permits ”. the state decides the total amount of emissions tolerated and provides for an initial distribution of the relative quotas ; private firms can then trade them against payment. those who are able to reduce emissions at low cost will take advantage of the chance to sell their shares to firms for which a reduction is more expensive. the overall reduction will not change, but the cost of achieving it will fall. this shows that the fourth solution, i. e. relying to a certain extent on the market, is not actually entirely excluded, even in the case of public goods. ronald coase, another nobel prize winner for economics, went so far as to argue that, in the absence of transaction costs and provided that property rights are clearly defined, there is no good to which the market cannot assign an efficient price. his paper on lighthouses is famous ( that is why wikipedia mentions them ), in which he tries to demonstrate that for a certain period in england, the coastal lighthouse service, apparently the most public of public goods, was actually supplied by private companies for profit. it should be pointed out that the details of this story are not uncontroversial. above all, however, the absence of transaction costs required for the validity of coase ’ s ” theorem ” is a very demanding condition. put simply, it assumes that it is possible to stipulate a private agreement instantly and at no cost, according to which all the stakeholders ( potentially millions or billions of people ) voluntarily “ buy ” ( for example ) the polluter ’ s renunciation of the right to pollute. difficult? impossible? in a literal sense, yes, of course. let us consider, though, another element of the ongoing debate on global warming. as we know, the emerging countries complain because the advanced countries want to impose strict limits on their emissions, having themselves pumped countless megatonnes of co2 into the atmosphere from the beginning of the industrial revolution until today. 25 the emerging economies say that they are only willing to adopt certain standards in exchange for cash transfers from the rich countries that are insisting on imposing them. in fact, the paris agreements already included this sort of idea and the most recent negotiations have further advanced the debate. think about it : if we look closely, this is basically the application of a version of coase ’ s theory, in which a few dozen governments try to negotiate on behalf of billions of people. anyone interested in a simple quantitative summary in graphic form can consult hannah ritchie,

##ita le vostre tempie! “ ah, deluded souls, wicked creatures who twist your hearts away from such a good, directing your faces toward emptiness! ” even before this, in canto xi of the purgatorio, that of the prideful, oderisi da gubbio had warned about fame ( 100 - 102 ) : non e il mondan romore altro ch ’ un fiato di vento, ch ’ or vien quinci e or vien quindi, e muta nome perche muta lato. “ the clamor of the world is nothing but a breath of wind that comes now from here and now from there, and changes names because it changes directions. ” yet on fame, as on many other things, dante ’ s thoughts were not easily reconcilable ( inferno iv, 76 - 78 ) xvi ( 66 ) xxiv, 46 - 51 ; and there may be more passages to consider ). that in the commedia one finds everything and the opposite of everything is part of its centuries - long appeal. lines 73 - 75. each one ’ s portion ). in 1954, paul samuelson ( who would later win the nobel prize for economics ) formalised the concept of rival goods. 22 a good is defined as “ rivalrous ” if its enjoyment by one party is diminished when another party consumes the same good. we are in the classic chicken - sharing situation, and the consideration is precisely that which dante has virgil utter. samuelson, however, unlike dante, also identified a category of ( worldly ) goods that are “ non - rivalrous ”. for example, national defence or street lighting. if i benefit from a street lit at night, i do so without preventing my fellow citizens from enjoying the same good. these are non - rivalrous economic, worldly goods. if the two could meet, samuelson would tell dante that there are not only spiritual goods outside the sphere of envy. on the other hand, it is interesting how dante, in warning his contemporaries against this capital sin, highlighted a characteristic of worldly goods, or rather of many of them, which is their rivalrous nature – something which would only be formalized many centuries later by economists. although commentators have identified the probable origin of dante ’ s thinking ( saint augustine plays on the same theme in the city of god ), 23 nobody, that i know of, has emphasised the