Tocqueville and Liebling notwithstanding, freedom of the press in democratic societies is a nearly unchallengeable dogma – essential, it is thought, to individual autonomy and self-expression, and an indispensable element in democracy and the attainment of truth. Both its eloquent theoreticians and its contemporary popular advocates defend freedom of speech and freedom of the press in the same stroke, with the implication that they are inseparable, probably equivalent, and equally fundamental.

At the same time, we know that the press in its most characteristic modern incarnation – mass media in mass society – works not only to enhance the flow of ideas and information but also to inhibit it. Nothing guarantees that all valuable information, ideas, theories, explanations, proposals, and points of view will find expression in the public forum. Indeed, many factors lead us to expect that they will not. The most obvious is that “mass media space-time” is a scarce commodity: Only so much news, analysis, and editorial opinion can be aired in the major channels of mass communication.

Which views get covered, and in what way, depends mainly on the economic and political structure and context of press institutions, and on the characteristics of the media themselves.