Rationalism is a classic philosophy essay by John Mackinnon Robertson. The names 'rationalist' and 'rationalism' have been used in so many senses within the past three hundred years that they cannot be said to stand quite definitely for any type or school of philosophic thought. For Bacon, a 'rationalist' or rationalis was a physician with a priori views of disease and bodily function; and the Aristotelian humanists of the Helmstadt school were named rationalistas about the same period by their opponents.