capitalism and eternal growth

[The Mikado]

As far as the economic growth being necessary for the capitalist economic system argument goes, I've only heard it in relation to the massive population boom of the past two hundred years attributable to industrialization and the massive increase of agricultural output.  The human population two hundred years ago was a seventh what it is today, it stands to reason that we had to expand our global economy at least sevenfold (in actuality much more than that) to keep the standard of living from plummeting too far. 

As the industrial world allows for a higher and higher maximum population, especially agricultural production needs to expand at a similar absurd rate to prevent a Malthusian crisis, but fewer and fewer people are needed to grow more and more crops, so there also has to be a large and ever-expanding field of non-agricultural employment available to ensure that as the population rose, unemployment wouldn't shoot up along with it.

As ag points out, population growth is slowing and might well peak in the latter part of the coming century, at which point the above dynamic loses some of its meaning.