broken_keyboard said:
You ignore that cost because it is (literally) nothing. The future generations don't exist. One musn't go around abrogating the rights of real, living human beings to enjoy their lives and drive their SUVs in the name of ... nothing.
That's an interesting way of looking at it, but I think it has an inherent problem.
See, when you make an investment you understand that in the future you will be rewarded with more money than you initially put in. If you buy a stock, you believe the company will make more money and that this will cause the stock to rise, you sell the stock and make a nice profit. Simple, and entirely dependent on the notion of 'future value.' We do this every day with lots of things in the economy. We make decisions about future value, the notion of credit, the notion of even the value of currency based on gold, is entirely focused on future value. Car prices, houses, college education, are all based on judgments that proscribe a future value to each thing.
Your system assumes that investments are worthless because the future provides a zero-sum investment. But, this isn't true at all.
In fact, the entire idea of long-term construction (highways, pyramids) depend on the idea that the future will make this worthwhile. We built the Interstate Highway system not for the cars of the day, but the cars of today. We also built our nuclear arsenal not for Korea or Vietnam, but the future war we believed would happen as World War III.
See, the future has value because we're going to be there soon. So, we don't just build for future generations, but also for us. We assume that in 5, 10, 20 years we will still exist and therefore we want the same things around, or we hope for things to be better. You make the assumption that the future is invalid and I would argue that not only is the future valid, but that the future is more valid than the present and certainly more important than the past.
Furthermore, if we were able to stop using cars our air would become clearer, thus resulting in cleaner air for us and maybe a slowing of terrorismless money for the Sauds means less money for al-Qaedawhich means we could get a tax break, which means more money to spend on a new Macintosh. You see, the future comes quickly. Sooner than you think.