Elegant derivations from first principles — which often proved tractable only when applied to idealized situations — were of little value to the many colleagues who needed to fine-tune electronics components for maximum efficiency... Schwinger rearranged his equations in terms of measurable inputs and outputs, just as his engineering colleagues at the Rad Lab had done with real-world electronics. By recasting the calculation, Schwinger managed to calculate the effects of quantum fluctuations on the electron's energy levels and obtain an answer that matched Lamb's measurement to an extraordinary precision. As it turned out, Japanese physicist Sin-Itiro Tomonaga had accomplished the same goal a few years earlier. Tomonaga's work on radar during the war had proven similarly essential to his theoretical approach. This war-forged pragmatism produced enormously impressive research and influenced a generation of leading scientists... Anything that smacked of 'interpretation', or worse, 'philosophy', began to carry a taint for many scientists who had come through the wartime projects. Conceptual scrutiny of foundations struck many as a luxury. The wartime style was reinforced in the United States by exponentially rising university enrolments after the war. The new classroom realities left little space for informal discussion of philosophy or foundations. The Rad Lab rallying cry of “Get the numbers out” shaded into “Shut up and calculate!”
Kaiser, David. "History: Shut up and calculate!." Nature 505.7482 (2014): 153-155.
You can’t blame most physicists for following this ‘shut up and calculate’ ethos because it has led to tremendous developments in nuclear physics, atomic physics, solid state physics and particle physics.
Jean Bricmont, quoted in Zeeya Merali, "What is Really Real?", Nature (2015)
Thinking about foundations pays off in the long run. David Mermin once summarized a popular attitude towards quantum theory as “Shut up and calculate!”. We suggest an alternative slogan: “Shut up and contemplate!”
Lucien Hardy and Robert Spekkens, "Why Physics Needs Quantum Foundations" (2010)
