Re-evaluating Logical Positivism

This dissertation aims to depict the protocol sentence debate within the Vienna Circle, exhibit a real aspect of the Vienna Circle, and correct the false impression of the Vienna Circle. From the Perspective of the Protocol Sentence Debate, the Re-evaluation of logical positivism also has certain historical and contemporary significance.It has been thought that logical positivism hold a foundationalist conception of epistemology for a long time. Yet not only Carnap, Neurath and Schlick insist their own view on the foundation of knowledge, but also they arise a furious debate about the rock bottom of knowledge. During the course of the debate, their view underwent some revision to different degree.The foundation of knowledge concerned by the Vienna Circle focused on the protocol sentence proposed by Carnap. The protocol sentence amounts to what we now called observation report. Based on Neurath’s criticism on Aufbau and Carnap’s assimilation on Wittgenstein’s atom proposition, it was put forward by Carnap first. Aufbau is a fundamental work, and the received view on the Vienna Circle mostly resulted from the unilateral understanding of Aufbau. So, in order to correct the received view by the description of protocol sentence debate, we should first re-interpret the Aufbau.The background of Aufbau is neo-Kantism of the day. The project that Carnap pursued in Aufbau is closer to the Kantian and neo-Kantian conception of knowledge. The subject matter he concerned is the objectivity of scientific knowledge, the solution to it is the distinction between the form and the content. The strategy of anti-metaphysics in Aufbau is not based on radical empirism, but is neutral with respect to all the metaphysical parts of traditional epistemology.Criticized by Neurath on the methodological solipsism in Aufbau, and at the same time influenced by Wittgenstein, Carnap put forward protocol sentence for the first time. Neurath was not satisfied with the form of the protocol sentence proposed by Carnap, after accepting Neurath’s suggestion, Carnap bring forward another form of protocol sentence and he pointed out that the two forms of protocol sentences are equivalent in epistemology. This is the first stage of the protocol sentence debate, the two parties of this stage is Carnap and Neurath, the subject matter of the stage is the nature of the protocol sentence and its relation to the scientific system. At the end of this stage, the debate calmed down and Carnap agreed with Neurath at many aspects.Schlick objected the coherence theory of truth which is shared by Carnap and Neurath, and from then on the protocol sentence debate processed to the second stage. In this stage, Carnap was busy writing Syntax, so the debate was open out between Schlick and Neurath and they focused on the question of truth. Schlick hold correspondence theory of truth while Neurath hold the coherence theory.In the second stage of the protocol sentence debate, Carnap was influenced by Tarski and turned his study from syntax to semantics. After acceptance of the semantic definition of truth, Carnap distinguish ’truth’ from ’confirmation’, and the divided the test of protocol sentence into two steps, among of which is Neurath’s and Schlick’s view respectively. The protocol sentence debate is classified finally.The historical influence exerted by protocol sentence debate to the philosophy of science mainly consist in two ways, one is the elimination of psychologism; the other is that the framework of neo-Kantian epistemology has been running through the development of the philosophy of science. Based on this framework, we can add a meta-framework and re-establish the significance of philosophy in prevailing naturalism of our time.