Following up to my previous post proposing a cap and trade system to curb population growth, I've now been convinced by the people at Reason.com that there's a good chance we don't actually need to impose a limit.

If we assume that we have the political strength to impose a global population growth curb, then we can probably also assume that we have the political strength to protect the Earth's ecosystems from people, regardless of how many people there are.

If that is the case, then the remaining issue at stake - in deciding whether to impose a curb or not - is whether everyone's quality of life is likely to increase more with a curb or without one.

In the past, people have always been able to stave off a Malthusian catastrophe through increases in technological efficiency and breakthroughs in science. In the early 20th century, famines were averted by the advent of tractors. The most recent threat of catastrophe in India was averted by the introduction of high-yield varieties of wheat and rice and other grains, genetically engineered using hybrid techniques. It appears that a large portion of India wouldn't be alive today if it wasn't for genetic engineering.

To draw a parallel with IT, computers were big and unwieldy in the 1950s. They were horribly expensive, they were made of vacuum tubes and were very difficult to maintain. At that cost, some of the people who dealt with computers back then perceived that the world's total market was maybe for 5 or so computers.

Fifty-five years of technological advances later, OLPC are giving away laptops to children that cost $199 a piece. Silicon chips vastly superior to any computer in 1950 can be found in the cheapest cell phone.

Essentially, the optimists are saying that we are underutilizing our resources, and that there are magnitudes of improvement that can be made simply through advances in technology, i.e. by learning to use what we have more effectively. In this light, the more people we have, the more talented engineers we will have that will help to advance the world technologically. Hence, everyone's standard of living will improve even though the number of people is increasing.

Conversely, the pessimists are saying that the possibilities for major advance in some of the most crucial resources, say food or water, are limited. If this is so, then in fact increasing the population will lead to a Malthusian catastrophe, and the standard of living will drop considerably compared to keeping the population at current levels or reducing it.

Going with the optimists and allowing unchecked growth means risking a Malthusian catastrophe in the event that the expected and necessary breakthroughs don't materialize, and the world ends up short in one or more crucial resources.

On the other hand, curbing population growth when this is not necessary deprives the world of people who would otherwise contribute many new discoveries, creativity and technological advancement.

It all depends on whether we do or do not have vast unrealized efficiency reserves in our most crucial resources.