IMMANUEL KANT’S CRITIQUE OF PURE REASON

Presented by:Arnel O. RiveraLPU-Cavite

Based on the presentation of: Mr. Alexander Rodis

Lesson 4

A PRIORI AND A POSTERIORI KNOWLEDGEKant distinguishes between empirical and a

posteriori knowledge derived from sense experience and pure or a priori knowledge which is completely independent of experience.

1. A PRIORI KNOWLEDGE is the knowledge which comes before (prior to) sense experience and is therefore independent of sense experience. This is the emphasis of the rationalist.Ex. “Justice is good.”

“All triangles have three sides.”

2. A POSTERIORI KNOWLEDGE is knowledge which comes after (posterior to) sense experience and is therefore dependent on sense experience. This is the empiricist emphasis.

Ex. "There is a cup on this table." “All swans are white."

He establishes the two identifying marks by which pure or a priori knowledge may be recognized and distinguished from empirical or a posteriori knowledge:

1. Necessity

If we have a proposition which in being thought is thought as necessary, it is an a priori judgment; and if, besides, it is not derived from any proposition except one which also has the validity of a necessary judgment, it is an absolutely a priori judgment.

2. UniversalityExperience never confers on its

judgments true or strict but only assumed and comparative universality, through induction. We can properly only say, therefore, that so far as we have previously observed, there is no exception to this or that rule. If, then, a judgment is thought with strict universality, that is, in such manner that no exception is allowed as possible, it is not derived from experience, but is valid absolutely a priori

.

Empirical universality is only an arbitrary extension of a validity holding in most cases to one which holds in all, for instance, in the proposition, 'all bodies are heavy'. When, on the other hand, strict universality is essential to a judgment, this indicates a special source of knowledge, namely, a faculty of a priori knowledge.

Necessity and strict universality are thus sure

criteria of a priori knowledge, and are inseparable from one another. But since in the employment of these criteria the contingency of judgments is sometimes more easily shown than their empirical limitation, or, as sometimes also happens, their unlimited universality can be more convincingly proved than their necessity, it is advisable to use the two criteria separately, each by itself being infallible.

HE DISTINGUISHES BETWEEN ANALYTIC AND SYNTHETIC PROPOSITION OR KNOWLEDGEANALYTIC KNOWLEDGE They are knowledge that is true by

definition but not bearing on reality. When this type of knowledge is express in

the proposition, the predicate is contained in the subject.

They are logically true, and this means you could not deny them.

This is an A is A type of proposition.Ex. All barking dogs bark. All triangles have three sides.

SYNTHETIC KNOWLEDGE They are knowledge that is not logically certain,

but bearing on reality. In synthetic proposition, the predicate adds

something to the subject, and thus two ideas are “synthesized” in the proposition. It affirms or denies the existence of something and it informs us about things, it really does tell us something about the actual universe.

This is an A is B type of proposition.

Ex. It is snowing in Alaska. Water freezes at 32 degrees Fahrenheit Dogs bark.

SYNTHETIC A PRIORI KNOWLEDGEBoth rationalist and empiricist accept analytic

propositions as a priori certain and that they both at least some accept the synthetic proposition as a posteriori probable.

But can we possess any knowledge that is both a priori certain and synthetically informative?

IS THERE SYNTHETIC A PRIORI KNOWLEDGE?

ACCORDING TO KANT, YES!

He explains the nature of synthetic a priori knowledge both as being existentially informative and also bearing the marks of necessity and universality, something unaccountable for on the basis of experience.

REASONS:The ideas such as substance and causality do

not make their way into our minds through experience, but are “a priori categories of the understanding”, which molds and shape and in fact constitute our experience.

That is substance and causality are part of what we mean experience.Ex. “Every event must have a cause”

It is a synthetic truth but also possess a priori universality and necessity.

We have to experience things as causally related because that is the only way the mind create experience.

Although our knowledge begins with experience, it does not follow that it arises from experience. For it is possible that even our experience is a compound of that which we receive through impressions, and of that which our own faculty of knowledge (incited only by sensuous impressions) supplies from itself.

He insisted the role of a priori concepts as conditions of experience and the epistemological consequences of this:

“If by them only it is possible to think any object of experience, it follows that they refer by necessity and a priori to all objects of experience.”

Synthetic a priori judgments are characterized by :(a) an a priori element which is universal and necessary

(b) an empirical element which applies to the world.

“Synthetic a priori judgments are only possible when we relate the formal conditions of a priori intuition, the synthesis of imagination and the necessary unity of this synthesis in a transcendental apperception, to a possible empirical knowledge in general ”.

Thus there is in the "synthetic a priori" that which is not derived from experience, but yet applies to experience.

There are synthetic a priori judgments:(1) We have these in mathematics

Ex. 7+5=12(2) We have these in Physics: the concept of cause:

"Everything which happens has its cause." (3) We ought to have these in Metaphysics

"The world must have a first beginning.”

Metaphysics ought to contain nothing but a priori synthetic judgments - Thus the general problem of Metaphysics becomes the general problem of a priori synthetic judgments.

THE LIMITS OF REASONOne of the implications of Kant’s analysis is that we can know

nothing of reality as it is in itself (what Kant calls the noumenal world) but only as it appears to us through experience (he calls this the phenomenal world)

The reason is clear: The a priori categories or concepts of the understanding are constitutive of experience, and therefore they have no legitimate application beyond experience.

Causality for example applies only to objects of possible experience. And when we try to apply such concepts beyond experience, what results in nonsense and absurdities.

Thus if we have gained a priori certainty and universality for synthetic knowledge, it has been at the cost of giving up any possible knowledge of reality beyond space and time.