Rationalism, also known as the rationalist movement, is a philosophical doctrine that asserts that the truth can best be discovered by reason and factual analysis, rather than faith, dogma or religious teaching. Rationalism has some similarities in ideology and intent to humanism, secular humanism, and atheism, in that it aims to provide a framework for social and philosophical discourse outside of religious or supernatural beliefs; however, rationalism differs from both of these, in that:As its name suggests, humanism is centered on the dignity and worth of people. While rationalism is a key component of humanism, there is also a strong ethical component in humanism that rationalism does not require. As a result, being a rationalist does not necessarily mean being a humanist.
Atheism, a disbelief or lack of belief in God, can be on any basis, or none at all, so it doesn't require rationalism. Furthermore, rationalism does not, in itself, affirm or deny atheism, although it does reject any belief based on faith alone. Historically, many rationalists were not atheists. Presumably, people who are rationalists today generally do not believe that theism can be rationally justified, because modern-day rationalism is strongly correlated with atheism.
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