Marketplace of ideas

The "marketplace of ideas" is a rationale for freedom of expression based on an analogy to the economic concept of a free market. The "marketplace of ideas" holds that the truth will emerge from the competition of ideas in free, transparent public discourse. The "marketplace of ideas" concludes that ideas and ideologies will be culled according to their superiority or inferiority and widespread acceptance among the population. This concept is often applied to discussions of patent law as well as freedom of the press and the responsibilities of the media in a liberal democracy.

The marketplace of ideas metaphor is founded in the philosophy of John Milton in his work "Areopagitica" in 1644 and also John Stuart Mill in his book, On Liberty in 1859 (although neither use the term "marketplace"). It was later used in opinions by the Supreme Court of the United States. The first reference to the "free trade in ideas" within "the competition of the market" appears in Justice Oliver Wendell Holmes, Jr.'s dissent in Abrams v. United States. The phrase "marketplace of ideas" first appears in a concurring opinion by Justice William O. Douglas in the Supreme Court decision United States v. Rumely in 1953: "Like the publishers of newspapers, magazines, or books, this publisher bids for the minds of men in the market place of ideas." The Court's 1969 decision in Brandenburg v. Ohio enshrined the marketplace of ideas as the dominant public policy in American free speech law (that is, against which narrow exceptions to freedom of speech must be justified by specific countervailing public policies). It has not been seriously questioned since in U.S. jurisprudence.

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