
Raymond Claude Ferdinand Aron was a French philosopher, sociologist, political scientist, and journalist.

Joxe Azurmendi Otaegi is a Basque writer, philosopher, essayist and poet. He has published numerous articles and books on ethics, politics, the philosophy of language, technique, Basque literature and philosophy in general.

Sir Isaiah Berlin was a Latvian-born British social and political theorist, philosopher and historian of ideas. Although he became increasingly averse to writing for publication, his improvised lectures and talks were sometimes recorded and transcribed, and many of his spoken words were converted into published essays and books, both by himself and by others, especially his principal editor from 1974, Henry Hardy.

Ward LeRoy Churchill is an American author and political activist. He was a professor of ethnic studies at the University of Colorado Boulder from 1990 until 2007. The primary focus of his work is on the historical treatment of political dissenters and Native Americans by the United States government. His work features controversial and provocative views, written in a direct, often confrontational style.

Gilles Deleuze was a French philosopher who, from the early 1950s until his death in 1995, wrote on philosophy, literature, film, and fine art. His most popular works were the two volumes of Capitalism and Schizophrenia: Anti-Oedipus (1972) and A Thousand Plateaus (1980), both co-written with psychoanalyst Félix Guattari. His metaphysical treatise Difference and Repetition (1968) is considered by many scholars to be his magnum opus. An important part of Deleuze's oeuvre is devoted to the reading of other philosophers: the Stoics, Leibniz, Hume, Kant, Nietzsche, and Bergson, with particular influence derived from Spinoza. A. W. Moore, citing Bernard Williams's criteria for a great thinker, ranks Deleuze among the "greatest philosophers". Although he once characterized himself as a "pure metaphysician", his work has influenced a variety of disciplines across the humanities, including philosophy, art, and literary theory, as well as movements such as post-structuralism and postmodernism.

George Friedman is a Hungarian-born U.S. geopolitical forecaster, and strategist on international affairs. He is the founder and chairman of Geopolitical Futures, an online publication that analyzes and forecasts the course of global events. Prior to founding Geopolitical Futures, he was chairman of its predecessor Stratfor, the private intelligence publishing and consulting firm he founded in 1996.

Martin Evan Jay is the Sidney Hellman Ehrman Professor of History Emeritus at the University of California, Berkeley. He is an intellectual historian whose research interests have connected history with other academic and intellectual activities, such as the critical theory of the Frankfurt School, social theory, cultural criticism, and historiography. He was elected a Member of the American Philosophical Society in 2019.

Milan Kangrga was a Croatian and Yugoslav philosopher who was one of the leading thinkers in the Praxis School of thought which originated in the 1960s in the Socialist Federal Republic of Yugoslavia.

Leszek Kołakowski was a Polish philosopher and historian of ideas.

Mihailo Marković, PhD was a Serbian philosopher who gained prominence in the 1960s and 1970s as a proponent of the Praxis School, a Marxist humanist movement that originated in Yugoslavia.

David McLellan is an English scholar of Karl Marx and Marxism. He was educated at Merchant Taylors' School and St. John's College, Oxford University.

José Guilherme Merquior was a Brazilian diplomat, academic, writer, literary critic and philosopher.

Antonio "Toni" Negri is an Italian Spinozistic-Marxist sociologist and political philosopher, best known for his co-authorship of Empire and secondarily for his work on Spinoza.

John B. Ridpath is a Canadian intellectual historian. He is an Objectivist and a retired associate professor of economics and intellectual history at York University in Toronto. He also taught courses at Duke University.

Thomas Sowell is an American economist, social theorist, and senior fellow at Stanford University's Hoover Institution.

Ferdinand Tönnies was a German sociologist, economist and philosopher. He was a major contributor to sociological theory and field studies, best known for his distinction between two types of social groups, Gemeinschaft and Gesellschaft. He co-founded the German Society for Sociology together with Max Weber and Georg Simmel and many other founders. He was president of the society from 1909 to 1934, after which he was ousted for having criticized the Nazis. Tönnies was considered the first German sociologist proper, published over 900 works and contributed to many areas of sociology and philosophy.