Rationalism is absolutely indispensable when seeking a Science Victory, and is also quite helpful for Domination Victory seekers who want to field cutting-edge military units. Be aware that in Rise and Fall and Gathering Storm, only cities with both a Population of 10 or more and an adjacency bonus of +3 or more for their Campuses will fully enjoy the policy's Science bonus.
Civilopedia entry Edit
Rationalism is the worldview that looks to reason (rather than, say, blind faith or magic mushrooms) to explain the world. In this philosophy, reason trumps all other ways of knowing things, including any data gathered by one's five senses. Its roots can be traced back to the great Socrates, but it enjoyed something of a resurgence following Christian repression during the 16th and 17th centuries during the Scientific Revolution. Scientist-philosophers such as Réne Descartes, labelled the “father of modern philosophy,” Spinoza, Leibniz, and Kant altered the way humans viewed their world in profound ways and made rationalism the new faith.