Abstract
Although we often see references to Carnap’s inductive logic even in modern literatures, seemingly its confusing
style has long obstructed its correct understanding. So instead of Carnap, in this paper, I devote myself to its
necessary and sufficient commentary. In the beginning part (Sections 2-5), I explain why Carnap began the study of
inductive logic and how he related it with our thought on probability (Sections 2-4). Therein, I trace Carnap’s
thought back to Wittgenstein’s Tractatus as well (Section 5). In the succeeding sections, I attempt the simplest
exhibition of Carnap’s earlier system, where his original thought was thoroughly provided. For this purpose, minor
concepts to which researchers have not paid attention are highlighted, for example, m-function (Section 8),
in-correlation (Section 10), C-correlate (Section 10), statistical distribution (Section 12), and fitting sequence
(Section 17). The climax of this paper is the proof of theorem (56). Through this theorem, we will be able to
overview Carnap’s whole system.