This morning, Lebron James' attempt to justify his lifestyle got me to thinking about people. We often hear that the world has too many people, but to many highly trained economists (he he he), population growth is the key to economic growth.
First generation endogenous growth models (eg. Romer JPE 1990) had the implication that long run growth in income per capita was proportional to the number of researchers in the ideas sector. In this case long run growth was possible with a fixed population and policies that increased the number of researchers had growth effects.
However, Charles Jones (QJE 1995) showed that, over the last 40 years, the number of researchers had grown dramatically while growth rates were largely unchanged, so economists modified the Romer model to reduce the productivity of workers in the ideas sector. In this endogenous growth without scale effects (or semi-endogenous growth) model, long run growth in income per capita is proportional to population growth.
From this point of view, Sarah Palin has it right and Tyler (and me and Mrs. Angus) have it exactly wrong! It would be better to take pro-environment steps that did not work to reduce population growth.