  A recent no-go theorem gives an extension of the Wigner's friend argument
that purports to prove that "Quantum theory cannot consistently describe the
use of itself." The argument is complex and thought provoking, but fails in a
straightforward way if one treats QM as a statistical theory in the most
fundamental sense, i.e. if one applies the so-called ensemble interpretation.
This explanation is given here at an undergraduate level, which can be edifying
for experts and students alike. A recent paper has already shown that the no-go
theorem is incorrect with regard to the de Broglie Bohm theory and misguided in
some of its general claims. This paper's contribution is three fold. It shows
how the extended Wigner's friend argument fails in the ensemble interpretation.
It also makes more evident how natural a consistent statistical treatment of
the wave function is. In this way, the refutation of the argument is useful for
bringing out the core statistical nature of QM. It, in addition, manifests the
unnecessary complications and problems introduced by the collapse mechanism
that is part of the Copenhagen interpretation. The paper uses the
straightforwardness of the ensemble interpretation to make the no-go argument
and its refutation more accessible.
