Necessary Illusions: Thought Control in Democratic Societies is a 1989 book by US academic Noam Chomsky concerning political power using propaganda to distort and distract from major issues to maintain confusion and complicity, preventing real democracy from becoming effective. Like many of the titles by Chomsky, such as Pirates and Emperors the themes come from such titles as St. Augustine's City of God and Public Opinion by Walter Lippmann, the title of this book borrows a phrase from an earlier political commentary; in this case, Chomsky quotes from the writings of Reinhold Niebuhr.
Nearly the entire first half of the book is based on Chomsky's five 1988 Massey Lectures on Canadian Broadcasting Corporation Radio from November 1988 and extends his propaganda model to a variety of new situations. The remaining appendices address criticisms of the work and provide additional detail.
As a genre of political thought, parallels exist between Niebuhr's "necessary illusions" and the "noble lies" of Leo Strauss, "public relations" of Edward Bernays and "myth making" of Niccolò Machiavelli. Likewise, Chomsky's analyses in Necessary Illusions represent a refocus on the use of these patterns of power, which he implies to underscore the failure of populations - particularly in a representative democracy - to learn from history in this regard.