ce of God and the validity of the Christian religion. Although he saw himself as answering old and vexing questions in the Christian tradition, he actually created a radically new way of approaching the world: systematic doubt. The hallmark of Cartesianism is setting up a formal system of doubt, that is, of questioning all propositions and conclusions using a formal system. Once one has arrived at a certain piece of knowledge, that piece of knowledge then becomes the basis for clearing up other doubts. Descartes systematic doubt became the basis of the Enlightenment and modern scientific tradition. One begins with a proposition, or hypothesis, that is in doubt and then tests that proposition until one arrives, more or less, at a certain conclusion. That does not, however, end the story. When confronted by the conclusions of others, one's job is to doubt those conclusions and redo the tests. Once a hypothesis has been tested and retested, then one can conclude that one has arrived at a "scientific truth." That, of course, doesn't end it, for all scientific truths can be doubted sometime in the future. In other words, although scientists speak about certainty and truth all the time, the foundational epistemology is skeptical: doubt anything and everything. ...
