The Limits of Knowing What Exists: On the Issue of Correspondence in Physics within the Vienna Circle

This article examines the possibility of knowing what exists and the limits of epistemology within the Vienna Circle’s physics-centered approach. Rather than addressing all members of the Circle, the study focuses on the views of prominent representatives, including Mach, Schlick, Neurath, Reichenbach, and Carnap. Although these thinkers differed on particular issues, they broadly agreed that knowledge of what exists requires definable limits, that these limits are established through correspondence with physics, and that only propositions verifiable through observation and experiment are meaningful. Within this framework, the limits of knowledge are defined epistemologically and are closely identified with physical reality. Physics thus corresponds both to a bounded universe and, more broadly, to an overarching conception of the unity of the sciences. This position opens the way to treating physics as the object, source, and criterion of truth concerning what exists. This approach, championed by the Vienna Circle, was systematized through “the scientific world-outlook” manifesto and institutionalized around the ideal of unified science. The central concern of this article is therefore to examine the ontological, epistemological, and methodological structure underlying the identification of limits imposed by correspondence in physics with the limits of epistemology through the principle of verifiability.