Synthetic a priori

In Philosophy, the synthetic judgments or proposals a priori are a type of Proposition distinguished from the proposals Analytique S and synthetic proposals a posteriori . Accesses appeared in the philosophy of Emmanuel Kant, this type of judgment is characterized by the combination of two apparently opposite natures: they are justified by the intuition, and are however a priori , i.e. independent of the Expérience. This very particular kind of proposal thus has the appearance of a third term between the truths analytical, necessarily a priori , and the truths in fact, drawn from the observation. So of other philosophers after Kant reaffirmed the existence of synthetic judgments a priori , their reality was called today into question. Bracket between the precursors of analytical-synthetic division and the dominant contemporary design, the golden age of the synthetic judgments a priori seems finished today.

A Kantian innovation

One generally differentiates two types of proposals.

proposals relating on the facts, the experiment.
true proposals independently of the experiment.

In spite of the specific nuances to these authors, one appreciably finds such a diagram in the philosophy of David Hume and Gottfried Leibniz. The originality of Kant will be to introduce another type of judgment, of which he will seek has to establish reality in his Critique of the pure reason . It is on this occasion that it gives a series of definitions on the analytical one and the synthetic one which will mark the history of philosophy in the centuries according to.

According to Kant, a judgment is analytical when the concept of sound Prédicat is included in that of its subject. Such a presentation is based on the traditional structure of the proposal, which regards very stated as made up of a Sujet and a predicate. A judgment is then analytical when one obtains it by analysis of the concept of the subject, without nothing outside being added. The example taken by the philosopher of Konigsberg is that of the body: “any body is wide” is an analytical proposal, because the space extension is supposed by the concept of body. A body can have various forms well, or not to have a weight, it is inconceivable that it does not have any extent. Insofar as only the comprehension of the concept is concerned, the analytical judgments are also a priori .

The synthetic judgments them make it possible to increase knowledge. A proposal affirming that any body has a Poids, for example, adds with the concept of body that of weight. The concept of the predicate is not included in that of the subject, it has no more simple analysis there: an additional element appeared. The synthetic judgments will be then for Kant of two kinds:

synthetic a posteriori
synthetic a priori .

The first are recognized in the philosophical tradition: they are the proposals relating to the facts. The seconds are a Kantian innovation, and it will consequently be a question for their creator of justifying of their legitimacy. This justification brings then within Kantian philosophy. What will differentiate synthetic judgment a posteriori and a priori , it is the type of Intuition to which they will appeal.

A synthetic judgment a posteriori will imply necessarily the intervention of a sensory intuition, a synthetic judgment a priori will suppose only that of the pure Intuition. The pure intuition being composed of the Time and the space, the last type of judgment will recourera there obligatorily in one way or another. Kant will support that the Arithmétique calls upon the internal direction (time), the Géométrie it with the external direction (space).

Specific fields

The judgments synthetic a priori primarily carry on two fields

the Mathématiques
the Métaphysique.

The mathematical proposals are according to Kant synthetic a priori , it cannot be simply analytical. The proposals of metaphysics criticizes are also synthetic a priori . Contrary to the dogmatic metaphysics which is lost in contradictions, critical metaphysics that Kant proposes is supposed it to have more solid bases, and is based on the possibility of synthetic judgments a priori .

A critical perenniality

Removed from its Kantian formulation too dependant on traditional logic and its presupposed metaphysics, the distinction between synthetic a posteriori and a priori will be reassumed by other personalities. Among those Ci one notes Gottlob Frege, of which the criticism of the Kantian position on the arithmetic mask often the basic agreement on the statute of the geometry. In a rather ironic way, the demonstration frégéenne of the arithmetic analycity of the laws contributed to discredit the synthetic judgments a priori . Frege however recognized them, by limiting them to the field of the geometry.

The discovery of nonEuclidean geometries during the 19th century (by Lobatchevski, Bolyai, Riemann) then the Theory of relativity which affirms that the geometry of real space is nonEuclidean will carry a fatal blow to the belief in the existence of synthetic judgments a priori . Thus, the logical positivists (like the first Wittgenstein or Carnap) base their thought on the negation of such judgments, by affirming that any knowledge comes from the experiment and that the laws (or intuitions) logical do not say anything on the world, they are pure Tautologie S.

Random links: