The Swiss-American theoretical physicist Wolfgang Pauli (1900–1958) once stated (in a 1954 letter to Max Born) the following often-quoted words:
“[O]ne should no more rack one’s brain about the problem of whether something one cannot know anything about exists all the same, than about the ancient question of how many angels are able to sit on the point of a needle. But it seems to me that Einstein’s questions are ultimately always of this kind.”
Despite the bluntness and irony of that passage, it can still be argued that Pauli had a philosophical position on the reality that some scientists, philosophers and laypeople believe (as it were) hides behind our observations, experiments, tests, etc. So Pauli’s position can itself be interpreted as a philosophical position. In other words, Pauli wasn’t just offering a philistine scream of “shut up and calculate!”. (This is somewhat parallel to, for example, eliminative materialists and ontic structural realists whom are often deemed to offer “anti-philosophical” and “scientistic” positions while at the very same time being philosophers themselves.)
More specifically, Pauli rejected the opposition between reality itself (or “ultimate reality”) and what we can can know about reality (as did Niels Bohr). In other words, knowing “how Nature is” amounts to no more than a metaphysician’s dream. All we actually have is “what we can say about Nature”. And, at the quantum-mechanical level, what we can say is what we can say with the mathematics — in conjunction with experiments, tests, predictions, observations, etc. Consequently, just about everything else is analogical and/or imagistic in nature. Indeed the analogical/imagistic stuff can — and often does — mislead us.
Of course it can be asked whether or not Pauli was really talking about something that “one cannot know anything about” — or just being very impatient. (It must be noted that Pauli wrote these words in 1954 — long after the “quantum revolution” of the 1920s and 1930s.) Similarly, how did Pauli himself know that we could never know these things? After all, this is very unlike some of the perennially unsolvable problems in metaphysics. Here, instead, Pauli was discussing the very real (or concrete) experiments, data and observations which physicists (as it were) held in their hands and not the things which hide (as it were) underneath. And that distinction doesn’t even arise when it comes to most purely metaphysical disputes. This means that Pauli wasn’t turning his nose up at ancient philosophical problems as, say, Martin Heidegger and Ludwig Wittgenstein did. No, Pauli had a problem with something that was very new (i.e., well before the opening quote) — the interpretations of quantum mechanics. (The theoretical physicist Paul Dirac took a similar — though less sarcastic — stance on this when he stated the following: “The interpretation of quantum mechanics has been dealt with by many authors, and I do not want to discuss it here. I want to deal with more fundamental things.”)
So why was Wolfgang Pauli so quick off the mark with his remarks?
That said, perhaps Pauli wasn’t so quick off the mark at all.
Perhaps Pauli realised that the quantum-mechanical equivalents of angels sitting on the point of a needle would be forever beyond the grasp of physicists — by definition! After all, such arguments exist even when it comes to the macro (or “classical”) world. So they’re even more likely to be on the right track when it comes to quantum-mechanical phenomena.
So Pauli might have had incredible foresight on these matters.
Take the physicist David Finkelstein’s words on the problems with the many different interpretations of quantum mechanics.
He firstly tells us that “[q]uantum theory was split up into dialects” and that this was the case because “[d]ifferent people describe the same experiences in remarkably different languages”. Consequently, that widespread pluralism may seem fine and healthy … except for the fact that all “[t]his is confusing even to physicists”.
It was said earlier that Wolfgang Pauli’s position is philosophical precisely because if some x (or the supposed “reality”) is by definition always closed off to us (as well as the fact that we can never measure x or measurements always “disturb” x), then to question both the acceptance and importance of this hidden reality is a philosophical position. Sure, it can also be seen as a pragmatic position. Yet that too is still a philosophical position.
It’s of course the case that Pauli himself might well have believed that his position wasn’t at all philosophical. Or, at the least, he probably didn’t believe that it was a philosophical position which he could back up with lots of — philosophical! — arguments, conceptual analyses, etc.
But that doesn’t matter.
Other people can and did fill in the philosophical details which Pauli himself — qua physicist, not philosopher! — never got around to filling in.
So now take the words of physicist N. David Mermin (1935-) on this subject.
He tells us that quantum theory
“is so beautiful and so powerful that it can, in itself, acquire the persuasive character of a complete explanation”.
Is that a philosophical position? Well, both yes and no. Perhaps it doesn’t even matter what the answer to that question is — especially if we buy into the “shut up and calculate” mantra in the first place!
In any case, an anti-philosopher (or someone against the interpretation of QM) could argue that we have no need, right or philosophical justification to interpret the mathematical formalism/s, observations, data, experimental results, tests, etc. Of course it can be asked if it’s ever possible — even in principle — to completely bypass all interpretation in quantum mechanics. Probably not. So, in that case, we’d need to be specific as to what the interpretation is and what precisely it is that’s being interpreted. Indeed can we even say what it is (beyond the mathematics, etc.) without relying on at least a degree of interpretation?
Conclusion
All the above means that one can take a positive and pragmatic (or instrumentalist) position on all the many and various interpretations of quantum mechanics. Alternatively, one can take a pessimistic position on them.
The theoretical physicist Steven Weinberg (1933–1921) took the latter option. He wrote:
“My own conclusion is that today there is no interpretation of quantum mechanics that does not have serious flaws. This view is not universally shared. Indeed, many physicists are satisfied with their own interpretation of quantum mechanics. But different physicists are satisfied with different interpretations. In my view, we ought to take seriously the possibility of finding some more satisfactory other theory, to which quantum mechanics is only a good approximation.”
Now is Weinberg’s position philosophical in nature (just as with Wolfgang Pauli earlier)? Is Weinberg saying that it’s not all about observations, predictions, experiments, tests, etc. — it’s also about (Einstein’s) what is? In other words, is it a realist position on the interpretation of quantum mechanics?
Finally, one can even take a philosophical position against all interpretations of quantum mechanics. And, of course, all the interpretations of quantum mechanics are at least partly — often mainly — philosophical in nature. That’s right — even an outright rejection of all the interpretations of quantum mechanics will (or may ) still be a philosophical position. That’s especially the case if the person rejecting the interpretations of quantum mechanics believes that there’s something fundamentally suspect about the very idea of interpretation in the first place — at least as it’s usually found in quantum mechanics.
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