[lit-ideas] Re: Snow is white, and Grass is green (Collected Papers by Tarski)

  • From: Robert Paul <rpaul@xxxxxxxx>
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Thu, 27 Dec 2007 20:36:12 -0800

Some time ago I wrote

I should have been clearer and asked for an example of an 'illogical' statement that wasn't 'wrong.'

In response Andreas wrote

It took me a while to come up with the answer. Yes, there are examples of statements that both illogical and correct.

These come of course from quantum physics, where the impossible is possible. "A photon is a particle, not a wave, and a photon is a wave, not a particle." That's illogical, but... it's correct.

Its illogicality alas escapes me. It isn't easy to construct a model that has both wave and particle characteristics. It's known that in some experiments light will appear wavelake while in others it will appear to be made up of particles (the corpuscular theory). E.g., electron diffraction appears to be best described by assuming that the electron is a wave, and the photoelectric effect by assuming it's a particle. The idea that two different but complementary notions are needed to deal with quantum phenomena was first proposed by Bohr in 1927.

So, what we seem to have is that in certain experiments light behaves one way and in others another way. The judge, who is entirely disinterested rules that this is not an example of the type wanted, but is rather analogous to the case of Jekyll/Hyde who exhibited one sort of behaviour in certain settings and a different sort in different settings but never both in the same setting.

Case dismissed and plaintiff ordered to stand the next round.

Robert Paul
Michelson-Morley Professor of Loose Ends
Mutton College





The problem isn't quantum mechanics. The problem is in logic.


complementarity The concept that a single model may not be adequate to explain all the observations made of atomic or subatomic systems in different experiments. For example, electron diffraction is best explained by assuming that the electron is a wave (see de Broglie wavelength), whereas the photoelectric effect is described by assuming that it is a particle. The idea of two different but complementary concepts to treat quantum phenomena was first put forward by the Danish physicist Niels Bohr in 1927. See also light.


While it is not easy to construct a model that has both wave and particle characteristics, it is accepted, according to the theory of complementarity proposed by Neils Bohr, that in some experiments light will appear wavelike, while in others it will appear to be corpuscular. During the course of the evolution of wave mechanics it has also become evident that electrons and other elementary particles have dual wave and particle properties.
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