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Originally Posted by Gullible Jones
If there's a future human civilization, it has to have a history. Some of the total number of people born in its history would have to be born relatively early during that history - they'd "draw the short straw", as it were.
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Ah, OK. This doesn't work, because (as Ken says) Carter's argument is probabilistic: it states that there's a 95% chance of extinction after
x number of lives. Such a prediction accepts, indeed
stipulates, that it will be wrong on 5% of occasions (ie, for those born early in human history).
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Originally Posted by snarkophilus
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Imagine that two big urns are put in front of you, and you know that one of them contains ten balls and the other a million, but you are ignorant as to which is which. You know the balls in each urn are numbered 1, 2, 3, 4 ... etc. Now you take a ball at random from the left urn, and it is number 7. Clearly, this is a strong indication that that urn contains only ten balls. [...]
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This isn't true. The fact that you chose ball number 7 doesn't say anything about which urn is which. |
Unfortunately, this "illustration" seems to have been written by someone who doesn't understand Carter, or doesn't understand how to construct a good illustrative analogy: it's utterly misleading about how Carter's argument works.
There's no choice of urns. There's a
single urn, which contains an
unspecified quantity of consecutively numbered balls - anything from 10 to a million. We blindly select a ball, and find it's number 7. This is more likely to occur if the urn contains a small number of balls than a large number of balls. In fact, we can deduce a 95% confidence interval for how many balls the urn contains. Implicit in that calculation is the prediction that 5% of the time the urn will actually contain
more balls than the upper limit of our confidence interval (assuming I've constructed a one-tailed confidence interval).
Grant Hutchison