Axel Gosseries wrote: >I was wondering what the main reason would be why Sidgwick did not see >that improvements to climate could actually be sold (through a tradable >quotas scheme). Any suggestions? Axel: who would buy such improvements in the absence of government requirements that the climate be undegraded? Tradable quotas today occur in the context of restrictions on emissions put in place by governments and enforced. Without such restrictions, the benefits are not appropriable - just as Sidgwick says. A better climate is a public good which is subject to free-riding. If one of us gets it, all of us do - it is impossible to exclude non-payers. Each of us does better not paying for it no matter what the others do, so no one pays and the entrepreneur attempting to sell the improvement fails. Kevin Quinn