There are two routes available to the political economist in making a case for one system of social organization over another. There is the hard case, and the easy case. The easy case consists of assuming the ideal conditions that make the theorist’s system work. The hard case, on the other hand, consists is postulating less-than-idealized conditions for the system at hand and determining to what extent the system retains its desirable attributes. The hard case is hard because in order to demonstrate the desirability of a particular system under worse-case scenarios, the system must be robust. Robust systems, then, are precisely those that are able to stand up to the test of the hard case. In the face of less than ideal conditions, the system performs well nonetheless. Many systems can stand up to the test of the easy case, but very few remain standing when confronted with the hard case. The argument for liberalism made by its ‘founding fathers’ in the 18th century aimed to pass the test of the hard case.