Categorizing Knowledge:
The Distinctions Which Enable us to Express 
the General Problem of Pure Reason.

Jonah Bossewitch
PHI 304
Professor Beatrice Longuenesse
October 12, 1994

	In order to understand the problem that drove Kant to write the Critique of Pure Reason, it is crucial to understand two distinctions.  First, the distinction between  a priori and a posteriori cognition, and second, the distinction between synthetic and analytic judgment.  These distinctions  are the very first items that Kant addresses and this is indicates that Kant considers these concepts of central importance to the Critique.  It is with these concepts that Kant expresses the fundamental problem that the Critique sets out to solve.  Without an appreciation of these ideas it is impossible to understand why this book was even written.
	The introduction to the critique is an attempt to organize our knowledge.  Kant's first distinction is between pure and empirical knowledge, or a priori and a posteriori knowledge.  This distinction is an epistemological distinction that is based upon the origin of the knowledge.  He is dividing knowledge into two classes: a priori knowledge is "knowledge absolutely independent of all experience." ;  and, a posteriori knowledge is "knowledge possible only... through experience."  (B3)  What this means is that all a priori knowledge is logically necessary (it could not be otherwise) and universally  true.  As opposed to a posteriori knowledge which is contingent (it might not have been true).  Kant does not deny that all knowledge must begin with sense experience.  However, how our knowledge begins, and where our knowledge originates are two different questions.  Kant understands this is by thinking of objects that affect our senses as triggers, that can activate our knowledge not derived from sense experience.  Our a priori knowledge is not accessible prior to sense experience, but its origin is prior to sense experience. 
	The second distinction that Kant makes is a semantic distinction based upon the content of the knowledge.  In particular, the distinction is dependant on the relationship between the subject and the predicate of the judgement.  Again, he is dividing the knowledge into two classes: in an analytic judgement "the connection of the predicate with the subject is through identity... adding nothing through the predicate to the concept of the subject.";  whereas, a  synthetic judgment "add[s] to the concept of the subject a predicate which has not been in any wise thought in it, and which no analysis could possibly extract from it;" (A7/B11)  The analytic-synthetic distinction is dependant upon the notion of containment.  In an  analytic judgement the predicate is contained in the subject, while in a  synthetic judgment the predicate is not contained in the subject ( it "adds something" to the subject).  

	When these two distinctions are combined the result is four categories of knowledge.  These categories are analytic a priori, synthetic a priori, analytic a posteriori, and  synthetic a posteriori.  Types of  analytic a priori knowledge include entailments, identity statements, tautologies, and definitions.  A typical example of one is "All bachelors are unmarried."  Since part of being a bachelor is being unmarried, the predicate is contained in the subject and the statement is analytic.  Also, since knowledge of this statement is possible independent of experience the statement is a priori.   Synthetic a priori knowledge is the kind that is especially relevant to the Critique, and this kind of knowledge includes Mathematics, Logic, the pure forms of sensible intuition, moral judgements, and Metaphysics.  Kant's favorite example of synthetic a priori knowledge is geometry.  For instance, Kant brings up the properties of the isosceles triangle (BXII) and argues that these properties were not "read off."  Rather, they known independent of experience making them a priori, and at the same time contribute new ideas to the subject (the isosceles triangle) making them synthetic.  There are no examples of  analytic a posteriori knowledge since a statement that is analytic leaves nothing to be discovered through experience.  Finally, examples of  synthetic a posteriori knowledge are all empirical statements.  "Barry is a bachelor" is a piece of synthetic a posteriori knowledge since the predicate (bachelor) does add something to the subject (Barry), but the statement is not necessary and universal.  Barry could have  been married, and the only way that we know he is not is through experience.  Not all philosophers agree with Kant's organization of knowledge.  Some question whether there actually is a distinction between synthetic and analytic, some challenge Kant's categorization of some types of knowledge, and some deny the existence of synthetic a priori knowledge.  However, it is crucial to understand Kant's organization of knowledge, since it is presupposed in the Critique.
	If we accept Kant's organization of knowledge, there is a fundamental question that demands an answer.  First, Kant argues that the underlying principles of Mathematics, Science, and Metaphysics are synthetic a priori.  Then he states that "since theses [Mathematics and Physics] sciences actually exist, it is quite proper to ask how they are possible;  for that they must be possible is proved by the fact that they exist."  (B21)  So, given that (1) Kant's organization of knowledge is valid, and (2) that the underlying principles of Mathematics, Physics, and Metaphysics are synthetic a priori, and (3) that Mathematics and Physics actually exist, it is valid to conclude that synthetic a priori judgements are possible.  This conclusion leads directly to the general problem of pure reason:  How are a priori synthetic judgements possible?
	This general problem of pure reason is considered by Kant to be the fundamental problem of his critical philosophy.  By this he means that if he can solve this problem he can solve all of the other problems that he considers important.  Kant feels that "much is already gained if we can bring a number of investigations under the formula of a single problem."  It may be possible to find an alternative problem whose solution also happens to solve our other problems, but this does not detract from the fundamental nature of this problem with respect to Kant's Critique.  It's importance is clear when we consider the implications of Kant's success or failure in finding a solution.  If Kant  can not discover how a priori synthetic judgements are possible, not only is "all that we call metaphysics a mere delusion" (B20), but the foundations of Mathematics and Physics are also demolished.  On the other hand, if Kant can discover how a priori judgments are possible, not only will he have explained how Mathematics and Physics are possible, he will also have demonstrated that Metaphysics is possible.  Without the possibility of Metaphysics there is no way to meaningfully discuss God, freedom, and immortality.  Such a conclusion is unacceptable to Kant, and consequently lends a sense of urgency and sincerity to his work.  Kant gives such prominence to the general problem of pure reason because it is fundamental to his Critique, which he believes is fundamental to all of us.
	Kant likens his analysis of the problem of pure reason to the Copernican hypothesis.  This analogy between the Critique and the Copernican revolution works in more than one way.  On one level, the Copernican revolution overthrew the accepted paradigm that the earth was the center of the universe, and the Kantian revolution overthrew the accepted paradigm that representations of objects conform to the objects as they are in themselves.  Both revolutions are characterized by a shift in perspective.  The Copernican revolution takes us from an internal reference frame (Earth centered) to an external reference frame (Sun centered), while the Kantian revolution takes us from an external reference frame (objects in themselves) to an internal reference frame (our mode of representation).  The analogy can be tightened by saying that both revolutions are characterized by a realization that appearances do not necessarily correspond to reality.  For Copernicus it meant convincing people that although it sure looked like everything else revolved around the Earth, a better explanation (one that fits with Newtonian Physics) was that the Earth revolved around the sun.  For Kant it meant convincing people that, although it sure seemed that our representations conformed to things as the are in themselves, a better explanation (one that allows us to answer the general problem of pure reason) is that "these objects of appearances, conform to our mode of representation." (BXX)  Finally, one analogy which we can assert with certainty is that the Kantian revolution was as monumental and pivotal for Metaphysics as the Copernican revolution was for Physics.