The "marketplace of ideas" was first cultivated by John Stuart Mill and applies to a key part of the ideals that led to the "Enlightenment" in the 17th century and the 18th century, during libertarian theory. The concept of a “marketplace of ideas” is based on the belief that “truth” emerges from the competition of ideas, in a free and transparent public forum. The “marketplace of ideas” is a justification for free speech and expression, with the idea that free speech must be allowed because it will lead us to the truth. John Stuart Mill's book "On Liberty" justifies the freedom of the individual as opposed to total authoritarian control. In the introduction to “On Liberty,” Mill lists the three main fundamental freedoms in order of importance, placing the following as the most important: Freedom of thought and emotion. This includes the freedom to act on such thinking, that is, freedom of expression. Mill's idea, in correlation with the ideas adopted by other prominent figures (Milton, Locke, Paine and Jefferson) of this historical period, led to revolutions, which gave rise to the libertarian era. This new era was based on new philosophies in which man was seen as rational and capable of thinking for himself. The press has become the ally of people in search of truth, the press has also become a “watchdog” in holding systems of government to account. The “marketplace of ideas” would become an important part of journalism and is still present and in force today. You could say that the “marketplace of ideas” has gone crazy. As technology advances, we witness the ever-changing adaptation of journalism and its techniques. The educated journalist or the rich publisher are no longer the only ones to denounce our medium and Assange's “Wikileaks”. John Stuart Mill was not alone in believing that free speech would lead to the truth. According to Wikipedia, John Milton suggested that restricting free speech was unnecessary because "in a free and open encounter" the truth would prevail, and U.S. President Thomas Jefferson argued that it is prudent to tolerate " error of opinion… where reason is free to fight.” "We also see Fredrick Siebert assert in "Four Theories of the Press" the idea of ​​freedom of expression as being "self-correcting." It is safe to say that we are in our position to date. more democratic in terms of journalism and access to information in the Western world, but the future of the press remains unknown. We can only hope that the “market of ideas” continues to be useful to our growth and. to our development, and does not prove fatal to our press and its future..