To me, that version of the doomsday question is extremely unconvincing for a very different reason. It is using only the most basic (single number, N) aspect of the available data. We could go one step more sophisticated and get the number of people born last year and extrapolate that number of annual births out to eternity. Or we could go yet another step more sophisticated and fit an exponential to the births per year graph to extrapolate instead. Presumably we could go much further, fitting ever more complex models to a wider set of available data. Perhaps even trying to include models of the Earth’s calorific budget or the likelihood of nuclear war.
Its not clear to me why we would put any credence in the doomsday argument (take N, approximately double it) specifically, out of all the available models.
It’s not meant to be convincing, since it doesn’t make any argument. It’s a version of the question.
You can obviously make models of the future, using whatever hypotheses you like. Those models then should be weighted by complexity of hypotheses and credence that they will accurately reflect the future based partly on retrodiction of the past, and the results will modify the very broad distribution that you get by taking nothing but birth rank. If you use a SSA evidence model, then this broad distribution looks something like P(T > kN) ~ 1/k.
If you take all the credible future models appropriately weighted and get a relatively low credence of doomsday before another N people come into existence, then the median of the posterior distribution of total people will be greater than that of the doomsday prior distribution.
To me, that version of the doomsday question is extremely unconvincing for a very different reason. It is using only the most basic (single number, N) aspect of the available data. We could go one step more sophisticated and get the number of people born last year and extrapolate that number of annual births out to eternity. Or we could go yet another step more sophisticated and fit an exponential to the births per year graph to extrapolate instead. Presumably we could go much further, fitting ever more complex models to a wider set of available data. Perhaps even trying to include models of the Earth’s calorific budget or the likelihood of nuclear war.
Its not clear to me why we would put any credence in the doomsday argument (take N, approximately double it) specifically, out of all the available models.
It’s not meant to be convincing, since it doesn’t make any argument. It’s a version of the question.
You can obviously make models of the future, using whatever hypotheses you like. Those models then should be weighted by complexity of hypotheses and credence that they will accurately reflect the future based partly on retrodiction of the past, and the results will modify the very broad distribution that you get by taking nothing but birth rank. If you use a SSA evidence model, then this broad distribution looks something like P(T > kN) ~ 1/k.
If you take all the credible future models appropriately weighted and get a relatively low credence of doomsday before another N people come into existence, then the median of the posterior distribution of total people will be greater than that of the doomsday prior distribution.