  The problem is with Quantum Mechanics for it seems there are entangled quantum states of many particles that attribute exactly the same intrinsic and relational properties to each of them. For example, the famous singlet state of two fermions, such as electrons, attributes to the pair the relation that their spins in any given direction are opposite to each other, but does not attribute a definite spin in any direction to either particle alone. Given that they may also be attributed exactly the same spatial wavefunction, as when they are both in the first orbit of an atom, for example, then such particles would seem to violate PII. This leads to a dilemma that was articulated by Steven French and Michael Redhead (1988); either quantum particles are not individuals, or they are individuals but the principle of individuation that applies to them must make reference to some kind of empirically transcendent haecceity, bare particularity or the like.