Intellectuals - and particularly academics - have been accused by one of their own of making the world a worse and more dangerous place in the 20th century.
Thomas Sowell, senior fellow of the Hoover Institution at Stanford University, claims that academics cling to their opinions even in the face of evidence to the contrary.
In a new book, Intellectuals and Society, Dr Sowell says intellectuals, whom he defines as the "producers of ideas", have probably never played a larger role in society.
Yet he says that unlike other professionals, they are rarely held to account.
The constraints on business leaders, doctors and athletes mean they face "high and often ruinous costs for persisting in ideas that turn out not to work", Dr Sowell explains.
"No such inescapable constraints confront people whose end products are ideas and whose ideas face only the validation of like-minded peers."
That is particularly true for academics who "control their own institutions and select their own colleagues and successors", he argues.
Professors are not fired because they vote for disastrous campus plans or advocate policies that turn out to be catastrophic for the world.
However, not everyone falls foul of Dr Sowell's damning analysis.
He excludes Chicago School of Economics professor Milton Friedman, as he was "atypical of the intellectuals of his time". Scientists such as Albert Einstein are also spared, as there is a "history of prevailing beliefs among scientists that they were forced to abandon in the face of contrary evidence".
Others are not so fortunate. Dr Sowell attacks philosopher Bertrand Russell for advocating British disarmament in the 1930s and accuses Karl Marx of a "fundamental misconception" - that labour is the real source of wealth.
As a more recent example of an "unaccountable academic", he cites Paul Ehrlich, professor of biology at Stanford University, who in 1967 predicted worldwide famine.
Dr Sowell says that despite his incorrect prediction that "hundreds of millions of people will starve to death" in the 1970s and 1980s, Professor Ehrlich retains popular acclaim.
Intellectuals and Society accuses academics such as Professor Ehrlich of having a "huge investment of ego" in a particular set of social or political opinions, and of pursuing a vision of a world in which intellectuals are exalted and form "a self-anointed vanguard".
The concept of academic freedom enshrines intellectuals' lack of accountability to the world, Dr Sowell adds: "From unaccountability to irresponsibility can be a very short step."
Asked what principles he would put in place to govern academics' contributions to public debate, he said: "This is not a book about proposing reforms. It is a book that seeks to understand the general patterns found among contemporary members of the intelligentsia, as well as what they've said and its impact on the societies in which they said it."
That impact has been to "narrow the scope of the freedoms enjoyed by ordinary people to run their own lives, much less to shape government policy", he concludes.