Rationalism is the philosophical theory that knowledge can be obtained by human reason alone. Some enthusiastic but uninformed Buddhists have claimed that the Buddha was a rationalist and that Buddhism is ‘pure rationalism.’
While Buddhism does have strong rational elements, probably more than most religions, it is an exaggeration to say that it is completely rational. The Buddha was too aware of the subtle influence that desire and prejudice can have on the thought processes to rely entirely on reason. According to him, three things have a role to play in the attainment of knowledge or wisdom - data obtained through education (sutamaya pannà), data obtained through reasoning (cintàmaya pannà) and data obtained by meditation (bhàvanàmaya pannà).