Doomsday Thereom

[eldynamite]

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Apart from being presented badly there is no particular fallacy in his argument. To get his absurd conclusion he had to claim that the random number assigned to him was a specific value, 50 billion in fact. That is the problem he had no right to do this.


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No particular fallacy? Surely, it cannot be seriously maintained that the argument is sound. Common sense should tell you that an abstract mathematical argument cannot make valid predictions about the fate of humanity.

Let's suppose that this Doomsday Argument (DA) had been advanced by somebody every hundred years since the first humans emerged perhaps a hundred thousand years ago. We cannot tell if the DA is valid today, but it has failed 999 times in a row, so by historical standards it doesn't have much going for it.

Getting back to the point that our hero has no right assign a particular number to himself (50 billion), isn't it possible in principle to determine how many people were born before you? I'm not sure why the practical difficulty in doing so has much bearing on the argument.

Let me try to explain my point a bit more clearly. I'll concede that N is almost assuredly finite, and that it is possible to choose an integer at random between 1 and N. However, asserting that 50,294,771,302 (or whatever) is a random integer is simply wrong, because there is no way to generate a number at random without knowing what N is. In the vernacular, "random" is frequently used to describe something undistinguished. Now, 50,294,771,302 looks pretty undistinguished (maybe not -- remember 1729?) but that doesn't make it random in the mathematical sense. The DA as described by jimdmcevoy is based on the assumption that one's place in the line-up of all humans is random, but since there is no way to generate a random integer between 1 and N, where N is unknown, this assumption is simply false. By assuming that 50,294,771,302 is random, he assumes something about the likely value of N. The DA is a circular argument.


Tim