 As early as Logical Syntax (Carnap 1934/1937, 244/316–17) Carnap had suggested that Wittgenstein’s remarks in the Tractatus about ranges (Tractatus, 4.463) might be a starting point for thinking about probability. By 1945 Carnap also distinguished the two approaches described here, insisting that they were not competitors but were attempting to explicate two different concepts of probability. One need not choose one as the only concept; both concepts were useful. Reichenbach, by contrast, never conceded that both concepts were needed and insisted that his frequency notion could serve all epistemic purposes for which any notion of probability is needed.