  In a series of recent papers, Simon Saunders, Fred Muller and Michael
Seevinck have collectively argued, against the philosophy of quantum mechanics
folklore, that some non-trivial version of Leibniz's principle of the identity
of indiscernibles is upheld in quantum mechanics. They argue that all particles
-- fermions, paraparticles, anyons, even bosons -- may be weakly discerned by
some physical relation. Here I show that their arguments make illegitimate
appeal to non-symmetric, i.e. permutation-non-invariant, quantities, and that
therefore their conclusions do not go through. However, I show that
alternative, symmetric quantities may be found to do the required work. I
conclude that the Saunders-Muller-Seevinck heterodoxy can be saved after all.
