In the argument of empiricism versus rationalism, empiricism is the superior position. Rene Descartes supports rationalism, which is the attainment of knowledge through reason. David Hume supports empiricism, the attainment of knowledge a posteriori, through experience. Both positions have strong arguments. Descartes is wary of "[accepting] anything as true that [he] did not plainly know to be such" . Descartes believes that we must "be assured of using [our] reason in everything..." in order to gain true knowledge. Hume, on the other hand, believes that the association of ideas is what gives us our knowledge. He uses the "three principles of connexion among ideas, namely, resemblance, contiguity in time or place, and cause or effect" to describe this method of empiricism. Hume believes we connect these ideas within our own minds with previous ideas we have had through experience.
The explanation for why empiricism is superior to rationalism can be found in the thought that empiricism is certain, whereas rationalism is probable.
Rationalism is faulted in the fact it is not a unified position. Some rationalists believe that some truths about reality can be acquired through reason alone, while others, such as Descartes, believe that all truths are obtained through reason. This is made clear when Descartes states, "I have always taken never to accept into my beliefs any new opinions for which I did not have very certain demonstrations..." "Demonstration" is another word for experience. Empiricism seems to be a more solid position in that all empiricists agree that knowledge requires experience; "custom...is that principle alone, which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those that have appeared in the past".