 Then in 1937, right after “Testability and Meaning”, Carnap was sent the typescript of Reichenbach’s Experience and Prediction for evaluation by the University of Chicago Press. In a long letter to Reichenbach he takes him to task for exaggerating the drawbacks of what Reichenbach chastises as the “disparity conception” of probability, whereby the “weight” (or “degree of confirmation” as Carnap also calls it) and probability (understood as relative frequency) are two separate (disparate) things. Reichenbach had gone so far in his submitted draft, apparently, as to claim that the disparity conception was not only the root of all philosophical error, but a form of metaphysics. Carnap says that he himself is not sure what side he is on regarding the disparity conception (and there is no reason to doubt this, in 1937, as far as we know), but he thinks both its acceptance and its rejection are perfectly compatible with empiricism, and advises Reichenbach to tone down his rhetoric.