reason and practical reason into two separate spheres, the one a realm of certainty, the other a realm of human activity and doubt. Dewey discusses Kant’s solution as the most prevalent in modern times, and he attacks that solution as the theory that most clearly and destructively separates practice from experience. Finally, Dewey explores the dialectic idealism of Georg Wilhelm Friedrich Hegel, admiring Hegel’s concern with the practical, the imperfect realm, but questioning Hegel’s tendency toward seeking an ideal state of certainty. For Dewey, the danger in all modern philosophy is that method and content have been divided.

In lecture four, “The Art of Acceptance and the Art of Control,” Dewey begins to outline his theory of inquiry, a method that will replace these failed modern ones, a theory of inquiry that he bases on the scientific method. Dewey asserts that this method is so common, so pervasive, and so obvious that philosophers have not recognized it or created a theory of knowledge around it. This theory of knowledge is based on scientific method. Dewey also asserts, as a caveat, that modern science too often views data as unrelated particulars divorced from human experience. To gain knowledge, however, people must advance a method that explains how they learn from experience. Experience is the only source of knowledge—for Dewey, experiences are what exist.

To prove that reason cannot operate independent of experience and that knowledge of the physical realm cannot exist independent of reason, Dewey considers the interconnection of mathematical principles and the world of experience, arguing that mathematical principles—ideas that come close to pure abstraction—only exist in the physical realm: “Mathematical space is not a kind of space distinct from so-called physical and empirical space, but is a name given to operations ideally or formally possible with respect to a thing having spacious qualities.” To illustrate his method further, Dewey analyzes the analogy of a good doctor diagnosing a patient’s illness, a technique that Dewey posits as exemplifying his epistemology.

Doctors have ideas and theories that they learned in school and from books, but this abstract knowledge is not enough—a good doctor must also have experience. When doctors see patients, they form hypotheses concerning the patients’ illnesses, but the doctors must then perform experiments to confirm or reject these hypotheses. With each case and with each experience, the good doctor gains knowledge. Thus, experienced doctors form better hypotheses. Essential to this method is “the appreciation and use . . . of direct experience.” At the core of Dewey’s philosophy is his epistemology, his theory of how people know what they know. This theory has been labeled instrumental logic, but it is really a commonsense theory of scientific method. Dewey’s theory relies on reflective experimentation.

In his ninth lecture, Dewey returns to the question of certainty and the method that should be employed in situations in which one is uncertain. Dewey states that uncertainty arises in new situations and that humans wish to quell the fear or doubt that arises in such situations. One may alleviate uncertainty quickly by retreating to an abstract realm. An example of this would be a person who, when in trouble, prays, hoping that the prayer will solve the problem. Humans want to eliminate uncertainty or fear quickly. Dewey argues against such methods. The intelligent person has a delayed reaction to uncertainty, a reaction that allows uncertainty to linger. People should experiment in an uncertain situation, and this is done by means of manipulation. By experimenting, people change their relationship to the situation that is creating fear and, perhaps, create a new situation from which they can learn.

In his tenth lecture, “The Construction of Good,” Dewey extends his epistemology into an ethics by arguing that values are not absolutes that exist prior to and separate from a particular circumstance. The good arises from what one experiences in a specific situation, and this will change as conditions change. Again, method is essential to determine the good. People cannot separate the means from the end—this would be the same as separating practice from theory. People must know how and why something is good, and this consideration returns them to a particular situation, a particular problem. Dewey’s epistemology draws on a commonsense means of knowing, and his ethics draws on a practical means of valuing. He believes that philosophers have spent too much time searching for the good in a permanent, transcendent realm, while most people find value in particular experiences.

Dewey ends The Quest for Certainty with the lecture, “The Copernican Revolution.” Nicolaus Copernicus, relying on scientific experimentation, asserted that the sun, not the earth, was at the center of the solar system. Thus, he displaced the Ptolemaic notion that dominated the Middle Ages. Kant compared himself to Copernicus, saying that he created a revolution in philosophy as Copernicus created one in science, but Dewey maintains that Kant’s philosophy in maintaining a realm of pure reason is Ptolemaic in that it places human beings and their quest of certainty at the center of the system. Dewey, on the other hand, sees himself and other American pragmatists performing a Copernican revolution by basing philosophy, education, and social theory on experience, and by privileging a method of inquiry that does not ignore human experience.

The Quest for Certainty is a significant work in that it presents the mature theory and method of an influential American philosopher. The lectures delineate his objection to previous philosophy, his own theory of inquiry, and his ethics. These lectures do not explore his authoritative theories of aesthetics, education, and politics. Dewey, in other works, extends his method of experimental inquiry into education, advocating experimentation as the way to knowledge. Dewey also argued that the active exchange of ideas that should occur in school could model the democratic process. A society based on his theories of education and democracy would form a community of free inquirers who test their ideas in a public forum, not in an abstract or isolated realm.