Some scholars argue that superstardom plays a useful role in society. Caillois cites Rawls, who states that the "premiums earned by scarce natural talents serve to cover the costs of training and to encourage the efforts of learning, as well as to direct ability to where it best furthers the common interest". Cowen cites Rosen to argue that "the superstar effect is welfare-improving (consumers get better performances) even if it leads to raising income inequality" and adds that the "superstar phenomenon should not be overstressed [...] indeed, fame is a positive-sum game, not a negative nor a zero-sum one". Cowen states that "countervailing forces operate, such as a convergence of quality that limits the ability of the very best stars to dominate the market for long, or more radically the elastic supply of fame". This means that "when demand for fame increases, the numbers of prizes, rewards and whatever fame generating distinctions is rising too".