“While we repudiated with the greatest energy that tyranny of society over the individual which most Socialistic systems are supposed to involve, we yet looked forward to a time when society will no longer be divided into the idle and the industrious; when the rule that they who do not work shall not eat, will be applied not to paupers only, but impartially to all; when the division of the produce of labour, instead of depending, as in so great a degree it now does, on the accident of birth, will be made by concert on an acknowledged principle of justice; and when it will no longer either be, or be thought to be, impossible for human beings to exert themselves strenuously in procuring benefits which are not to be exclusively their own, but to be shared with the society they belong to. The social problem of the future we considered to be, how to unite the greatest individual liberty of action, with a common ownership in the raw material of the globe, and an equal participation of all in the benefits of combined labour. We had not the presumption to suppose that we could already foresee, by what precise form of institutions these objects could most effectually be attained, or at how near or how distant a period they would become practicable. We saw clearly that to render any such social transformation either possible or desirable, an equivalent change of character must take place both in the uncultivated herd who now compose the labouring masses, and in the immense majority of their employers. Both these classes must learn by practice to labour and combine for generous, or at all events for public and social purposes, and not, as hitherto, solely for narrowly interested ones. But the capacity to do this has always existed in mankind, and is not, nor is ever likely to be, extinct. Education, habit, and the cultivation of the sentiments, will make a common man dig or weave for his country, as readily as fight for his country. True enough, it is only by slow degrees, and a system of culture prolonged through successive generations, that men in general can be brought up to this point. But the hindrance is not in the essential constitution of human nature. Interest in the common good is at present so weak a motive in the generality not because it can never be otherwise, but because the mind is not accustomed to dwell on it as it dwells from morning till night on things which tend only to personal advantage. When called into activity, as only self-interest now is, by the daily course of life, and spurred from behind by the love of distinction and the fear of shame, it is capable of producing, even in common men, the most strenuous exertions as well as the most heroic sacrifices. The deep-rooted selfishness which forms the general character of the existing state of society, is so deeply rooted, only because the whole course of existing institutions tends to foster it; and modern institutions in some respects more than ancient, since the occasions on which the individual is called on to do anything for the public without receiving its pay, are far less frequent in modern life, than the smaller commonwealths of antiquity. These considerations did not make us overlook the folly of premature attempts to dispense with the inducements of private interest in social affairs, while no substitute for them has been or can be provided: but we regarded all existing institutions and social arrangements as being (in a phrase I once heard from Austin) ‘merely provisional,’ and we welcomed with the greatest pleasure and interest all socialistic experiments by select individuals (such as the Co-operative Societies), which, whether they succeeded or failed, could not but operate as a most useful education of those who took part in them, by cultivating their capacity of acting upon motives pointing directly to the general good, or making them aware of the defects which render them and others incapable of doing so.”
—From John Stuart Mill’s Autobiography (1873). Part of this passage was quoted at the end of G.A. Cohen’s chapter on “The Incentives Argument,” in his book, Rescuing Justice and Equality (Harvard University Press, 2008). I was reading afresh the section on the “lax” and “strict” interpretations of Rawls’s “difference principle,” which has to do with the incentives of market-maximizing “high fliers” (like doctors in the U.S., say, in contrast with Cuban doctors, a salient comparison highlighted by the fact that Cuba provides ‘more medical personnel to the developing world than all the G8 countries combined’). As Cohen writes in the conclusion to his chapter, “Rawls’s lax application of his difference principle [which is nonetheless justified in some policy contexts] means ‘giving to those who have.’ He presents the incentive policy as a feature of the just society, whereas it is in fact, and as Mill says, just ‘highly expedient’ in society as we know it, a sober ‘compromise with the selfish type of character’ formed by capitalism. Philosophers in search of justice should not be content with an expedient compromise. To call expediency justice goes against the regeneration to which Mill looked forward at the end of this fine passage.” In other words: “high fliers would forgo incentives properly so-called in a full compliance society governed by the difference principle [i.e., on a strict reading thereof] and characterized by fraternity and universal dignity.”
 In one of its formulations, the principle states “that inequalities are just if and only if they are necessary to make the worst off people in society better than they would otherwise be.” Cohen “disagree[s] sharply with Rawls on the matter of which inequalities pass the test for justifying inequality it sets and, therefore, about how much inequality passes the test.” The kernel of Cohen’s critique of Rawls on this score is that he does not apply the difference principle “in censure of the self-seeking choices of high-flying marketeers, choices which induce an inequality that...is harmful to the badly off.” See, in addition to the more thorough treatment in Rescuing Justice and Inequality (2008), the (rhetorically) accessible analysis provided in Cohen’s Gifford Lectures (1996) and published in his book, If You’re an Egalitarian, How Come You’re So Rich (Harvard University Press, 2000): 117-133.
 See, for example, John M. Kirk and H. Michael Erisman, Cuban Medical Internationalism: Origins, Evolution, and Goals (Palgrave Macmillan, 2009), and Steve Brouwer, “The Cuban Revolutionary Doctor: The Ultimate Weapon of Solidarity,” Monthly Review, January 2009 (Vol. 60, No. 8).