Adam Smith was a Scottish economist and philosopher who was a pioneer in the field of political economy and key figure during the Scottish Enlightenment.

French aristocrat and political thinker Alexis Charles Henri de Tocqueville transformed how the world understood democracy through his keen observations of 19th-century America.

William James Durant was an American historian and philosopher, best known for his eleven-volume work, The Story of Civilization, which contains and details the history of Eastern and Western civilizations.

Bertrand Arthur William Russell (1872–1970) was a British philosopher, logician, and writer, born on 18 May 1872 at Trelleck. A founding figure of analytic philosophy and logicism, he published extensively on logic, epistemology, and the theory of knowledge, with his best-known works including Principia Mathematica and A History of Western Philosophy (1945), which became a bestseller. He received the 1950 Nobel Prize for Literature.

Friedrich Wilhelm Nietzsche was a German philosopher and writer who started his career as a classical philologist and turned to philosophy early in his academic career.

Massimo Pigliucci is a professor at The City College of New York who has published 194 technical papers in science and philosophy and is the author or editor of 23 books. He is best known for the bestselling How to Be a Stoic: Using Ancient Philosophy to Live a Modern Life (Basic Books). He holds a PhD in evolutionary biology and has also worked as a producer, director, and writer.