The realist interpretation of the Uncertainty principle posits that reality is independent of the mind of the observer, therefore all objects must objectively have a pre-existing value for any possible measurement before the measurement is made. But because of the combination state of a quantum event (Schrodinger’s cat being simultaneously dead and alive before observation) there can be no pre-existing value for a possible measurement before the measurement is made, therefore no "thing" has a predefined existence in an unobserved state, which contradicts Materialism and reduces it to absurdity, i.e.that all things are composed of material, and that all emergent phenomena are the result of material properties and interactions, reality consists entirely of physical matter that is the sole cause of every possible occurrence, *(which cannot be true, according to realism, if no "thing" has a predefined existence in an unobserved state).

So if the Realist interpretation of the Uncertainty principle reduces Materialism to absurdity, why is Materialism still central to Physics?

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    I think that "materialism" is not the right word : "realism" is more apt. Having said that, some form of "realism" is intrinsic to scientific endeavor : if we do not believe that there is something "out there" and that there is a possbility of knowing it, why spend time with experiments and theories ? Regarding quantum mechanics interpretation problems, every "big" theory had some "philosophical" problem : for Newtonian mechanics, see absolute space and action at distance. If the "realist interpretation of the Uncertainty Principle reduces materialism[i.e.realism] to absurdity" ... 1/2 May 13, 2014 at 10:19
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    ...we can refine our interpretation of it, or try to find a new, better physical theory. 2/2 May 13, 2014 at 10:20
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    Most attempts to form very narrow definitions of something (e.g. what is "material") reduce to absurdity. So, don't do that. Ask instead: how can we use the word "material" and "materialism" to sensibly distinguish between different things (e.g. the "non-material")? For instance, admitting a wave function as "material" removes what I think is the core of your criticism, which is basically that material has to be perfectly localizable.
    – Rex Kerr
    May 14, 2014 at 21:58
  • i think it has to do with tradition. Materialism was the rejection of monotheism so seemed a good working assumption. Given the data it is hard to say why it is still central to physics, but perhaps it has become a habit. .
    – user20253
    Dec 16, 2019 at 14:47

3 Answers 3


The Copenhagen interpretation of quantum mechanics seems to imply that there is some important rôle for "observers" in the collapse of the wave function. Schrödinger gave his cat argument in an attempt to refute the Copenhagen interpretation by demonstrating that it leads to something ridiculous (a cat simultaneously dead and alive, and only "collapsing" to one state or another when the human opens the box).

As far as I know this argument has nothing to do with the uncertainty principle. The uncertainty principle is not mystical or particularly controversial. It is simply the statement that position and momentum are duals, and uncertainty principles also occur in classical systems (for example: the length and frequency of a sound are dual variables, the shorter a sound the more spread out its frequency spectrum must be, and a tone of a single frequency must be extremely long.)

I think almost all physicists are realists, as described in @MauroALLEGRANZA's comments, but they don't necessarily agree about what is real and what is just a model of reality. An interpretation of quantum mechanics makes philisophical assertions about what is and isn't real. If you look at the Wikipedia article about interpretations you will see that there are a dozen or so that are discussed and debated, and each makes different assertions about whether the wave function is "real" or just a mathematical convenience that models some other reality. They also all make different assertions about whether wave function collapse is real or is just an illusion brought about by quantum decoherence. Probably the most important sentence in the wikipedia article is:

No experimental evidence exists that distinguishes among these interpretations.

What most realists agree on, I think, is that there is something external to our minds, and that we all share a similar set of perceptions of things in the real world. That is: there are experiments we can perform and repeat and which we will all agree on the measured results.


What you have written about the uncertainty principle is false. In quantum physics, a system can be described in terms of Hermitian operators that change over time and these are called Heisenberg picture observables. When you do a measurement the result you see is not an observable but rather a real number that corresponds to one of its projectors. The reality that exists before the observations is described by the Heisenberg picture observables, not by a single number. See




I don't understand what position you're trying to refute since you haven't explained it and for all I know that position may be wrong, but your argument against it is wrong.


Quantum mechanics, which contains the uncertainty principle you and others mention here, applies when we try to measure or study things smaller than atoms. This means 1) you do not collapse your best friend's wavefunction when you notice him or her in a crowd and 2) you can simultaneously measure their position and speed to any level of accuracy you wish.

It has no application in describing the behavior of macroscopic objects in the everyday world inhabited by philosophers. There is hence no reason to expect that QM has anything substantive to say about the practice of philosophy.

  • So you believe there are no epistemic, ontic, or semantic implications of wave-particle duality?
    – J D
    Dec 16, 2019 at 15:36
  • wave-particle duality is a mathematical physics concept that has no implications for human thought or behavior. Dec 16, 2019 at 17:46

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