We have seen, over the last three decades, an immense spread of economic thinking in all branches of social science (see, e.g. Hartley, 1992); a phenomenon commonly referred to as ‘economic imperialism’ (Tullock, 1972; Brenner, 1980; Stigler, 1984; Radnitzky and Bernholz, 1987; Udehn, 1992), or ‘universal economies’ (Radnitzky, 1992). Outside its traditional domain, the economic approach has proved most useful in the analysis of politics. Since the 1950s, there has been an invasion of economists into political territory. Many political scientists, too, have become impressed by the apparent power of this perspective and adopted its tools. Being a discipline with a topic, but no particular approach, political science is easily subjected to the influence of neighbouring disciplines (cf. Truman, 1955; Greer, 1969:55; Riker, 1982a:4).1