  In the present paper, the decision problem of the Schr\"odinger equation
(asking whether or not a given Hamiltonian operator has the nonempty solution
set) is represented as a logical statement. As it is shown in the paper, the
law of excluded middle would be applicable to the introduced statement if and
only if quantum fundamentalism (asserting that everything in the universe is
ultimately describable in quantum-mechanical terms) held. But, since the
decision problem of the Schr\"odinger equation is in general undecidable, such
a statement is allowed to be other than true or false, explicitly, it may fail
to have truth values at all. This makes possible to abandon the law of excluded
middle together with quantum fundamentalism in the proposed intuitionistic
interpretation of quantum mechanics.
