Bertrand Arthur William Russell, 3rd Earl Russell was a British philosopher, logician, mathematician, historian, social reformer, and pacifist. Although he spent the majority of his life in England, he was born in Wales, where he also died. Russell led the British "revolt against Idealism" in the early twentieth century and is one of the founders of analytic philosophy along with his protégé Wittgenstein and his elder Frege. He co-authored, with A. N. Whitehead, Principia Mathematica, an attempt to ground mathematics on logic. His philosophical essay "On Denoting" has been considered a "paradigm of philosophy." Both works have had a considerable influence on logic, mathematics, set theory, linguistics and analytic philosophy. He was a prominent anti-war activist, championing free trade between nations and anti-imperialism. Russell was imprisoned for his pacifist activism during World War I, campaigned against Adolf Hitler, for nuclear disarmament. He criticized Soviet totalitarianism and the United States of America's involvement in the Vietnam War. In 1950, Russell was awarded the Nobel Prize in Literature, "in recognition of his varied and significant writings in which he champions humanitarian ideals and freedom of thought."

Alfred North Whitehead, OM FRS (15 February 1861-30 December 1947) was a philosopher and mathematician. He is the founding father of the philosophical school of process philosophy. This school has found many areas of application to the disciplines of ecology, theology, education, physics, biology, economics, and psychology. His early work was in logic, and physics. The three-volume Principia Mathematica (1910-13), written with Bertrand Russell is considered to be one of the most important classical works in mathematical logic. Starting late in 1910 Whitehead developed an interest in philosophy of science, and metaphysics. Whitehead's main point of departure from western philosophy is that reality was fundamentally constructed by events rather than substances which means that both are intertwined in a web of reality. Whitehead argued that "there is urgency in coming to see the world as a web of interrelated processes of which we are integral parts, so that all of our choices and actions have consequences for the world around us."

Maimonides (Moses ben Maimon 1138-1204) was born in Cordoba, Spain, but spent his most formative and productive years in Cairo, where he developed an enviable medical practice. He was appointed as the court physician to the Grand Vizier Al Qadi al Fadil, and thereafter to the Sultan Saladin. He continued to serve as the royal physician to the Sultan Saladin's son. In addition to being an admirable physician, he was also an important philosopher. Through the environment provided by Arabic culture he had access to classical Greek philosophy and medical writings.