Logical Positivism

The logical Positivisme (or logical empiricism , neo-positivism , rational empiricism ) is a philosophical school clean with the Cercle of Vienna, founded by a joining together group of the scientists and philosophical Vienneses in the years 1920. Even if logical positivism is known for its radical theses, the Circle of Vienna were before a whole place of discussion between scientists, (Niels Bohr and Einstein occasionally intervened there) and philosophers who did not share the same convictions. One counts in particular in his rows Moritz Schlick, Hans Hahn, Otto Neurath, Carnap. The Circle of Vienna is the author of a proclamation, published in 1929 under the title the scientific design of the world , where it exposes his principal theses. One can also quote Ayer, which is probably that which best summarized the great theses of positivism logical, in its work Langage, Vérité and Logical .

The heritage positivist

Logical positivism, or neo-positivism is resulting from the Positivisme of Auguste Count and Ernst Mach. Positivism before is very related to the study of the Science. He seeks to break with the methods of the Théologie and the Métaphysique, which seek gods or mysterious causes to explain the phenomena. Positivism gives up giving causes to the phenomena and only seeks to give laws allowing to describe them and to predict them. On this point, logical positivism is perfectly faithful to the first positivism. It is a question of describing and of justifying the scientific discoveries by analyzing their step and their principles, to put the question how the world can be thus? (and not why it is thus?).

It is distinguished however from the positivism of Auguste Count by his Empirisme. In Count indeed, the significant experiment is very largely determined by the theories we have to include/understand it and no priority has. Whereas logical positivism considers that the feeling is the base of knowledge. The feelings are absolutely indubitable, and can thus, once formulated in a precise language, to be used to create scientific theories. The feelings must take the form of protocolar statements describing that a certain feeling was felt at such place and such time by such person. The protocolar proposals being absolutely true, science does not have any more but to include/understand the relations between these proposals to obtain a complete theory of physical reality. In that, Mach is the true precursor of the Circle of Vienna, because it defended already the idea that the concept of objective reality is not useful in science. Science makes according to him only in a rational way organize and specifies the relations between our feelings.

If sciences all can be based on the protocolar proposals, then sciences will have unit not only methodological but such a theoretical. There is no more reason of principle of distinguishing various sciences according to their field, as Count did it. Ultimement, various sciences should not make of it more that one, and this science will be physics. One calls this reduction of all only one sciences the Physicalisme. To be a physicalist, it is to affirm that physics makes it possible to explain all the phenomena of reality, including the life or the human thought.

In addition, logical positivism, just like positivism, are not without political concerns. Science, here, must be a design of the world, and not simply a discipline to which one can or not to deliver itself. The policy also must give up its dogmas metaphysics and be directed by scientific principles. Neurath, in particular, gave its political dimension to the Circle of Vienna.

Dimension " logique" positivism

The main new thing of the Circle of Vienna consists in its use of the Logique developed by Frege and Russell for the study of the scientific problems. Philosophy can then receive an entirely new and radical definition. It should not be a reflection absurdity on non-problems, it must concentrate on the study of science. More precisely, philosophy must be the logic of science, i.e. to examine the scientific theories, and to release the logical relations from them. It must show how the language of observation consisted the protocolar proposals provides the premises on which one can deduce the scientific proposals themselves.

Philosophy, in the direction of a logic of science, thus studies only the scientific speeches, which are the only true speeches of knowledge. And science is threatened by the Métaphysique, which is not a knowledge but a Mythe, reducible with Poésie. Carnap will say of the metaphysician that he is “a musician without musical talent”. However, the criticism which the logical positivism of metaphysics makes is completely original. This one does not reproach him such an amount of for not bringing any knowledge, critical traditional since Kant, to be a pure nonsense. Metaphysics does not have any significance. With the passage of positivism to logical positivism, the criticism of metaphysics passed from a criticism on its methods and its theses to a criticism on its significance itself.

Logic thus will use here to distinguish the direction (science) from the nonsense (metaphysics). But it is necessary to establish a criterion of distinction. This criterion is the theory verificationnist of the significance. He affirms that the significance of a statement is its method of checking. So that a statement has a direction, it is necessary thus that it relates to an observable empirical fact. If it is possible no to say if it is true or false, then it does not have any direction. Thus a proposal affirming " there is a Dieu" is neither true, nor distorts, but quite simply stripped of significance, because without consequences which would make it possible to check the assertion. The theory verificationnist can thus reject all the statements of metaphysics as stripped of directions since unverifiable. But it also has and especially an interest in science, where statements less indicators but so stripped of direction can hide.

On the other hand, the statute of logic does not achieve the unanimity in the Circle of Vienna. Schlick defends a design, near to Wittgenstein, which makes logic an activity and not a theory. Logic not being able anything to say the judicious one, it has only as a role to give explanations on the scientific proposals. Consequently, the theory verificationnist of the truth, which is supposed to distinguish the direction from the nonsense, would be itself a nonsense. Carnap defends an opposite vision of logic. Admittedly, logic does not speak about the objects of the world, but it is well a theory, it establishes the syntax of the scientific proposals. It is possible to speak about the speech without losing itself in metaphysics.

Critical of logical positivism

Karl Popper in particular in Logique of the scientific discovery will bring an important criticism of logical positivism about the verificationnist criterion. Popper considers that a scientific statement does not have to be verifiable but with being refutable. Indeed, there is not symmetry, because certain statements are refutable without being verifiable. All the statements which rest on a induction cannot be checked, because the number of possible situations is often infinite, but they can be refuted by only one contrary case with the prediction. Only, Popper is much less sensitive to the problem of the language and the distinction between direction and nonsense.

Quine, in the two dogmas of empiricism , is caught of it in a more radical way with the theses of logical empiricism. It tackles the idea that one can make a distinction sliced between statements synthetic, bearing on facts, and stated analytical, true under the terms of the only logical rules. For him, the concept of analytical is very badly defined. It even lets hear that logic can, it also to a certain extent, and in last authority, being revised, like any statement in fact. Because the second dogma, that of the reductionnism of very stated with statements relating to feelings (protocolar statements) is not bearable. Quine defends a approach holist: our statements face the experiment in block, and not one by one. When a statement is contradicted by the facts, it is thus not necessarily this statement which is faulty, it will be necessary can be to call into question a statement which was logically dependant for him, or several statements at the same time.

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