1. 1 Wage Setting vs. Wage Taking Inhisground-breakingmonographMonopsonyin Motion:Imperfect Competitionin Labor Markets, Manning (2003a, p. 3) starts his argument in favour of a monop- nistic approach to labour market phenomena with a compelling case against perfect competition: 'What happens if an employer cuts the wage it pays its workers by one cent? Much of labor economics is built on the assumption that all existing workers immediately leave the rm as that is the implication of the assumption of perfect competition in the labor market. ' Taking the model literally, this would indeed be its prediction. Other than in a perfectly competitive labour market where employers are wage takers unable to deviate from the market wage, a monopsonistic approach assumes that employers possess signi cant wage-setting power and actually ex- cise their market power. Put differently, it argues that some of the workers stay with the rm, giving the rm some discretionin wage setting. Technically speaking, the main difference between the two models is that under perfect competition the laboursupply faced by the rm is in nitely elastic, whereas this doesnot hold under 1 monopsony. While Manningis right in stating that the modelof a perfectlycompetitivelabour market still dominates teaching and considerable parts of labour economics, there are of course notable exceptions, for instance, the ef ciency wage (e. g. , Schlicht, 1978; Salop, 1979a; Shapiro and Stiglitz, 1984; Yellen, 1984), the search and eq- librium unemployment (e. g.