rmiller wrote:

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At 02:45 PM 6/7/2005, Jesse Mazer wrote: (snip)Of course in this example Feynman did not anticipate in advance whatlicence plate he'd see, but the kind of "hindsight bias" you are engagingin can be shown with another example. Suppose you pick 100 random wordsout of a dictionary, and then notice that the list contains the words"sun", "also", and "rises"...as it so happens, that particular 3-word"gestalt" is also part of the title of a famous book, "the sun also rises"by Hemingway. Is this evidence that Hemingway was able to anticipate theresults of your word-selection through ESP? Would it be fair to test forESP by calculating the probability that someone would title a book withthe exact 3-word gestalt "sun, also, rises"? No, because this would betailoring the choice of gestalt to Hemingway's book in order to make itseem more unlikely, in fact there are 970,200 possible 3-word gestalts youcould pick out of a list of 100 possible words, so the probability that abook published earlier would contain *any* of these gestalts is a lothigher than the probability it would contain the precise gestalt "sun,also, rises". Selecting a precise target gestalt on the basis of the factthat you already know there's a book/story containing that gestalt is anexample of hindsight bias--in the Heinlein example, you wouldn't havechosen the precise gestalt of Szilard/lens/beryllium/uranium/bomb from along list of words associated with the Manhattan Project if you didn'talready know about Heinlein's story.RM wrote:In two words: Conclusions first.Can you really offer no scientific procedure to evaluate Heinlein's story?At the cookie jar level, can you at least grudgingly admit that the word"Szilard" sure looks like "Silard"? Sounds like it too. Or is that acoincidence as well? What are the odds. Should be calculable--how manystories written in 1939 include the names of Los Alamos scientists inconjunction with the words "bomb" , "uranium. . ."You're shaking your head. This, I assume is already a done deal, for you.And that, in my view, is the heart of the problem. Rather than swallowhard and look at this in a non-biased fashion, you seem to be glued to theproposition that (1) it's intractable or (2) it's not worth analyzingbecause the answer is obvious.

`I think you misunderstood what I was arguing in my previous posts. If you`

`look them over again, you'll see that I wasn't making a broad statement`

`about the impossibility of estimating the probability that this event would`

`have happened by chance, I was making a specific criticism of *your* method`

`of doing so, where you estimate the probability of the particular "gestalt"`

`of Szilard/lens/beryllium/uranium/bomb, rather than trying to estimate the`

`probability that a story would anticipate *any* possible gestalt associated`

`with the Manhattan Project. By doing this, you are incorporating hindsight`

`knowledge of Heinlein's story into your choice of the "target" whose`

`probability you want to estimate, and in general this will always lead to`

`estimates of the significance of a "hit" which are much too high. If you`

`instead asked someone with no knowledge of of Heinlein's story to come up`

`with a list of as many possible words associated with the Manhattan Project`

`that he could think of, then estimated the probability that a story would`

`anticipate *any* combination of words on the list, then your method would`

`not be vulnerable to this criticism (it might be flawed for other reasons,`

`but I didn't address any of these other reasons in my previous posts).`

Look over the analogy I made in my last post again: Suppose you pick 100 random words out of a dictionary, and then notice that the list contains the words "sun", "also", and "rises"...as it so happens, that particular 3-word "gestalt" is also part of the title of a famous book, "the sun also rises" by Hemingway. Is this evidence that Hemingway was able to anticipate the results of your word-selection through ESP? Would it be fair to test for ESP by calculating the probability that someone would title a book with the exact 3-word gestalt "sun, also, rises"? No, because this would be tailoring the choice of gestalt to Hemingway's book in order to make it seem more unlikely, in fact there are 970,200 possible 3-word gestalts you could pick out of a list of 100 possible words, so the probability that a book published earlier would contain *any* of these gestalts is a lot higher than the probability it would contain the precise gestalt "sun, also, rises".

`To simplify things even further, let's say you simply make a list of ten`

`random numbers from 1 to 100, and before you make the list I make the`

`prediction "the list will contain the numbers 23 and 89". If it turns out`

`that those two numbers are indeed on your list, what is the significance of`

`this result as evidence for precognition on my part? Your method would be`

`like ignoring the other 8 numbers on the list and just finding the`

`probability that I would hit the precise target of "23, 89" by chance, which`

`(assuming order doesn't matter) would be only about a 1 in 5025 shot, if my`

`math is right. But the probability that both the numbers I guess will be`

`*somewhere* on the list of ten is significantly higher--I get that the`

`probability of this would be about 1 in 121. So if this experiment is done`

`in many alternate universes, then if in fact I have no precognitive`

`abilities, in about 1 in 121 universes, both numbers I guess will happen to`

`be on your list by luck. But then if you used the method of tailoring the`

`choice of target to my guess, in each such universe you will conclude that I`

`only had a 1 in 5025 chance of making that guess by chance. Clearly, then,`

`you get bad conclusions if you use hindsight knowledge to tailor the choice`

`of target to what you know was actually guessed in this way. But it's also`

`clear that this example is sufficiently well-defined that I would have no`

`general objection to estimating the probability that my "hit" could have`

`occurred by chance, it's just that the correct answer is 1 in 121, not 1 in`

`5025.`

Jesse