Re: Leslie's "The End of the World"

Robin Hanson (
Fri, 14 Aug 1998 20:21:15 -0700 (PDT)

Nick B. writes:
>> I reread Leslies book on this issue last night, and object to
>> putting bios and postbios into the same ref class in exactly the way
>> that Leslie envisions one might object:
>> It might perhaps be complained that making the reference class into
>> humans-after-splitting-away-from-Neanderthals would be coming too
>> near to imitating the man who makes his reference class into
>> people-born-as-late-as-himself-or-later [p. 261, The End of the World]
>The complaint that Leslie is refering to is that the reference class
>should not be unduely *narrowed*, that it would be wrong to leave out
>the pre-Neanderthal people. What you are saying is that the reference
>class should not be *widened* to include postbios. So why do you say
>that you object in exactly the same way as Leslie envisions? As far
>as I know, Leslie has never considered ruling out postbios from the
>reference class on the ground that they would be too different.

I'm saying that having a relatively narrow/strict cut in early times and a relatively wide/generous cut in later times constitutes a bias, which will make us earlier in the rank order than an unbiased reference class. This bias will make the total population seem smaller than otherwise.