> Sustainability means keeping the population at a consistent level. Otherwise, exponential growth means that the planet is eventually covered in humans to a depth of 50ft, and nobody wants that.
But the third myth section covers your proposed malthusean explosion, and declares that it's not a valid concern.
"In Southeast Asia and Latin America, average fertility dropped from six or seven children per woman to two or three in a single generation, thanks in large measure to the modern contraceptives available by the 1960s."
The article is talking about our world, which is one in which contraceptives are widely available. We can't really look at alternate realities in which there are rich countries with no contraceptives and see how their birth rates fared, but I see no reason to assume they would drop, because people will still have sex.
The Malthusian explosion is not a valid concern precisely because of contraception.
But the third myth section covers your proposed malthusean explosion, and declares that it's not a valid concern.