Re: Objection to the Doomsday Argument?

Hal Finney (
Mon, 17 Aug 1998 08:47:36 -0700

Nick Bostrom, <>, writes:
> Do you know which second you were born? If not, and you were asked to
> guess, you could repond with a probability distribution over a range
> of seconds. The same with minutes; and it's easy to imagine a
> situation where you suffer from amnesia and you are not even sure
> what year you were born. (That is actually quite common among old
> people in some parts of the world where there were no public records
> of births. That's why claims for longevity records tend to come
> from obscure places.) If you can be uncertain what year, then not
> what decade? Are there any clear limits to how far we can push this
> reasoning?

I think there are limits, although not necessarily sharp ones. I cannot be uncertain about what century I was born in, not if I have enough of my memories to even be able to know what happened in various centuries.

For one thing, I have memories of 20th century events, so I cannot have been born earlier than the 20th century. I have no memories whatsoever about 21st century events, so assuming that the only thing erased from my memory was my birth date, then I must have been born in the 20th century.

Similarly I have no personal memories of events from before the decade I was born, but I do have personal memories of events from that decade and later ones. Of course my younger memories are hazier and less certain, but I should be able to narrow down my date of birth to within about a five to ten year period just based on what I remember experiencing.

This amount of uncertainty is not enough to drive the DA assumption that I might have been born at any time in human history. I am a product of my times in a very fundamental way. I would be a very different person if I were born in the 17th or 23rd centuries.