The availability of labour influences wage rates and the larger the unemployed workforce grows, the more this forces down wage rates; conversely, if there are plenty jobs available and unemployment is low, this tends to raise the average level of wages—in that case workers are able to change jobs rapidly to get better pay. Marx discusses the army of labor and the reserve army in "Capital", Chapter 14, Counteracting Factors, Section IV. The army of labor getconsists in those working class people employed in average or better than average jobs. Not every one in the working class gets one of these jobs. There are then four other categories where members of the working class might find themselves: the stagnant pool, the floating reserves, the latent reserve and pauperdom. Finally, people may leave the army and the reserve army by turning to criminality, Marx refers to such people as lumpenproletariat. Marx then analyses the reserve army of labour in detail using data on Britain where he lived. Some economists such as Paul Samuelson have taken issue with Marx's concept of the reserve army of labour. Samuelson argues that much Marxian literature assumes that the "mere existence" of the unemployed drives down wages, when in reality is dependent upon contingent factors. (Are the unemployed easily available as replacements? Is the mere threat of replacement sufficient to get workers to accept a wage cut or does the employer have to demonstrate this is not an empty threat?) Samuelson argues that if prices also fall with money wage, then this does not mean real wages will fall. Samuelson also argues that wages will fall only until there are no more unemployed to bid it down: the reserve army can reduce wages only by decreasing its size. Samuelson's concludes that to mean that while the unemployed can reduce wages, they are incapable of reducing them to anywhere near subsistence levels before the unemployed all become employed. A similar argument was made by Murray Rothbard, who argued that if the reserve army lower wages by being absorbed into the ranks of the employed, then eventually it will disappear and be incapable of being a threat (that also means that the risk of perpetual impoverishment is averted). Rothbard observes that this is supported by modern market economics, which holds that unemployment lowers wages and thus ultimately eliminates itself. Thus, Rothbard concludes that the reserve army would ultimately cease to be a threat. Rothbard also argues that industries can experience an increase in demand for other works thanks to increasing productivity caused by technology, which will then decrease unemployment due to a greater demand for workers caused by expanding production capability.