Hi Mark,
As to ''we cannot claim that particles (or waves or anything) exist'', that depends on what we mean with ''exist''.
If the very most fundamental law of a universe which creates itself out of nothing, without any outside interference, is the conservation law which says that what comes out of nothing must add to nothing -so everything inside of it, including space and time itself must cancel, so there's nothing left to see if we could actually step outside the universe, then in this sense, the universe has no physical reality, does not exist as 'seen' from without, so to say. This apparently doesn't prevent Big Bang Cosmology (BBC) make statements about it, a conceptual fallacy which, I'm afraid, completely disqualifies the 'theory'. If, as you agree, particles are both cause and effect of their interactions, then they only exist to one another if, to the extent and for as long as they keep interacting, so they do not exist to particles outside their interaction horizon.
Whether they exist to us and what nature we observe them to have, how we find them to behave when interfered with in an experiment is affected by the kind of experiment we subject them to, by the question we ask them. So while in classical mechanics, ''exist'' is a state, a noun, in a self-creating universe, in quantum mechanics, it is an activity, a verb: if we could cut of the continuous energy exchange between particles by means of which they express and preserve each other's properties, they'd vanish without trace, like the picture on a TV screen when we switch it off.
The problem of causality is that if you explain the mass of particles as originating in their interactions with the Higgs field or boson, then to explain the mass of the Higgs boson you need to invent a pre-Higgs particle, the mass of which to explain in turn requires a pre-pre-Higgs particle, ad infinitum. As I argue in my essay, cause is not fundamental. If we understand something only if we can explain it as the effect of some cause and understand this cause only if we can explain it as the effect of a preceding cause and the chain of cause-and-effect either goes on ad infinitum or ends/starts with some primordial cause or event which, as it cannot be explained as the result from a preceding event, cannot be understood by definition, then causality ultimately cannot explain anything. As in a self-creating universe particles create, cause one another, they explain each other in a circular way: here we can take any element of an explanation, any link of the chain of reasoning without proof, use it to explain the next link and so on, to follow the circle back to the assumption we started with, which this time is explained by the foregoing reasoning.
My objection to (temporal) causality (as opposed to ontological 'causality') is that it confuses cause and effect, or, to be more precise, that, if particles indeed are both cause and the effect of their interactions, we can no longer say that their mass precedes gravity between them, so instead of saying that particles contract because they have a certain constant rest mass (they somehow, mysteriously have been provided with) and gravity is attractive, we can as well say that they acquire mass only if and when they contract (agreeing with the uncertainty principle), that in doing so they power time. The idea of temporal causality, that cause precedes effect, only would make sense if we could determine what precedes what in an absolute sense, if we could look from outside the universe in, which BBC, in the concept of cosmic time, wants to make us believe is justified even though we cannot actually step outside of it. To regard it as an object we may imagine to observe from without only would be justified if particles only would be the source, and not also the product of their interactions.
In other words, to me ''ontological determinism'' seems to be a contradiction in terms.
Regards, Anton