Very often, skeptical people who do not believe in objective truth and only admit 'their truth' accept without batting an eyelid many plausible lies that reach them, especially through social networks. The pragmatism of our time puts the occasional usefulness of lies before the moral value of truth; moreover, it creates emotional and plausible lies that the general public is unable to detect and unmask.

To designate that subject of lies, the term post-truth is used, which the Dictionary of the Royal Spanish Academy defined in 2016 as "Deliberate distortion of a reality, which manipulates beliefs and emotions in order to influence public opinion and social attitudes".

This concept grew in popularity following the election of the current U.S. president, Donald Trump, and the Brexit campaign. Its origin, however, dates back to the early 1990s. In English, the term post-truth was first used in 1992 and was desifned as word of the year in 2016 by the Oxford dictionary.

Post-truth is one of the effects of the excessive use of immediacy and social networks to influence the public through the manipulation of communication and emotions.

If to postmodern individualism, which seeks to legitimize its individuality as the principle of all rule, we add a truth that loses consistency through saturation, we have as a logical result a truth that is based neither on rational principles nor on demonstrable facts, but a truth that appeals to subjectivity and emotions.

Post-truth is presented as an interpretable truth, another consumer product, whose raison d'être is not based on demonstrable facts, but on the emotions of each individual. Postmodern man is offered post-truth as an apparent truth to his liking; an individual truth chosen on the basis of feelings, and therefore irrational. The British philosopher A.C. Grayling, who campaigned against Brexit, is horrified by the possibility of a world dominated by post-truth: "It would be a corruption of intellectual integrity and a great damage to the whole fabric of democracy," he says. He adds that the world and politics changed after 2008, following the severe financial crisis: "With a groundswell of economic resentment unleashed, it is not difficult to 'hype' emotions on issues like immigration."

An example: the publication of a post-truth claiming that immigrants will seriously increase unemployment in a given country would be credible, thus giving rise to a social movement of xenophobia.

Among the main causes of Trump's triumph is his promoters' handling of post-truth. This means that the interpretation and understanding of objective facts are subordinated to the manipulation and molding of emotions and personal beliefs carried out by many leaders and social orienters. Truth is presented as something that is felt and is consistent with the beliefs and imaginaries of a social collective, not with what happens in reality.

There are many political parties that use post-truth as a communicational strategy integrated in the use of propaganda and strategic communication for manipulation and social control.

For Jairo Hernando Gómez Esteban, today we need a Education based on self-criticism, in which the satisfaction of immediate material needs is confronted with the School of imagining possible shared worlds; and in which reflexivity transcends the appearance and vulgarity of reality as it is revealed to our senses.