In epistemology and in its modern sense, rationalism is "any view appealing to reason as a source of knowledge or justification". In more technical terms, it is a method or a theory "in which the criterion of the truth is not sensory but intellectual and deductive". Different degrees of emphasis on this method or theory lead to a range of rationalist standpoints, from the moderate position "that reason has precedence over other ways of acquiring knowledge" to the more extreme position that reason is "the unique path to knowledge". Given a pre-modern understanding of reason, rationalism is identical to philosophy, the Socratic life of inquiry, or the zetetic (skeptical) clear interpretation of authority (open to the underlying or essential cause of things as they appear to our sense of certainty). In recent decades, Leo Strauss sought to revive "Classical Political Rationalism" as a discipline that understands the task of reasoning, not as foundational, but as maieutic. Rationalism should not be confused with rationality, nor with rationalization.

In politics, rationalism since the Enlightenment historically emphasized a "politics of reason" centered upon rational choice, utilitarianism, secularism, and irreligion — the antitheistic tendencies of this last aspect since having been partly ameliorated by millennials' more tolerant and utilitarian adoption of methodological, pluralistic rationalist practices applicable irrespective of religious or political affiliation.

Read more about Rationalism:  Background, Philosophical Usage