The strange world of quantum mechanics seems to have a natural appeal to irrational and foolish people like Postmodernists and others who deny objective empirical truth or the laws of thought.
In arguments with such people when you defend the reality of real objective empirical truths, you will frequently find such people immediately appealing to various weird phenomena in quantum mechanics to defend themselves. “Doesn’t quantum mechanics prove that there is no objective truth?,” they might say.
The use (or, rather, abuse) of quantum theory in this manner is deeply mistaken and fallacious, however, for the simple reason that what is true for, and actually does happen in, the infinitesimally small world of quantum mechanics need not be true at all for large objects in the macroscopic world in which human beings live. Let us take one example: abuse of quantum mechanics in attempts to dismiss the laws of logic.
For example, in the Schrödinger’s cat thought experiment, a cat is imagined as being both alive and dead simultaneously, because it is imagined as being in a state of quantum superposition.
Now, if it were true that a cat could naturally be in such a state, wouldn’t this disprove the Law of Noncontradiction, the law of logic that one cannot assert as true at the same time (1) a proposition p and (2) its negation (¬p) (or, that is to say, one cannot assert p ∧ ¬p without fatal self-contradiction)?
The answer to this lies in asking: how realistic is the Schrödinger’s cat thought experiment? Actually, there is no rational reason to think large macroscopic objects like cats could ever naturally be in a state of quantum superposition at all: the Schrödinger’s cat thought experiment is abstract, unrealistic and not possible in nature (Newton 2000: 166).
To cite some recent research here, some physicists have found evidence that time dilation effects caused by gravity cause the natural collapse of quantum superpositions in objects the size of molecules and larger objects, and that on a system like the Earth (with a given gravity), even with current technology, the size limit for an object in a state of quantum superposition is about a millimetre (which actually seems to be surprisingly large!). Of course, scientists might use better technology to overcome this natural limit in experiments and so create larger objects in a state of quantum superposition, but this is obviously a highly artificial activity that does not – as far as we know – happen in nature.
So the point is: whatever weirdness that happens at quantum scales in nature stays there and does not naturally intrude into our macroscopic world, so that it does not invalidate or refute the laws of logic as applied to the natural macroscopic world. Nor does it refute the arguments for real objective truth or the laws of logic when the latter are carefully restricted to the correct domain in which they operate: the natural macroscopic world of human life and large objects in it.
Gerry, Christopher C. and Kimberley M. Bruno. 2013. The Quantum Divide: Why Schrödinger’s Cat is either Dead or Alive. Oxford University Press, Oxford.
Newton, Roger G. 2000. Thinking about Physics. Princeton University Press, Princeton, N.J.
Pikovski, Igor, Zych, Magdalena, Costa, Fabio and Časlav Brukner . 2015. “Universal Decoherence due to Gravitational Time Dilation,” Nature Physics