Yes, that's right: you need <V'(x)> rather than V'(<x>). It's still the case that <x> does not follow a linear DE. My point was that while the SE is linear, th

Yes, that's right: you need <V'(x)> rather than V'(<x>). It's still the case that <x> does not follow a linear DE. My point was that while the SE is linear, that does not mean that everything derived from it is also linear. The original comment was asking where all the nonlinearities in the world could come from since the SE is linear. It was suggested that either QM is incomplete because it is linear or that we need wave function collapse to introduce nonlinearities. I think my counterexample shows that both of those suggestions are incorrect.