In this article I expound an understanding of the quantum mechanics of
so-called "indistinguishable" systems in which permutation invariance is taken
as a symmetry of a special kind, namely the result of representational
redundancy. This understanding has heterodox consequences for the understanding
of the states of constituent systems in an assembly and for the notion of
entanglement. It corrects widespread misconceptions about the inter-theoretic
relations between quantum mechanics and both classical particle mechanics and
quantum field theory. The most striking of the heterodox consequences are: (i)
that fermionic states ought not always to be considered entangled; (ii) it is
possible for two fermions or two bosons to be discerned using purely monadic
quantities; and that (iii) fermions (but not bosons) may always be so
discerned.Comment: 58 pages, 5 figure
