“When language goes on holiday”

Reflection on the problems of language in QM through Wittgenstein's philosophy

Resumo

The new discoveries of QM led to re-assessing, broadening the meanings of many physical concepts, and formulating a new logic that was no longer based on the classical principles of non-contradiction, identity, and causality. Heisenberg considered the classical logic and the conception of language expressed in the Tractatus Logico-Philosophicus inadequate for the understanding of the problems of language with which the physicists of the Copenhagen school had had to deal in order to define the foundations of Quantum Mechanics. On the contrary, he saw in Wittgenstein’s posthumous Philosophical Investigations the key to solving those problems. One may formulate a proportion and state that the use of language described in the Tractatus fits the use of language in Classical Mechanics, as the use of language described in PI fits the use of language in QM.

I interpret the reflections of the physicists of the Copenhagen school on the limits of language relative to QM by highlighting how the epistemological revolution of quantum physics shares a conception of language similar to that expressed by late Wittgenstein in PI. I also aim to explain why Heisenberg considered it inappropriate to subsume the propositions and concepts of QM under the rules of the propositional logic of Tractatus. I explain why the philosophy of language expounded in PI, which is based on language games and resemblance families, sheds a light on how and why QM has contributed to renewing existing concepts (such as space, trajectory, observer, etc.) and to formulate a new logic (quantum logic).