I am against “interpretations” of Quantum Mechanics (QM) in a sense in which John Bell [1] was against measurement in QM and Travis Norsen [2] is against realism in QM. Bell was not against doing measurements, he was against using the concept of measurement as a central concept in quantum foundations. Norsen does not think that realism does not exist, he thinks that the existence of realism is so obvious and basic that one should not even talk about it. In a similar spirit, I do not think that physicists should not study interpretations, I think that it is misleading to talk about interpretations as something different from theories. The titles “Against measurement” [1] and “Against realism” [2] were chosen by Bell and Norsen with an intention to provoke, by imitating the provocative style of Paul Feyerabend – the famous philosopher of science who was “Against method” [3]. My intentions here are of a provocative nature too.

Physicists often say that in physics we need theories that make new measurable predictions and that we don’t need interpretations that make the same measurable predictions as old theories. I think it’s a nonsense. It’s a nonsense to say that theories are one thing and interpretations another. The interpretations are theories. Making a distinction between them only raises a confusion. So we should ban the word “interpretation” and talk only about the theories.

Let me explain. Suppose that someone develops a theory called T1 that makes measurable predictions. And suppose that those predictions were not made by any previous theory. Then all physicists would agree that T1 is a legitimate theory. (Whether the predictions agree with experiments is not important here.) Now suppose that someone else develops another theory T2 that makes the same measurable predictions as T1. So if T1 was a legitimate theory, then, by the same criteria, T2 is also a legitimate theory. Yet, for some reason, physicists like to say that T2 is not a theory, but only an interpretation. But how can it be that T1 is a theory and T2 is only an interpretation? It simply doesn’t make sense. To resolve that issue, one might say that both T1 and T2 are interpretations. Fine, but then what is the theory? T1 was a legitimate theory before someone developed T2, but now T1 ceased to be a theory just because someone developed T2? It doesn’t make sense either. Or perhaps the theory is just the set of final measurable predictions of T1 and T2, while all the other “auxiliary” elements of T1 and T2 are the “interpretation”? It doesn’t make sense either, because there is no theory in physics that deals only with measurable predictions. All physics theories have some “auxiliary” elements that are an integral part of the theory. Or perhaps an interpretation is a theory that emphasizes philosophical aspects? I think this is what most physicists really mean by interpretation, even if they don’t want to say it explicitly. The problem with this definition is that it cannot be put into a precise form. All theories have some philosophical aspects, some theories more, some less. So exactly how much of philosophy a theory has to have to call it an interpretation? It’s simply impossible to tell. And where exactly is the borderline between philosophy and non-philosophy? There is no such borderline. To conclude, we can talk about a theory, we can distinguish the measurable predictions of the theory from other elements of the theory that cannot be directly measured, but it doesn’t make sense to distinguish an interpretation from a theory. There are no interpretations of QM, there are only theories. References: [1] J. Bell, Against measurement, https://m.tau.ac.il/~quantum/Vaidman/IQM/BellAM.pdf [2] T. Norsen, Against “realism”, http://de.arxiv.org/abs/quant-ph/0607057 [3] P. Feyerabend, Against method, https://en.wikipedia.org/wiki/Against_Method