Fuente: Peter Kreef, Socrates meets Kant

p.24-25 KANT: Indeed. I was getting to that. I think we should distinguish two senses of the word. In the broad sense, I never ceased to be a Rationalist. But in the narrow sense, I was converted away from Rationalism by the arguments of David Hume. Let us take the broad sense first. Like most philosophers in my day, I was very much a part of the movement called the "Enlightenment", which saw science and the scientific method as a bright new hope for mankind to settle its old disputes and to progress into eras of not only scientific and technological progress but also human, humane, moral progress. We were animated by the hope that if we applied the more rigorously rational methods and the more open and unprejudiced attitudes of science to the problems of philosophy and morality and politics and even religion, we could overcome ancient superstitions, prejudices, and wars and significantly increase human happiness on this earth, perhaps even for ever, with no limit to this progress. This is the broad sense of "Rationalism".
The narrow sense is a particular answer to the primary question of epistemology. How do we find truth? Or, more specincaiiy, how do we find certainty? And Rationalism s answer is: by pure reason, not by sense experience.