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Antievolution.org Discussion Board > From the Panda's Thumb > After the Bar Closes... > Missing Shade of Blue Thread

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keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 23 2008,13:53    Quote (Missing Shade of Blue @ Dec. 23 2008,11:11) The assumption here is that grue-bleen has to have this multi-component structure but blue-green does not. Why? Because grue-bleen involves a switch to different properties but blue-green does not. But that is only true in the blue-green basis. If you represent the situation using grue and bleen as natural predicates, then it is the blue-green system that is preparing for a switch. MSB, First you asked us how it was possible for natural selection to settle on a blue/green inductive bias when, according to you, a grue/bleen bias would have been equally valid. Now you're telling us that the choice of inductive bias makes no difference.  In a grue/bleen world, a grue/bleen detector has exactly the same structure as a blue/green detector in a blue/green world.  Natural selection gets it right either way by producing the simpler design. That renders your initial question nonsensical, because it means that natural selection didn't have to single out one bias or the other. It chose both. ETA:  Looks like R. Bill beat me by a few minutes. -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

dvunkannon Posts: 1377 Joined: June 2008 (Permalink) Posted: Dec. 23 2008,14:01    Quote (Missing Shade of Blue @ Dec. 23 2008,00:13) So the enhanced physical complexity of a grue detector is a red herring. A grue detector would only need to be more physically complex if grue were not a projectible predicate. But that is just to assume what needs to be proved. OK, I'll admit to following the discussion to this point without knowing what you mean by projectible. From nosing around on the internet, I can't find a definition of "projectible" that sounds different than "useful for induction". Is that how you mean it? Just to help me out on the whole grue/bleen thing, let's say it's a short time before time 't' and I have an emerald with a light shining on it. The reflected light passes through a beam splitter and one half goes through a long piece of fiber optic cable. Time 't' passes. If the photons exiting the cable are compared to the photons coming directly from the emerald, is there a short time when a machine or a human could detect that one stream was grue and the other was bleen? Are we discussing labels that humans put on their mental states, the perception of color by a species of primates, or dramatic changes in the real world? A good part of this discussion feels like "after 2012, we have always been at war with Eastasia." -------------- I’m referring to evolution, not changes in allele frequencies. - Cornelius Hunter I’m not an evolutionist, I’m a change in allele frequentist! - Nakashima

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,14:03    Quote I've only a moment, but think about what you have predicted: You've predicted that just one of these variants will be evident.   Not because of evolutionary prescience, but because of the action of selection. I'm really not sure what you're saying here. But let me try to clarify my view. In crude terms, there are two aspects to the blue-green (or grue-bleen) inductive system. There's the detection system and there's the response system. Now the supposition is that the detection system is identical for blue-green and grue-bleen creatures. It's not that one of them has a more elaborate system made up of multiple filters and timers or whatever. No, they both have the same detection system. Now if we are being truly neutral with respect to these inductive biases, we must concede that we do not know if this detection system detects grue or green (i.e. we do not know whether the detector gives stable output when presented with grue or green input). Given its performance so far, it could be either one. We'll only find out for sure in 2012. Now where the creatures differ is in their response systems. The blue-green creatures respond to particular detections with green-type expectations about the future. The grue-bleen creatures respond to the same detections with grue type expectations about the future. Given that their detection systems are identical, one of these creatures is going to be surprised come 2012 because its expectation system does not match its detection system. Its expectations will diverge from its detections. Again, without assuming an inductive bias ourselves, we cannot predict which creature will be surprised. Now my claims were that: (a) These creatures are, ceteris paribus, equally fit prior to 2012. (b) There's no obvious sense in which one creature has all the components of the other plus some more. They have the same detection system and different response systems. Both of these systems will be subject to selection (against other such systems) prior to 2012, but they remain neutral relative to each other until 2012. There is no exploitable asymmetry here until 2012. So given this description, in what sense have I predicted that "just one of these variants will be evident"?

midwifetoad Posts: 4003 Joined: Mar. 2008 (Permalink) Posted: Dec. 23 2008,14:16    I haven't seen any discussion of learning in this discussion. Since any discussion of detection and interpretation necessarily assumes at least a rudimentary nervous system, we are discussion systems that respond to changing contingencies much more rapidly than biological evolution. We know, for example, that when the image focused on the human retina is optically inverted, that a person can adapt within a week, and perform complex tasks such as riding a motorcycle. The chief benefit of nervous systems is that they contribute a layer of adaptive evolution that responds much faster than changes to the genome. -------------- Any version of ID consistent with all the evidence is indistinguishable from evolution.

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,14:21    Quote First you asked us how it was possible for natural selection to settle on a blue/green inductive bias when, according to you, a grue/bleen bias would have been equally valid. Now you're telling us that the choice of inductive bias makes no difference.  In a grue/bleen world, a grue/bleen detector has exactly the same structure as a blue/green detector in a blue/green world.  Natural selection gets it right either way by producing the simpler design. Keith, See my response to Bill. I think the crucial point here is that there is a difference between inductive biases and the perceptual system. These are two different cognitive capacities. Saying the detectors have the same structure is to say that the perceptual system is the same. But the inductive biases can still be difference. So the choice of inductive bias makes a difference, but it makes a difference to what the organism expects/predicts, not to what it detects.

keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 23 2008,15:32    Quote (Missing Shade of Blue @ Dec. 23 2008,12:03) Now the supposition is that the detection system is identical for blue-green and grue-bleen creatures. It's not that one of them has a more elaborate system made up of multiple filters and timers or whatever. No, they both have the same detection system... Now where the creatures differ is in their response systems. The blue-green creatures respond to particular detections with green-type expectations about the future. The grue-bleen creatures respond to the same detections with grue type expectations about the future. If you posit different response systems, then Bill's point applies all over again -- but with respect to response instead of perception: Quote In your scenario, green-blue and grue-bleen sensory biases are equally adaptive prior to 2012. Both are adept at responding to the pre-2012 blue green world. Moreover, given how crucial vision is to survival, both mechanisms would be sustained over generations by brutal normalizing selection. Prior to 2012, however, only the components of the grue-bleen system that enable functioning in the pre 2012 blue-green world would be subject to that normalizing selection. Those components and/or computational resources - however simple the final system - that permit grue-bleen perception and hence enable continued success after 2012 would not be subject to normalizing selection prior to 2012 and, absent that selection, would deteriorate and become non-functional. Dude, you're reacting to our comments without thinking things through. Slow down and mull it over for a while. -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

Reciprocating Bill Posts: 4265 Joined: Oct. 2006 (Permalink) Posted: Dec. 23 2008,15:55    Quote (Missing Shade of Blue @ Dec. 23 2008,15:03) Now where the creatures differ is in their response systems... Now my claims were that: (a) These creatures are, ceteris paribus, equally fit prior to 2012. (b) There's no obvious sense in which one creature has all the components of the other plus some more. They have the same detection system and different response systems. Both of these systems will be subject to selection (against other such systems) prior to 2012, but they remain neutral relative to each other until 2012. There is no exploitable asymmetry here until 2012. So given this description, in what sense have I predicted that "just one of these variants will be evident"? You predicted it here:                   Quote ...but the blue-green system has an extra component that anticipates the switch in 2012 from grue to bleen and vice versa. This component is not subject to selection and will deteriorate. In short, having swapped which system projects the most natural predicates, your result is the same. Prior to 2012, one of these variants (by virtue of your starting assumptions) carries features that would enable success post 2012 that the other lacks, but have no impact upon fitness prior to 2012. I'll stipulate that it isn't possible to determine by any metric, prior to that date, which will be more adaptive subsequent to that date, as such efforts will simply re-introduce our biases. However, built into the structure of your thought experiment is the notion that these systems differ in some way that, subsequent to 2012, may result in a marked difference in fitness (and doesn't matter if it is a perceptual or a behavioral difference). Whatever those features are, normalizing selection, prior to 2012, cannot "see" those differentiating features, and therefore cannot sustain them. So the prediction remains that by the time 2012 arrives, either all variants that remain will be able to cope (because there is no actual disjunction, and normalizing selection has sustained those features required to cope with the ongoing, non-disjunct environment) or no variant will cope (because the features required to cope with the disjunction were either never there or have deteriorated). Neither result requires or suggests evolutionary prescience. I don't see that parsing these structures into perceptual and response (behavioral) components and locating the differences in the latter changes this in the least. -------------- Myth: Something that never was true, and always will be. "The truth will set you free. But not until it is finished with you." - David Foster Wallace "Here’s a clue. Snarky banalities are not a substitute for saying something intelligent. Write that down." - Barry Arrington

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,17:28    Keith and Bill, My understanding of Bill's point is that he thinks the grue-bleen inductive agent must have all the same components as the blue-green agent plus something extra. This extra something is not subject to normative selection, so it will eventually deteriorate, leaving a regular blue-green agent. If we redescribe the situation in grue-bleen terms, then the verdict just reverses. Now it is the blue-green agent who has the something extra, and so she will eventually be whittled down to the grue-bleen agent (well, not literally her, but her descendants). In either case, we will end up with the same sort of agent. Anything that could distinguish blue-green agents from grue-bleen ones must be some kind of idle non-adaptive dangler prior to 2012, so its going to disappear. Is this an accurate paraphrase of your argument, Bill? Now I hope you'll bear with me. The next section is kind of long, but I wanted to make sure the issues involved are clear. I feel like all of us are talking past each other a little bit. -- Now I think that there is no reason to think the response systems of the two agents must be additively related in this way. Let me give an example of a really simple blue-green inductive agent. When it sees a bunch of emeralds (pre-2012) it forms the belief "Emeralds are green." What I mean by "forms a belief" in this context is cashed out completely in terms of the following stimulus-response behavior. The agent can bet a certain amount of resources for or against certain questions posed to it by some external tester (a proxy for the environment). Here are the responses to some questions: "Will emerald x be green?" - Bet on yes. "Will emerald x be blue?" - Bet on no. "Will emerald x be grue?" - If x is discovered prior to 2012 bet on yes, else bet on no. "Will emerald x be bleen?" - If x is discovered prior to 2012 bet on no, else bet on yes. Now we have a grue-bleen agent. When faced with the exact same initial set of data as the first agent it forms the belief "Emeralds are grue," cashed out in terms of this response table: "Will emerald x be grue?" - Bet on yes. "Will emerald x be bleen?" - Bet on no. "Will emerald x be green?" - If x is discovered prior to 2012 bet on yes, else bet on no. "Will emerald x be blue?" - If x is discovered prior to 2012 bet on no, else bet on yes. Note that both these agents are formally identical, but they differ in their semantic properties: they respond differently to different external stimuli. One of them will start losing resources in 2012. Now if Bill is right, one/both of these agents has an idle dangler in its response system that will deteriorate before 2012. In this case, the formal identity of both agents means that if one of them has this dangler the other will too (there's no reasonable sense in which the response system of one of these agents is a proper sub-part of the response system of the other). And the plausible candidate for the dangler is the difference in their responses to grue and green questions. This difference will only manifest after 2012, so prior to that it is not subject to normative selection (on Bill's story). This difference in the responses will be whittled away until we are left with creatures who are neutral with respect to these inductive biases, which means they either: (a) make inconsistent bets post-2012 (betting yes on both green and grue for instance), (b) refuse to bet on post-2012 emeralds, or © develop some sort of probabilistic betting strategy that weighs both biases equally (so maybe half the population bets on green and the other half on grue). But all of this relies on a premise: The part of the inductive bias that has to do with grue/green differences is purely additive. Removing it doesn't affect the functioning of the rest of the system. This is a big big assumption, though. It is quite possible that the cheapest sort of response system does distinguish grue and green. In other words, the cheapest way to buy inductive success in the present might involve committing the system to one particular inductive bias in the future. And it might be the case that while the cost of both the blue-green and grue-bleen inductive systems is equivalent prior to 2012 (by hypothesis), they are both cheaper than the sort of inductive system that does not choose between the biases. Now even if you accept all this, you might say, "OK, so maybe it is possible that it's cheaper to have an post-2012 inductive bias rather than none at all. But it's still going to be the case that only one of these biases will survive. By hypothesis, the grue-bleen trait is neutral relative to the blue-green one, so we expect one of them to go to fixation just by random drift." But this is only relevant if the blue-green and grue-bleen populations interbreed. I agree that we should expect a uniform inductive bias within a breeding sub-population.

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,17:32    A quick correction: In the previous post when I was considering the two simple agents I said that the difference between them will only be manifest post-2012. I should have said that the difference between them will only have adaptive consequences post-2012. There will be observable differences between them before then. They'll both make different predictions about what will happen after 2012, for instance.

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,17:57    BTW, I apologize to all the people I haven't yet responded to. It's not that I'm ignoring your posts because I think they're stupid (or, conversely, unanswerable). I'm posting stuff on here in between bouts of trying to get a chapter of my dissertation ready. I'm already spending way more time on here than I probably should, so you'll excuse me for shying away from becoming embroiled in more than one discussion at a time. Although so far I haven't done such a great job in the shying away department.

Reciprocating Bill Posts: 4265 Joined: Oct. 2006 (Permalink) Posted: Dec. 23 2008,19:18    Quote (Missing Shade of Blue @ Dec. 23 2008,18:28) Let me give an example of a really simple blue-green inductive agent. When it sees a bunch of emeralds (pre-2012) it forms the belief "Emeralds are green." What I mean by "forms a belief" in this context is cashed out completely in terms of the following stimulus-response behavior. The agent can bet a certain amount of resources for or against certain questions posed to it by some external tester (a proxy for the environment). Here are the responses to some questions: "Will emerald x be green?" - Bet on yes. "Will emerald x be blue?" - Bet on no. "Will emerald x be grue?" - If x is discovered prior to 2012 bet on yes, else bet on no. "Will emerald x be bleen?" - If x is discovered prior to 2012 bet on no, else bet on yes. Now we have a grue-bleen agent. When faced with the exact same initial set of data as the first agent it forms the belief "Emeralds are grue," cashed out in terms of this response table: "Will emerald x be grue?" - Bet on yes. "Will emerald x be bleen?" - Bet on no. "Will emerald x be green?" - If x is discovered prior to 2012 bet on yes, else bet on no. "Will emerald x be blue?" - If x is discovered prior to 2012 bet on no, else bet on yes. Note that both these agents are formally identical, but they differ in their semantic properties: they respond differently to different external stimuli. One of them will start losing resources in 2012. Your first paragraph does accurately describe my position. Otherwise, I don't follow. Using your scheme of question and response (which I don't much like), the blue-green agent would be represented thusly: "Will emerald x be green?" - Bet on yes. "Will emerald x be blue?" - Bet on no. "Will emerald x be grue?" - No meaning to a system with blue-green predicates. "Will emerald x be bleen?" - No meaning to a system with blue-green predicates. The simplest possible blue-green system shaped by "experience" (selection) in an exclusively blue-green world would lack the facilities to make the "if date < 2012 then predict green else predict blue" decisions you describe. Hence it is not formally equivalent to the grue-bleen system you subsequently describe, does does need something equivalent to an if-then-else decision logic that tests the date prior to every prediction. Which facilities are the very "dangler" you describe, features that must be lost even in a grue-bleen world because invisible to normalizing selection prior to 2012. -------------- Myth: Something that never was true, and always will be. "The truth will set you free. But not until it is finished with you." - David Foster Wallace "Here’s a clue. Snarky banalities are not a substitute for saying something intelligent. Write that down." - Barry Arrington

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,21:57    Quote The simplest possible blue-green system shaped by "experience" (selection) in an exclusively blue-green world would lack the facilities to make the "if date < 2012 then predict green else predict blue" decisions you describe. Hence it is not formally equivalent to the grue-bleen system you subsequently describe, does does need something equivalent to an if-then-else decision logic that tests the date prior to every prediction. Which facilities are the very "dangler" you describe, features that must be lost even in a grue-bleen world because invisible to normalizing selection prior to 2012. This is the part I disagree with. You think that there is something about the world being blue-green that will make blue-green inductive agents simpler than grue-bleen ones, prior to 2012 (grue-bleen agents would need an extra dangler). Presumably you also agree that if the world were actually grue-bleen then grue-bleen agents would be simpler than blue-green ones prior to 2012. But what does it mean for the world to be blue-green vs. grue-bleen? It just means that "blue" remains a stable and lawlike predicate (and mutatis mutandis for grue). Things that are naturally blue do not change their color discontinuously and without cause. But if this is all it means for a world to be blue-green, then we could change a blue-green world to a grue-bleen world without changing anything that happens before 2012. Just switching the colors of objects post-2012 without touching anything before 2012 should give us a grue-bleen world. In other words, we can have a grue-bleen world and a blue-green world that look just like each other up to 2012 and only differ afterwards. Right? Seems right to me. But you say it's wrong. According to you, you can't change a blue-green world to a grue-bleen one without changing some stuff prior to 2012. Namely, you have to change the construction of inductive agents, because you don't think we could end up with simpler grue-bleen creatures in a blue-green world and vice versa. Which means you think that information about the natural structure of the world (whether its blue-green or grue-bleen) is available prior to 2012. I don't see how this could be the case (if we don't assume the correctness of our or evolution's inductive biases). Properties don't come tagged with labels reading "this is natural". The naturalness (at least, the projectibility) of green vs. grue consists solely in how objects behave after 2012. In a naturally green world they stay green, while in a grue world they switch to blue. So it seems to me that you must either maintain that green creatures must be simpler than grue ones independently of the structure of the world (its blue-greenness or grue-bleenness), in which case we're back to the question of a language-independent notion of simplicity. Or you should agree that there is no obvious reason to think that blue-green creatures will be simpler even in an exclusively blue-green world. [Here's where I go schizophrenic again. While I think its wrong to say that blue-green creatures will be favored in a naturally blue-green world, it is correct to say blue-green creatures will be favored in a world where the evolutionary algorithm has a blue-green inductive bias. There's no non-biased reason to thing the bias of the algorithm must track the structure of the world, but that's just the general Humean problem of induction, which is why I abandoned that line of inquiry.]

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 23 2008,22:09    I note with dismay that we've crossed 100 posts on this thread. I've really been posting way too much so I'm going to try to cut back and get some actual work done. I'm going to read what people have to say and I might be irresistibly drawn to respond, but this is my official request not to be offended if I don't reply for a while. Discussing this has certainly been illuminating and enjoyable for me, and I appreciate y'all being gentle. I came in to this deeply puzzled and I leave significantly less puzzled. That's a lot more than you can reasonably expect from your usual internet forum discussion. Have a great holiday season, everybody. I hope baby Jesus brings you lots of presents.

Louis Posts: 6436 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,03:50    Quote (Missing Shade of Blue @ Dec. 24 2008,04:09) [SNIP] I hope baby Jesus brings you lots of presents. Wait, does this mean Santa's not real? Louis -------------- Bye.

keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,03:55    Quote (Missing Shade of Blue @ Dec. 23 2008,19:57) According to you, you can't change a blue-green world to a grue-bleen one without changing some stuff prior to 2012. Namely, you have to change the construction of inductive agents, because you don't think we could end up with simpler grue-bleen creatures in a blue-green world and vice versa. Which means you think that information about the natural structure of the world (whether its blue-green or grue-bleen) is available prior to 2012. I don't see how this could be the case (if we don't assume the correctness of our or evolution's inductive biases). MSB, That's not what Bill is saying. I think I see the source of the confusion.  You've been talking about changing the wavelength of light reflected by emeralds in 2012 but also about changing the wavelength of light responded to by the detectors in 2012. The confusion will go away if you carefully define what you mean by a "grue-bleen world". In a grue/bleen world: 1a. What wavelength of light will an emerald reflect before 2012? 1b. What wavelength of light will an emerald reflect after 2012? 2a. What wavelength of light will detector A respond to before 2012? 2b. What wavelength of light will detector A respond to after 2012? 3a. What wavelength of light will detector B respond to before 2012? 3b. What wavelength of light will detector B respond to after 2012? If the answers to the a's match the answers to the corresponding b's in all cases, then you obviously have a blue/green world, because nothing changes in 2012. If the answers to the a's differ from the answers to the b's in all cases, then you have a world that is indistinguishable from a blue/green world (neglecting the possibility of direct or indirect wavelength measurements which we are not considering here). Everything changes in 2012, but the changes cancel out so that nobody notices. Let's call this a "quasi-blue/green world". In a true grue/bleen world, either the answers to 1a vs. 1b will differ, or the answers to 2a vs. 2b and 3a vs. 3b will differ. When 2012 arrives, the change will be obvious to the inhabitants of the world. The confusion stems from not consistently talking about a true grue/bleen world. Part of the time you've been talking about the quasi-blue/green world instead. If you ponder this carefully, I think you'll see that evolution will select the simpler detector and the simpler response in all of the possible worlds, and that no prescience is involved. The simple solution is favored because it is simple while being equally adaptive. Natural selection is not "guessing" the correct inductive bias for our (presumably) blue/green world, and so the mystery that you raised in the beginning of this discussion is not a mystery at all. -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,04:04    Quote (Louis @ Dec. 24 2008,01:50)   Quote (Missing Shade of Blue @ Dec. 24 2008,04:09) [SNIP] I hope baby Jesus brings you lots of presents. Wait, does this mean Santa's not real? Of course Santa is real, dear.  Now run along, Louis, the grownups are talking. -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

Louis Posts: 6436 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,05:01    Quote (keiths @ Dec. 24 2008,10:04) Quote (Louis @ Dec. 24 2008,01:50)   Quote (Missing Shade of Blue @ Dec. 24 2008,04:09) [SNIP] I hope baby Jesus brings you lots of presents. Wait, does this mean Santa's not real? Of course Santa is real, dear.  Now run along, Louis, the grownups are talking. Harsh and unfair! Well done. Louis -------------- Bye.

Patashu Posts: 6 Joined: Oct. 2007 (Permalink) Posted: Dec. 24 2008,05:16    Okay, just butting in quickly. Hm... If we lived in a universe where bleen, grue and their respective sensors were the norm, and blue/green sensors as we know it were the ones that required an adjustment from grue/bleen sensors (presumably by a timer to reverse it out)...I'm pretty sure it'd be functionally equivalent to our universe, since the normal people would see the same colours before and after and the deviants would be the ones seeing them change. Am I in the wrong here?

Reciprocating Bill Posts: 4265 Joined: Oct. 2006 (Permalink) Posted: Dec. 24 2008,05:48    Quote (Missing Shade of Blue @ Dec. 23 2008,22:57) You think that there is something about the world being blue-green that will make blue-green inductive agents simpler than grue-bleen ones, prior to 2012 (grue-bleen agents would need an extra dangler). Presumably you also agree that if the world were actually grue-bleen then grue-bleen agents would be simpler than blue-green ones prior to 2012. No, I've saying something quite different. I'm saying that a blue-green world and an actual grue-bleen world prior to 2012 subject both agents to identical normalizing selection prior to 2012, selection that sustains blue-green predication but fails to support grue-bleen predication were it present at the outset. This doesn't make blue-green inductive agents simpler than grue-bleen ones; rather, it renders grue-bleen agents functionally similar to blue-blue green ones, in that they inevitably become capable of blue-green predication only. Note that I am asserting exactly the same selection pressures (prior to 2012) in both worlds. This predicts that, come 2012, either all agents succeed because there is no disjunction, or all fail because there is a disjunction but no agents remain that can cope with it - either they were always blue-green agents, or they were orginally grue-bleen agents that have come to functionally resemble blue-green agents. Neither outcome suggests evolutionary prescience. -------------- Myth: Something that never was true, and always will be. "The truth will set you free. But not until it is finished with you." - David Foster Wallace "Here’s a clue. Snarky banalities are not a substitute for saying something intelligent. Write that down." - Barry Arrington

Quack Posts: 1961 Joined: May 2007 (Permalink) Posted: Dec. 24 2008,09:26    FWIMBW: Let's assume that it is true that evolution works by extinction of the less fit. In the absence of predators, poisons, dangers - and abundant supply of food, mating partners and so on +++ - everyone is fit to survive. Until disaster strikes or the inevitable bottleneck occurs. Isn't that what the records show? -------------- Rocks have no biology.               Robert Byers.

keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,09:38    Quote (Patashu @ Dec. 24 2008,03:16) Okay, just butting in quickly. Hm... If we lived in a universe where bleen, grue and their respective sensors were the norm, and blue/green sensors as we know it were the ones that required an adjustment from grue/bleen sensors (presumably by a timer to reverse it out)...I'm pretty sure it'd be functionally equivalent to our universe, since the normal people would see the same colours before and after and the deviants would be the ones seeing them change. Am I in the wrong here? Patashu, That's what I referred to as the "quasi-blue/green world" in this comment. -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

dvunkannon Posts: 1377 Joined: June 2008 (Permalink) Posted: Dec. 24 2008,09:48    Quote (Louis @ Dec. 24 2008,04:50) Quote (Missing Shade of Blue @ Dec. 24 2008,04:09) [SNIP] I hope baby Jesus brings you lots of presents. Wait, does this mean Santa's not real? Louis childhood Xmas induction FAIL -------------- I’m referring to evolution, not changes in allele frequencies. - Cornelius Hunter I’m not an evolutionist, I’m a change in allele frequentist! - Nakashima

dvunkannon Posts: 1377 Joined: June 2008 (Permalink) Posted: Dec. 24 2008,09:50    On the bus into work this morning, it struck me that a world of mixed green and grue critters is just exaptation waitng to happen. Then I fell asleep again. -------------- I’m referring to evolution, not changes in allele frequencies. - Cornelius Hunter I’m not an evolutionist, I’m a change in allele frequentist! - Nakashima

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 24 2008,14:19    Keith and Bill, Yeah, I see the point about the quasi-grue/bleen world. If we change the properties of the external world and the structure of the agents at the same time we're creating a world that is not detectably different from our own. In fact, it's basically just redescribing our own world using a different set of predicates. I should have been tipped off by the formal equivalence of the two inductive agents I described. If they're truly formally equivalent then the best way of describing the situation is not that theyre picking out different properties but that they're using different languages (which are grue/green inverts of each other) to pick out the same properties. So yeah, I accept that true grue-bleen agents, ones who make materially different predictions post-2012, would have to be structurally quite different from blue-green ones. Would they have to be more complex? This is the tricky part for me. Whatever their construction, there will be some representation in which it will be simpler to describe the grue-bleen agent. There is no purely syntactic sense in which this representation is unnatural. But maybe there is a physical sense in which it would be unnatural. Possibly such a representation would carve up physical objects in ways that are just objectively complex. I'll think about it. But yeah, I was on the wrong track, so thanks for pointing that out and being patient.

keiths Posts: 2195 Joined: Jan. 2006 (Permalink) Posted: Dec. 24 2008,16:51    Quote (Missing Shade of Blue @ Dec. 24 2008,12:19) Would they [grue/bleen agents] have to be more complex? This is the tricky part for me. Whatever their construction, there will be some representation in which it will be simpler to describe the grue-bleen agent. There is no purely syntactic sense in which this representation is unnatural. But maybe there is a physical sense in which it would be unnatural. Possibly such a representation would carve up physical objects in ways that are just objectively complex. I'll think about it. I still think that grue-bleen agents are objectively more complex, even apart from physical considerations.  There is inescapably a time element embedded in the concepts of grue and bleen. Grue is "green if before 2012 and blue afterward'; green is just green, timelessly. If you try to avoid this by using grue and bleen as primitives, then you've simply moved the complexity into the definitions of the primitives themselves.  But then the primitives become time-dependent, which makes them more complex than the primitives "blue" and "green", which are not.   By the way, can you tell us anything about your dissertation?  (Feel free not to answer if you're concerned about compromising your anonymity.) -------------- And the set of natural numbers is also the set that starts at 0 and goes to the largest number. -- Joe G Please stop putting words into my mouth that don't belong there and thoughts into my mind that don't belong there. -- KF

Missing Shade of Blue Posts: 62 Joined: Dec. 2008 (Permalink) Posted: Dec. 24 2008,17:58    Keith, I don't know if I want to go into too much detail about it, but I would be happy to give a broad description of my work. The dissertation is in the foundations of statistical mechanics. Slightly more specifically, I'm investigating the physical grounds for the success of phase averaging (the process by which thermodynamic quantities are calculated by averaging over functions on phase space under some probability distribution). The textbook justification for this is ergodicity (crudely, the idea that thermodynamic systems follow a trajectory that passes arbitrarily close to every point in phase space), but that is unsatisfactory for a number of reasons, so I'm exploring the possibility of a non-ergodic approach to the foundations of the theory.

Cubist Posts: 558 Joined: Oct. 2007 (Permalink) Posted: Dec. 24 2008,18:35    What's so special about the year 2012? Let's generalize this "grue/bleen" business, and say that an object is "grue (XXXX)" if it's green until the year XXXX, and blue thereafter; similarly, "bleen (XXXX)" objects are blue until the year XXXX, and green thereafter. (I hope I got the switches set correctly...) Obviously, some objects have been grue (2007), because we humans do have a tendency to change the appearance of things, and it would be a rather improbable state of affairs if no green object(s) whatsoever were painted blue during the year 2007. Likewise, natural processes can and do alter the appearance of objects, so it's hardly implausible that there might be at least one naturally-occurring instance of a grue (2007) object. However, it's worth noting that the above paragraph is built on the implicit presumption that an object's color remains stable unless some physical process alters that color. And the whole "grue/bleen" schtick, as best I understand it, explicitly denies that there is any intrinsic stability to an object's color -- the "grue/bleen" schtick explicitly asserts that an object's color can change, just because. But thus far, we do not have any actual examples of objects whose color changed "just because"! Color changes because humans messed with the color, sure; color changes because some physical process messed with the color, sure; color changes just because, not so much. Ignoring color-changes with known causes, because those color-changes aren't relevant to this "grue/bleen" schtick in the first place, there are no grue (XXXX) objects, or bleen (XXXX) objects, where 'XXXX' is any year before the present. In principle, as a hypothetical proposition, it's entirely possible that any object which has proved itself to be green rather than grue (2007) might turn out to be grue (2008), or grue (2009), or yada yada yada... but how does this differ from the hypothetical proposition that the Sun might not rise tomorrow, or that gravity might switch over to a repulsive force next year? In sum: As a practical matter, this "grue/bleen" schtick is basically mental masturbation. If that's the sort of thing you enjoy doing, feel free; just don't expect anybody else to take it seriously.

Nerull Posts: 317 Joined: June 2007 (Permalink) Posted: Dec. 24 2008,21:42    Of course, since grues only appear when it is pitch black, do they really have a color? And why do they find adventurers so tasty? Sorry, I haven't been able to get Zork out of my head since this discussion started.   -------------- To rebut creationism you pretty much have to be a biologist, chemist, geologist, philosopher, lawyer and historian all rolled into one. While to advocate creationism, you just have to be an idiot. -- tommorris

Reciprocating Bill Posts: 4265 Joined: Oct. 2006 (Permalink) Posted: Dec. 25 2008,09:00    Quote (Nerull @ Dec. 24 2008,22:42) Of course, since grues only appear when it is pitch black, do they really have a color? And why do they find adventurers so tasty? The words of a menacing troll. (My sword is glowing with a faint bleen glow...) -------------- Myth: Something that never was true, and always will be. "The truth will set you free. But not until it is finished with you." - David Foster Wallace "Here’s a clue. Snarky banalities are not a substitute for saying something intelligent. Write that down." - Barry Arrington

olegt Posts: 1405 Joined: Dec. 2006 (Permalink) Posted: Dec. 25 2008,09:35    Quote (Missing Shade of Blue @ Dec. 24 2008,17:58) Keith, I don't know if I want to go into too much detail about it, but I would be happy to give a broad description of my work. The dissertation is in the foundations of statistical mechanics. Slightly more specifically, I'm investigating the physical grounds for the success of phase averaging (the process by which thermodynamic quantities are calculated by averaging over functions on phase space under some probability distribution). The textbook justification for this is ergodicity (crudely, the idea that thermodynamic systems follow a trajectory that passes arbitrarily close to every point in phase space), but that is unsatisfactory for a number of reasons, so I'm exploring the possibility of a non-ergodic approach to the foundations of the theory. Sounds like you're a mathematical physicist, Missing Shade of Blue.  What's wrong with ergodicity?  Phase-space averaging seems to describe time-averaged properties of systems in thermal equilibrium pretty well.   (I hope I am not derailing the thread. ) -------------- If you are not: Galapagos Finch please Logout »

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