Methods of Investigation Like other thinkers of the time, Descartes was attracted to the notion of a scientific method of investigation, which when followed would enable him to make new discoveries and push the boundaries of knowledge.
INTRODUCTION Rationalism is the philosophical view that knowledge is acquired through reason, without the aid of the senses.
Mathematical knowledge is the best example of this since through rational thought alone we can plumb the depths of numerical relations, construct proofs, and deduce ever more complex mathematical concepts.
Finally, Rule 4 is to review: to make enumerations so complete and reviews so general that I should be certain of having omitted nothing (ibid).
Descartes recognized that if he actually began by rejecting all of his previous views, he would be temporarily entering a no mans land in which he could believe or trust nothing until his final system of knowledge was well underway. Should he become an atheist, a drug peddler, or bank robber?