also a self-reinforcing spiral: the more you innovate the more people think that innovation is possible. If your society hasn't changed much then there's no reason to think that new technologies are easy to find. There's no reason to think that Native American populations were systematically preventing change. There's a very large difference between having infrastructural and systemic issues that make the development of new technologies unlikely and the claim that "everyone's spirits are squashed in childhood -- thoroughly".

-15curi14y

1JoshuaZ14y

Minor remark: Your essay about tradition is much more readable than a lot of the other material on your site. I'm not sure why but if you took a different approach to writing/thinking about it, you might want to apply that approach elsewhere.

0curi14y

I think the difference is you. I wrote that entire site in a short time period. I regard it as all being broadly similar in style and quality. I attempted to use the same general approach to the whole site; I didn't change my mind about something midway. I think it's a subject you understand better than epistemology directly (it is about epistemology, indirectly. traditions are long lived knowledge). The response I've had from other readers has varied a lot, not matched your response. I do know how to write in a variety of different styles, and have tried each in various places. The one I've used here in the last week is not the best in various senses. But it serves my purpose.

3Desrtopa14y

The first example that comes to mind for me is the collapse of the Roman empire. The Romans might have been "bad", being aggressive and expansionist, but the people they fell to were markedly worse from the perspective of truth seeking and pursuit of enlightenment, the standard Deutsch and curi are applying, and their replacements ushered in the Dark Ages.

[-]Randaly14y100

But different conditions hold today. The Gothic armies were virtually identical to the armies of the earlier Celts/Gauls who the Romans had crushed; even the Magyars (~1500's CE) used more or less the same tactics and organization as the Cimmerians (~ 700 BCE), though they did have stirrups, solid saddle trees, and stiff-tipped composite bows. Similarly, IIRC, the Roman armies didn't make use of any major recent technological innovations. This no longer holds today; the idea of an army using technology hundreds of years old being a serious military threat to any modern nation is frankly ludicrous. Technological and scientific development has become much, much more important than it was during Roman times.

(And, btw, it's not really accurate to say that, in practice, the barbarians were all that much much worse than the Romans in terms of development and innovation; technological development in Europe didn't really slow down all that much during the Dark Ages and the Romans had very few scientific (as opposed to engineering) advances anyways- most of their scientific knowledge (not to mention their mythology, art, architecture, etc.) was borrowed from the Greeks.)

-2Desrtopa14y

Yes, but the culture of enlightenment and innovation within Greek and Roman culture had already been falling apart from within. The culture of Classical Antiquity was outcompeted by less enlightened memes.

2Randaly14y

How so? I'm not sure when, specifically, you're talking about, but the post-expansion Roman Empire still produced such noted philosophers as Marcus Aurelius, Apuleius, Boethius, St. Augustine, etc.

1Desrtopa14y

I'm thinking of the decline of Hellenist philosophy, especially the mathematical and empirical outlooks propounded by those such as Hypatia.

4Jayson_Virissimo14y

As far as I know, Hypatia was a Neoplatonist like Saint Augustine. What evidence do you know of that she had an empirical outlook?

0Desrtopa14y

That was a position she had attributed to her in a book in which I first read about her; I no longer remember the details and may have been mistaken. In any case, the development of new technology and naturalistic knowledge based on empirical investigation and mathematics declined in the Dark ages. Whether I was mistaken about Hypatia's position in particular or not doesn't change the issue of whether an inferior tradition of intellectual investigation replaced a superior one.

7Vladimir_M14y

Was it by any chance Cosmos by Carl Sagan? His treatment of the topic is complete nonsense. (I understand Sagan is held in some respect by many people here, but he definitely wasn't above twisting facts and perpetuating myths to advance his agenda.) A good debunking of the whole "Hypatia as a rationalist martyr" myth can be found on Armarium Magnum.

0Desrtopa14y

I'm pretty sure I've never read Cosmos, so no, I don't think so. If it's a myth, he's not the only one perpetuating it.

3[anonymous]14y

Read Cosmos? Once again I feel antiquated.

1Jayson_Virissimo14y

In that case, I won't update my beliefs. Was that from a blurb in a science textbook by chance? I too have been the victim of false history from my science textbooks. What time period are you referring to when you use the term Dark Ages? If you are referring to the Middle Ages, then I disagree that it is an example of a time when a superior intellectual tradition was replaced by an inferior one (at least in terms of natural philosophy/science).

0Desrtopa14y

It was a history book (popular, not academic,) and it's certainly possible that it was mistaken. The limits of the Dark Ages are a matter of historical dispute, but for the purposes of this discussion, I suppose we could say about 5th to 11th century CE in Europe.

2Jayson_Virissimo14y

I agree that the Dark Ages had an inferior intellectual tradition than the Hellenistic Period, since the dates you stipulated would exclude Aquinas, Ockham, and Scotus. On the other hand, I am at a loss trying to think of 11th century technologies that weren't equal to or superior than their 4th century counterparts.

1Randaly14y

Well of course the previously dominant branch of philosophy declined- that happens all the time in philosophy. But I don't think that there's grounds for proclaiming Hellenist philosophy to be significantly better than its successors: it was hardly empirical (Hypatia herself was an anti-empirical Platonist) and typically more concerned with e.g. confused explanations of the world in terms of a single property (all is fire! no, water!) or confusion regarding words (e.g. the Sorites paradox) than any kind of research valuable/relevant today. And the group which continued the legacy of Hellenist/Roman thought, the Islamic world, did in fact continue and, IMHO, vastly augment the level of empirical thought; for example, it's widely believed that the inventor of the Scientific Method was an Arab scientist, Alhazen. Even though Europe saw a drop in learning due to the collapse of the unsustainable centralized Roman economy and the resulting wars and deurbanization, all that occurred was that its knowledge was passed onto new civilizations large/wealthy/secure enough to support science/math/philosophy. (Specifically, Persia and Byzantium, and later the Caliphates.)

2Desrtopa14y

The technological and empirical tradition of Islam pretty much died out due to the success of The Incoherence of the Philosophers though. My point is that innovative and empirical traditions have given way in the past to memetically stronger anti-innovative traditions. That doesn't mean that the same will happen to present day scientific culture, I highly doubt that would happen without some sort of catastrophic Black Swan event, but innovative traditions have not historically consistently beaten out non innovative ones.

1Randaly14y

But there were still significant Islamic achievements in science after The Incoherence of the Philosophers was published- e.g. Ibn Zuhr's experimental scientific surgery, Ibn al-Nafis's discovery of pulmonary circulation, etc. And The Incoherence of the Philosophers probably didn't have much of an impact, at least immediately, on Islamic science- Al-Ghazali only critiqued Avicenna's philosophy, while expressing support for science. I think a more persuasive reason for the decline of Islamic science is the repeated invasions by outsiders (Crusaders, Mongols, Beduins, and the Reconquista, plus the Black Plague), which pretty much ended the golden age of Islamic civilization. But today, as I said earlier, there are no powerful yet unknown barbarian hordes around today. (Though yes, I agree wrt Black Swans like the Black Plague.)

1Eugine_Nier14y

I think this is caused by the fact that innovative societies are that way because their more open to new ideas. But being open to new ideas means that your memetic defenses are by definition weaker. Notice also that innovative societies generally aren't defeated until they stop innovating.

0[anonymous]14y

The "Hypatia as a rationalist hero" trope is one of those awful historical myths that just refuse to die out. Armarium Magnum has a detailed debunking of the story.

[-]Vladimir_M14y130

Similarly, in WW2, Japan did quite well for itself, and if a handful of major battles had gone slightly differently, the outcome would have been very different.

You are wrong about this. Even if every single American ship magically got sunk at some point in 1941 or 1942, and if every single American soldier stationed outside of the U.S. mainland magically dropped dead at the same time, it would only have taken a few years longer for the U.S. to defeat Japan. Once the American war production was up and running, the U.S. could outproduce Japan by at least two orders of magnitude and soon overwhelm the Japanese navy and air force no matter what their initial advantage. Starting the war was a suicidal move for the Japanese leadership, and even the sane people among them knew it.

I think you're also overestimating the chances Germans had, and underestimating how well Hitler did given the circumstances, though that's more controversial. Also, Germany lost the technological race in pretty much all theaters of war where technology was decisive -- submarine warfare, cryptography, radars and air defense, and nuclear weapons all come to mind. The only exceptions I can think of are jet aircr... (read more)

7JoshuaZ14y

Ok. So all my World War 2 examples have now decisively been shown to be wrong. I don't have any other modern examples to give that go in this direction. All other modern examples go pretty strongly in the other direction. I withdraw the claim wholesale and am updating to accept the claim for post-enlightenment human societies.

-6curi14y

-1curi14y

The idea is: if you're going to pull the trigger once every 100 years, instead of once every 5, and it's a 2% chance of doom each time, you're still doomed eventually. Any static society is doomed in that way. The delays don't help anything because nothing is changing in the mean time, so eventually doom happens. The attitude of not making progress, but just trying to sustain a fixed lifestyle forever, cannot work. Even if the chance of doom per year is made low, there is some chance so it will have to destroy them eventually. There's nothing to stop it from doing so. It's only in a dynamic society creating new knowledge and progress that lasting longer matters to whether you're doomed eventually, b/c in that extra time more progress is made.

-1curi14y

I forget how much detail there is on this later in this talk, but it is in his book. The systematic bias towards pessimism is due to the method of trying to imagine the future using today's knowledge (which is less than the future's knowledge). Quoting Deutsch from The Beginning of Infinity:

[-]FAWS14y110

It's inconsistent to expect the future to be better than one expects. If you think your probability estimates are too pessimistic adjust them until you don't know whether they are too optimistic or too pessimistic. No one stops you from assigning probability mass to outcomes like "technological solution that does away with problem X" or "scientific insight that makes the question moot". Claimed knowledge that the best possible probability estimate is biased in a particular direction cannot possibly ever be correct.

-17curi14y

[-]Manfred14y170

I stopped listening fairly quickly, after determining that it was rubbish from a Bayesian perspective. Specifically I stopped listening when he says that the future of humanity is different from russian roulette because the future can't be modeled by probability. This is the belief that there is a basic "probability-ness" that dice have and gun chambers have but people don't, and that things with "probability-ness" can be described by probability, but things without "probability-ness" can't be. But of course, we're all fermions and bosons in the end - there is no such thing as "probability-ness," probability is simply what happens when you reason from incomplete information.

5NancyLebovitz14y

Duetsch is arguing (and I think correctly) that there's a difference between knowing the full range of possibilities in a system and not knowing it.

7Manfred14y

That seems pretty reasonable. "What will the future be like" is a pretty undetermined question. However, he was applying this same logic to "will civilization be destroyed," where "destroyed" and "not destroyed" are a pretty complete range of possibilities. Unless maybe he meant that you have to know every possible way civilization could be destroyed in order to estimate a probability, which seems like searching for a reason that civilization doesn't have probability-ness.

[-]Vladimir_Nesov14y170

I think this talk motivates a Yudkowsky-Deutsch debate on bloggingheads.

1Alex Flint14y

Oh boy oh boy oh boy that would rock my socks

[-]CarlShulman14y120

This should not have been made as a top-level post without some more explanation to let people evaluate whether to watch the video.

-5curi14y

[-]Vladimir_Nesov14y80

It is a talk given to the Oxford Transhumanists. Their previous speaker was Eliezer Yudkowsky.

To clarify what I originally misinterpreted on reading this description: according to this page, Yudkowsky was giving a talk on 25 Jan 2011, while Deutsch on 10 Mar 2011, so "previous speaker" doesn't refer to giving talks in succession.

[-]Perplexed14y50

Thanks for posting this. I would definitely enjoy seeing a debate between Deutsch and Yudkowsky.

The part that dealt with ethics was incredibly naive. About 47 minutes in, for example, he is counseling us not to fear ET, because ET's morality will inevitably be superior to our own. And the slogan: "All evils are due to lack of knowledge". Why does this kind of thing remind me of George W. Bush?

But I agreed with some parts of his argument for the superiority of a a Popperian approach over a Bayesian one when 'unknown unknowns' regarding the gro... (read more)

7Eugine_Nier14y

Well, it reminds me of Plato, which is much more damning.

0timtyler14y

This seems pretty daft to me too. It looks like a kind of moral realism - according to which being eaten by aliens might well be "good" - since it leads to more "goodness".

2Perplexed14y

Right. But moral realism is not necessarily daft. It only becomes so when you add in universalism and a stricture against self-indexicality.

2timtyler14y

I have some sympathies for the idea that convergent evolution is likely to eventually result in a universal morality - rather than, say, pebble sorters and baby eaters. If true, that might be considered to be a kind of moral realism.

3Perplexed14y

It is a kind of moral realism if you add in the proclamation that one ought to do now that which we all converge toward doing later. Plus you probably need some kind of argument that the limit of the convergence is pretty much independent of the starting point. My own viewpoint on morality is closely related to this. I think that what one morally ought to do now is the same as what one prudentially and pragmatically ought to do in an ideal world in which all agents are rational, communication between agents is cheap, there are few, if any, secrets, and lifetimes are long. In such a society, a strongly enforced "social contract" will come into existence, which will have many of the characteristics of a universal morality. At least within a species. And to some degree, between species.

1timtyler14y

...or if you think what we ought to be doing is helping to create the thing with the universal moral values. I'm not really convinced that the convergence will be complete, though. If two advanced alien races meet, they probably won't agree on all their values - perhaps due to moral spontaneous symmetry breaking - and small differences can become important.

-1curi14y

You should read his book, The Beginning of Infinity. It's not a slogan but a philosophical position which he explains at length. Learn why he thinks it. He's not an idiot. Since you partly agree with him, and have mixed feelings, I think it'd be worth looking into for you, so I wanted to let you know it's much more than a slogan! And "optimism" to DD does not mean "predicting a positive future", it's not about wearing rose colored glasses.

[-]Vladimir_Nesov14y40

From the very beginning of the talk:

I don't have to persuade you that, for instance, life is better than death; and I don't have to explain exactly why knowledge is a good thing, and that the alleviation of suffering is good, and communication, and travel, and space exploration, and ever-faster computers, and excellence in art and design, all good.

One of these things is not like the others.

6lukeprog14y

Ever-faster computers jumped out at me when I first heard that sentence.

0Matt_Simpson14y

me too. Instrumental vs terminal values.

0JoshuaZ14y

Really? The comment about art and design jumped out at me.

2curi14y

FYI DD's talk on why flowers are beautiful: http://193.189.74.53/~qubitor/people/david/index.php?path=Video/Why%20Are%20Flowers%20Beautiful That URL is weird. In case it breaks, it's on youtube in parts: http://www.youtube.com/watch?v=56o2n8sVvM8

5curi14y

Which?

[-]Larks14y20

It's slow loading for me due to a slow internet connection, but if the questions at the end are included, I was the one who asked about insurance companies.

I don't think his response was very satisfactory, though I have a better version of my question.

Suppose I give you some odds p:q and force you to bet on some proposition X (say, Democrats win in 2012) being true, but I let you pick which side of the bet you take; a payoff of p if X is true, or a payoff of q if X is false. For some (unique) value of p/q, you'll switch which side you want to take.

It seems this can force you to assign probabilities to arbitrary hypothesis.

1Eugine_Nier14y

So, how precise should these probabilities be? Any why can't I apply this argument to force the probabilities to have arbitrary high precision?

2Larks14y

Not that I can think of, besides memory/speed constaints, and how much updating you can have done with the evidence you've recieved.

1Eugine_Nier14y

Why can't it happen that you have so little and/or such weak evidence, that the amount of precision you should have is none at all?

2Manfred14y

Imagine that you had to give a probability density to each probability estimate you could make of Obama winning in 2012 being the correct one. You'd end up with something looking like a bell curve over probabilities, centered somewhere around "Obama has a 70% (or something) chance of winning." Then to make a decision based on that distribution using normal decision theory, you would average over the possible results of an action, weighted by the probability. But this is equivalent to taking the mean of your bell curve - no matter how wide or narrow the bell curve, all that matters to your (standard decision theory) decision is the location of the mean. Less evidence is like a wider bell curve, more evidence like a sharper one. But as long as the mean stays the same, the average result of each decision stays the same, so your decision will also be the same. So there are two kinds of precision here: the precision of the mean probability given your current (incomplete) information, which can be arbitrarily high, and the precision with which you estimate the true answer, which is the width of the bell curve. So when you say "precision," there is a possible confusion. Your first post was about the "how precise can these probabilities be," which was the first (and boring, since it's so high) kind of precision, while this post seems to be talking about the second kind, the kind that is more useful because it reflects how much evidence you have.

1Eugine_Nier14y

I'm not sure what you mean by the "true answer". After all, in some sense the true probability is either 0 or 1 it's just that we don't know which.

1Manfred14y

That's a good point. So I guess the second kind of precision doesn't make sense in this case (like it would if the bell curve were over, say, the number of beans in a jar), and "precision" should only refer to "precision with which we can extract an average probability from our information," which is very high.

0[anonymous]14y

Bell curves prefer to live on unbounded intervals! It would be less jarring, (and less convenient for you?), if he ended up with something looking like a uniform distribution over probabilities.

0Manfred14y

It's equally convenient, since the mean doesn't care about the shape. I don't think it's particularly jarring - just imagine it going to 0 at the edges. The reason you'll probably end up with something like a bell curve is a practical one - the central limit theorem. For complicated problems, you very often get what looks something like a bell curve. Hardly watertight, but I'd bet decent amounts of money that it is true in this case, so why not use it to add a little color to the description?

0Larks14y

Well, your prior gives you a unique value, and bayes theorem is a function, so it gives you a unique value for every input.

1Eugine_Nier14y

So the claim is that you have arbitrary precision priors. What are they, and where are they stored?

0Larks14y

Sorry, I haven't been very clear. A perfect bayesian agent would have a unique real number to represent it's level of belief in every hypothesis. The betting-offer system I described about can force people (and force any hypothetical agent) to assign unique values. Of course, an actual person won't be capable of this level of precision or coherence.

0Eugine_Nier14y

Yes, but actually computing that function is computationally intractable in all but the simplest examples.

-10curi14y

[-]NancyLebovitz14y10

My first reaction to his unlimited progress riff was "every specific thing I care about will be gone". The answer is presumably that there will be more things to care about. However, that initial reaction is probably common enough that it might be worth working on replies to people who are less inclined to abstraction than I am.

I'll take the edge off his optimism somewhat by pointing out that individuals and cultures can be rolled over by change, even if the whole system is becoming more capable, and we care about individuals and cultures (especi... (read more)

[-]JGWeissman14y10

How was Curi able to post this without having 20 karma?

3curi14y

I had 20 karma. I don't anymore. My karma has had a lot of fluctuations. edit: see. back to 21 now.

[-]timtyler14y00

Deutsch gives Malthus as an example of a failed pessimistic prediction - at 23:00. However, it still looks as though Malthus is likely to have been correct. Populations increase exponentially, while resources expand at most in a polynomial fashion - due to the light cone. Deutsch discusses this point 38:00 minutes in, claiming relatavistic time dilation changes this conclusion, which I don' t think it really does: you still wind-up with most organisms being resource-limited, just as Malthus described.

[-]timtyler14y00

Martin Rees is misrepresented 4:04 in. What Rees actually said was:

the odds are no better than 50-50 that our present civilisation on Earth will survive to the end of the present century without a serious setback'

...whatever a "serious setback" is supposed to mean.

2vallinder14y

Do you have a reference for that? My copy of Our Final Hour contains the same sentence minus "without a serious setback".

2timtyler14y

Our Final Century, page 8 line 4. It seems as though Rees - rather confusingly - said different things on the topic in Our Final Century and Our Final Hour.

2vallinder14y

Ah, that's interesting. Thanks for clarifying.

LESSWRONG
LW

LESSWRONG
LW

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David Deutsch on How To Think About The Future

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