Murray is the man behind the underclass - the notion that there is a group of unskilled, unemployable, unmarriageable, welfare-junkie, crime- prone, drug-taking amoral proles who are somehow different from "the rest of us". This is the thinking that has provided a cloak of respectability for attacks on single mothers, plans to introduce draconian cuts in welfare benefits and even for the idea that illegitimacy should be restigmatised.
Most recently he has revived the old notion that there is a link between race and IQ - arguing that the supposed lower intelligence of blacks is playing an important role in exacerbating social inequality in the United States.
Murray first outlined his fears of a growing underclass in 1984 in Losing Ground: American Social Policy 1950-1980. His theory was simple. Previously it had generally been assumed that crime was linked in some way to unemployment. Murray plotted graphs of the two sets of statistics and pronounced that they bore little relation to each other. Crime had begun to rise steeply in the 1960s when unemployment was low and society was affluent. Yet if the crime rate was plotted against the rate of illegitimate births the two graphs were exactly the same.
Murray assumed a causal connection on the grounds that in the past a single woman with a small child has never been a viable economic unit. Social security payments have changed all that. Such women now have no need to forge permanent alliances with the young unskilled males who are by nature "essentially barbarians'' until they are civilised by marriage. The men turn to drugs and crime and a vicious circle is created. This is the underclass - a group defined not by poverty but by its anti-social behaviour.
But even some of his supporters have been embarrassed by his latest effort, The Bell Curve: Intelligence and Class Structure in American Life. It insists that intelligence is unevenly distributed by ethnic group in the American population. On average, blacks are 15 points below whites, while "East Asians'' are 10 to 15 points higher.