Sustainability and the Value of Human Life
Now, the obvious answer is that 'human life is priceless', and though this is an admirable thought it fails a number of tests in the real world. Societies regularly make tradeoffs between economic efficiency and human lives: sure, reducing the concentration of pollutants in the air might save the one-in-one-hundred-thousand cancer deaths it causes, but the billions of dollars it costs to implement the necessary regulations simply isn't worth it.
Consider human beings as an economic resource. There's a certain supply of people (the population) and a certain demand for them (the unemployment rate in the economy.) Now, for most goods, if you hold demand constant, and increase supply, the value of the good decreases. Thus you'd expect that in a society whose population has increased enourmessly, you'd see the value of human life plunge.
Oddly this hasn't happened, at least in developed nations. Despite the population increasing by probably an order of magnitude over the past thousand years, the value of human life has increased still more. Back in the dark ages, life was cheap. Now it's more precious than ever.
I'd suggest the logical reason for this would be that demand hasn't remained constant; rather, it's growth has outstripped the growth in supply. As the economy increases in size and complexity, the contribution of each worker (more productive than his ancestors could ever have been) is more valuable, even though that worker consitutes a smaller overall percentage of the economy and the population.
I had an interesting discussion with a colleague today during which this came up. He brought up the sustainability question (you know, "Is all this economic growth really sustainable?") which immediately made another connection for me. The sustainability argument rests on the idea, more or less in the face of the evidence, that the productivity of a human being is more or less fixed. One more human in the population is just another mouth to feed, sucking up resources and producing little of value. If the premises of 'sustainability' were correct, then the economy wouldn't have grown at all in the past several hundred years and (assuming similar population growth) we'd all be much, more poorer than a Dark Ages peasant. The value of a human life would likely have declined over the same period, down to virtually nil.
Given that the opposite has happened, I think it's safe to assume that the sustainability argument is bunk.