[T-hawk]

Right. The fallacy of Malthusianism is that all those extra people turn out to have a knack for producing the stuff they need. Of course there's an ultimate limit, of the total insolation energy to Earth or maybe a Dyson sphere, but there are many multiples of headroom compared to Earth's current population and productivity.

[lotharbot]

The other fallacy of Malthusianism is that people (like other life forms) breed faster when there's surplus, and slower when there's not. Thus, as the population approaches the resource limit, it grows more slowly.

See, for example, Verhulst's mathematical description of population growth [0], written in response to Malthus. You can chart the data and see a very clear divergence from Malthus' expectations [1].

[0] http://en.wikipedia.org/wiki/Logistic_function#In_ecology:_m...

[1] for example, http://www.growth-dynamics.com/articles/Kurzweil_files/image... -- the higher curve is exponential, the lower curve is logistic