 Because the luck egalitarian proposals have a similar motivation to the Difference Principle the moral criticisms of them tend to be variations on those leveled against the Difference Principle. However, as noted above, what is practically required of a society operating under the Difference Principle is relatively straightforward. How the theoretical concerns of luck egalitarians are to be practically implemented is often not so clear. For instance, it has seemed impossible to measure differences in people’s natural  talents—unfortunately, people’s talents do not neatly divide into the natural and those for which people can be held responsible. A system of special assistance to the physically and mentally disabled and to the ill would be a partial implementation of the compensation system, but most natural inequalities would be left untouched by such assistance while the theories commonly require compensation for such inequalities. Exploring how in practical ways the economic systems can be refined to track responsibility while mitigating certain types of pure luck will be an ongoing challenge for luck egalitarians.