Another observation of the untenability of Positivism made by Cornelius Lanczos

Here's a direct quotation from Lanczos:

The sober, practical, matter-of-fact nineteenth century_ which carries over into our day_suspected all speculative and interpretative tendencies as "metaphysical" and limited its programme to the pure description of natural events....
However, philosophical trends float back and forth and the last word is never spoken. In our own day we have witnessed at least one fundamental discovery of unprecedented magnitude, namely Einstein's Theory of General Relativity, which was obtained by mathematical and philosophical speculation of the highest order. Here was a discovery made by a kind of reasoning that a positivist cannot fail to call "metaphysical." and yet it provided an insight into the heart things that mere experimentation and sober registration of facts could never have revealed. The Variational Principles of Mechanics, xxiv.