Some Marxists call the factors that interfere with judgment “false consciousness.” They argue that false consciousness accounts for the failure of revolutionary ideology to attract adherents among the working class in the developed world. On this view, it wasn’t outright repression or censorship that prevented the workers from adopting a Marxist perspective. It is was the subtle and concealed influence of capital on their ability to exercise their capacity to make their own decisions.

These tensions in Mill’s defense of intellectual freedom were recognized in the 19th century. What we now call political correctness was first articulated in the 1960s by the brilliant German-born philosopher Herbert Marcuse. Marcuse’s achievement was to turn Mill’s argument for free discussion, at least in a modern Western society, against its explicit conclusion.

Marcuse undertakes this inversion, worthy of a black belt in dialectical reasoning, in the 1965 essay “Repressive Tolerance.” In it, Marcuse argues that the marketplace of ideas can’t function as Mill expected, because the game is rigged in favor of those who are already powerful. Some ideas enjoy underserved appeal due to tradition or the prestige of their advocates. And “consumers” are not really free to choose, given the influence of advertising and the pressures of social and economic need. Thus the outcome of formally free debate is actually predetermined. The ideas that win will generally be those that justify the existing order; those that lose will be those that challenge the structure.

This prong of the argument is close to the standard critique of false consciousness. But Marcuse links it to Mill’s distinction between those who are and are not capable of participating in and benefitting from the unrestricted exchange of ideas.

According to Marcuse, many people who appear to be rational, self-determining men and women are actually in a condition of ideological enforced immaturity. They are therefore incapable of exercising the kind of judgment that Mill’s argument presumes. In order to make debate meaningful, they need to be properly educated. This education is the responsibility of those who have already shown themselves to be capable of thinking for themselves—in this case, left-wing intellectuals rather than Victorian colonial administrators.

One might wonder how either Mill or Marcuse could be so sure that their kind of people knew what was best for others. The answer is that they regarded the truth as obvious.