> In that case there are easy answers. Firstly if we dramatically increase
> our lifespans and reduce our birth-rates, then we could be born half-way
> through the human race and still have billions of years to go.
If this were right, it would in itself be an interesting result. It would seem to refute the idea that in the future there will be a great many intelligent beings.
But there is a version of the doomsday argument that bites on this possibility too. Rather than counting the number of observers, you should (arguably) count the number of "observer-moments" - i.e. timesegments of observers. In that case you get little respite from assuming that birth rates will drop drastically.
> AI is hard and uploads are easy then most future life will originate from uploaded humans.
>In that case, even though the vast majority of life has
> yet to be "born" (i.e. forked off from another upload) many of those SIs
> will probably originate from people already alive; we'd only be half-way
> through the *organic* human race
But what's so relevant about being organic?
> because any SIs would have memories of
> once being organics.
> In fact I could take this argument to extremes and point out that since
> I'm currently inhabiting this body I must be the person fated to become
> the first SI and take over the universe (if you believe that is inevitable).
I'm afraid you've lost me here.