When reviewing one of Hayek's books recently I became conscious of his willingness to make a number of important empirical judgments, particularly on trade unions, without accompanying them by any supporting evidence.² As an example, just one among many, consider his remarkable claim (in "1980s Unemployment and the Unions' — Hayek, 1991) that the legalised powers acquired by British trade unions prior to 1980 became "the biggest obstacle to raising the living standards of the working class as a whole ... the chief cause of the unnecessarily big differences between the best- and worst-paid workers ... the prime source of unemployment... [and] ... the main reason for the decline of the British economy in general" (Hayek, 1991, p. 344).