The doctrine that reason is the right basis for regulating conduct WordNet 3.0 & Open English WordNet

Freethought is an epistemological viewpoint which holds that beliefs should not be formed on the basis of authority, tradition, revelation, or dogma, and should instead be reached by other methods such as logic, reason, and empirical observation. Wikipedia

A position that beliefs should be formed only on the basis of logic, reason, and empiricism Wikipedia Disambiguation

A philosophical approach that argues that human behavior can be best understood by the application of reason, logic, and common sense. OmegaWiki

A view that the fundamental method for problem solving is through reason and experience rather than faith, inspiration, revelation, intuition or authority. Wiktionary