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Michael Friedman’s Analysis of Logical Positivism
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4. New Interpretations of Logical Positivism.

Michael Friedman’s analysis of logical positivism.

In recent years the interest of scholars in the philosophy of logical positivism is considerably grown, and new original publications has been dedicated to the d evelopment of logical positivism. New interpretations of the philosophy of logical positivism have been proposed. Of particular interest is Michael Friedman's analysis of logical positivism, according to which the "central philosophical innovation [of logical positivism] is not a new version of radical empiricism but rather a new conception of a priori knowledge and its role in empirical knowledge" (Friedman, Michael, Reconsidering Logical Positivism, 1999, pag. xv).

Another source of interest is the explication of the influence that Kantian philosophy exerted on the origin and development of logical positivism. According to Friedman, logical positivism, instead of adopting a purely empirical vision of science, recognized the necessity of non empirical a priori principles by means of which scientific theories can receive an empirical interpretation and therefore can be tested. Friedman calls these principles "relativized a priori principles" (Friedman, Michael, Reconsidering Logical Positivism, 1999, p. xv). As explained by Friedman, the necessity of such a priori principles is explicitly recognized by Hans Reichenbach in his first work on the philosophy of the theory of relativity, Relativitätstheorie und Erkenntnis Apriori, 1920. Reichenbach formulates the now well known distinction between axioms of connection and axioms of coordination. The former are empirical laws, formulated using concepts which are empirically well defined; the latter are non empirical principles which give an empirical interpretation to the theory. Every scientific theory requires a set of axioms of coordination. With respect to a given theory, the axioms of coordination are constitutive of the object of the theory, in the sense that without the axioms of coordination the theory has no empirical meaning. For example, in classical mechanics and in special relativity, the metric of the space-time is an axiom of coordination, that is the Euclidean structure of the geometry is assumed a priori valid. In the general relativity, on the contrary, the space-time metric is empirically verifiable, while a suitable space-time topology is assumed a priori.

The main difference between Kantian synthetic a priori and Reichenbach’s axioms of coordination is that according to Kant synthetic a priori principles are necessarily valid and unrevisable, while Reichenbach acknowledged that axioms of coordination are subjected to modifications with the evolution of scientific knowledge. For instance, Euclidean geometry is a priori relatively to Newtonian mechanics, while it is an empirical false theory in general relativity. Synthetic a priori knowledge, in Kantian philosophy, has two main features: first, it is necessarily and universally valid; second, it is constitutive of the object of knowledge (transcendental in Kantian terminology). Reichenbach accepted the presence, in scientific theories, of a priori principles which are constitutive of the empirical objects, but he denied that these principles are unrevisable.

According to Friedman, "in Carnap's Logical Syntax of Language we find a revival of the relativized a priori in something very like Reichenbach’s original sense" (Friedman, Michael, Reconsidering Logical Positivism, 1999, p. 68). Friedman suggests that "Carnap's L-rule or analytic sentences can be profitably viewed as a precise explication of Reichenbach's notion of the constitutive or relativized a priori" (ibid., p. 69).

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