In Part II we saw that by and large all measurable indicators of human welfare show improvement. Indeed, it is difficult to contest these indicators. But maybe we are living on borrowed time.

This is the typical objection we hear from organizations such as Worldwatch Institute:

In other words, it may be true that things have been going well. But actually, things have been going too well. This development cannot continue. The natural foundations will collapse. With an oft-repeated metaphor, we are told: “Just as a continuously growing cancer eventually destroys its life-support systems by destroying its host, a continuously expanding global economy is slowly destroying its host – the Earth's ecosystem.”

Professor Ehrlich reiterates the same basic idea: economists are fond of pointing out that GDP and food availability per capita grow and grow. “But there is a fatal flaw in this argument: it is roughly equivalent to bragging about one’s ability to write a bigger check each month, while paying no attention to the balance in the account.”