Hi Malcolm,
Thanks for reading some of my paper, I really appreciate it.
I definitely lean more towards the realist side of Einstein's position.
"But it seems to me that you want to assert something more about that potential existence--that while potential events don't really exist until they happen, a particle's potential properties do really exist independently of whether they are observed or not. Would that be correct?"
I wouldn't call the properties "potential". The properties are always there. What "state they are in" is the potential. A particle possesses the property of spin as an actuality. It exists. Which direction the spin is pointing is the potentiality. An observer can only find out by doing a measurement.
I agree with you that "observation" is the crux of what measurement is all about. However, I assert that "existence" is apriori to "observation". One cannot observe without oneself existing first, nor can one observe something which does not already exist. The potentialities you mention are the "information" that observers can obtain about physical systems, and that information is limited by the non-zero commutation rules one obtains from the mathematics.
I have been coming at the measurement question in QM from a different perspective than most. I started with the axioms of SR, which are really just a limiting-case of GR, and then went looking for what I needed to get the rules of QM.
As it turns out, there are only a very few empirically-observed facts that are required. One then gets the Klein-Gordon RQM Equation, of which the Schoedinger QM Equation is just the non-relativistic limiting-case.
Superposition is indeed about potentialities, which is partial information about a system. When one performs the actual measurement, the resultant is always in only a single actual state.
I have been coming to the conclusion that the type of equation on has plays a role in whether one is talking about actualities and potentialities.