by theologians and drawing upon Plato, Aristotle, and early Church writings. Descartes argued that many predominant Scholastic metaphysical doctrines were meaningless or false. In short, he proposed to begin philosophy from scratch. In his most important work, Meditations on First Philosophy, he attempts just this, over six brief essays. He tries to set aside as much as he possibly can of all his beliefs, to determine what if anything he knows for certain. He finds that he can doubt nearly everything: the reality of physical objects, God, his memories, history, science, even mathematics, but he cannot doubt that he is, in fact, doubting. He knows what he is thinking about, even if it is not true, and he knows that he is there thinking about it. From this basis he builds his knowledge back up again. He finds that some of the ideas he has could not have originated from him alone, but only from God; he proves that God exists. He then demonstrates that God would not allow him to be systematically deceived about everything; in essence, he vindicates ordinary methods of science and reasoning, as fallible but not false. List of rationalist philosophers: Christian Wolff René Descartes Baruch Spinoza Gottfried Leibniz Empiricism Empiricism is a theory of knowledge which opposes other theories of knowledge, such as rationalism, idealism and historicism. Empiricism asserts that knowledge comes (only or primarily) via sensory experience as opposed to rationalism, which asserts that knowledge comes (also) from pure thinking. Both empiricism and rationalism are individualist theories of knowledge, whereas historicism is a social epistemology. While historicism also acknowledges the role of experience, it differs from empiricism by assuming that sensory data cannot be understood without considering the historical and cultural circumstances in which observations are made. Empiricism should not be mixed up with empirical research because different epistemologies should be considered competing views on how best to do studies, and there is near consensus among researchers that studies should be empirical. Today empiricism should therefore be understood as one among competing ideals of getting knowledge or how to do studies. As such empiricism is first and foremost characterized by the ideal to let observational data "speak for themselves", while the competing views are opposed to this ideal. The term empiricism should thus not just be understood in relation to how this term has been used in the history of philosophy. It should also