While fertility is an important part of keeping a powerful, mobile and advancing workforce part of the economy, there simply may not be enough room for that model anymore. Malthus wrote his classic in the 19th century; well before modern innovations dashed his predictions for a crushing carrying capacity on earth: we haven't begun making Soylent Green either. Although technological innovation may push the carrying capacity of earth some more, its clear that current rates of population growth may be unsustainable within two or three generations. The idea espoused rings true to me; among the millions born every year, surely one Feynman, one Einstein, one George Bernard Shaw must be born among them. But the more frightening prospect isn't that great people will no longer be born, but that they are already born and are starving away. In finance jargon, instead of capital widening, perhaps we too should deepen our capital.

The American Dream is indeed a powerful motivator. The idea that a well educated public that is at the same time aware of their stature and their desires in society is a great start. However, while the market demands "highly educated, high IQ persons", the analogy extends to so called "market exposure": those who are above the median starting line to begin with usually start with much greater exposure tho those in key positions and other highly educated, high IQ persons. If Judge Posner's viewpoint truly is a bit Rawlsian in nature (and I may just be misinterpreting his remarks), than even a great, solid childhood education coupled with medical benefits and a shift in the tax code is not enough. Being blind to exposure requires a fundamental change in the way society perceives itself. What that change is exactly is up for debate.

Sir- The proposal of a Carbon Tax as suggested is in of itself not a bad idea. However, it is not enough. As you pointed out, it's Achilles' Heel is that the largest companies can simply exceed the limit and continue emitting carbons, albeit possibly at a lower rate because of a new equilibrium point in which it no longer becomes economically feasible to continue. Furthermore, depending on the way the tax system is set up, larger companies may simply budget in addition carbon costs to their suppliers, essentially driving up the price on almost everything while having a minimum impact on carbon emissions. Top down approaches, such as the carbon tax or some of its more exotic variants such as a tax on digging out carbon in the first place (see "Pay nations to keep carbon in the ground" by Bard Harstad in the Financial Times, July 4th) is that it assumes that people can be goaded merely by prices. Perhaps a more effective approach is to combine a Carbon Tax system with both more education, particularly amongst the youths, and a paradigm shift. Teaching youths about the science of climate change might hopefully create a grassroots desire for change in overall carbon policy, such as in Europe where a Carbon tax system, albeit defanged, is in place. It gives a double impetus for polluters to stop both from the top down and from the bottom up. Further, the carbon debate should not always be centered around the idea of global warming. While truly a noble cause, global warming is not immediate nor tangible enough to drive an impact without having the luxury of collecting data trends over a number of years. Rather, it can be phrased around other talking points ranging from health (ie smog and water pollution) to national security (the US is still dependent on many other countries for fuel). Carbon rights is coming to be one of the definitive issues of the 21st century. Yet, like carbons' effects, it is being fought slowly on a grand scale due to the sheer complexity and political difficulty it poses. Complexity can be overcome with passion; there are plenty of minds, young and old, already working to come up with alternatives to carbon based fuels. The political difficulty is different. Rather than rely on the courage of an outstanding Congress or waiting for another Churchill or F.D.R., we should seek to change the political arena to begin with.