Whitehead tells us that: "Every philosophical school in the course of its history requires two presiding philosophers. One of them under the influence of the main doctrines of the school should survey experience with some adequacy, but inconsistently. The other philosopher should reduce the doctrines of the school to a rigid consistency; he will thereby effect a reductio ad absurdum. No school of thought has performed its full service to philosophy until these men have appeared." (">Process and Reality, p. 89)