Benjamin
Thanks for you prompt response, and the constructive nature thereof.
Re 1: But this is not what I am saying. We can only investigate a specific form of existence. In short!:
Any form of existence invokes the possibility of an alternative, (ie if A, there is always the logical possibility of not-A). But, any form of existence other than our reality is inherently unknowable, since we cannot transcend our existence. Therefore, we can only analyse our reality. That being existence in the form of what we can detect (either directly or indirectly), which is dependent on the sensory processes.
Therefore, our reality comprises those physically existent phenomena which are potentially sensorially detectable by any organism, and the existent phenomena which are proven to have caused them. The caveat of potentiality referring to physical, not metaphysical, issues with the mechanics of the sensory processes, because there are known problems with them. That is, instances where sensory detection either cannot be effected, or not completely accurately and/or comprehensively.
In which case, dependence on the sensory processes does not necessitate objective knowledge being limited to validated direct experience. Where there are known functionality issues, what occurred must be hypothesised, but still be based on, and assessment of consequent outcomes referenced to, validated direct experience. That is, objective knowledge of our reality must always be subservient to direct experience, ie either proven to be directly experienceable, or proven to be potentially so.
Essentially, the problem arises when there is a presumption that we can know existence, which we cannot. The confusion being between what, while not directly validatable, is properly inferable from other direct experience, and what is based on no substantiated experienceability.
Re 2: the "not so" referred to the fact that our reality must occur as existential sequence, and that means there is only one physically existent state at a time. That is, for the successor to exist, the predecessor must cease. So the assumption you rejected: 'that systems evolve with respect to an independent time parameter', is true. Or at least is so given the immediate grammatical meaning of the phrase. Frankly, I was not so sure about the others, and hence your view on them, and would need more understanding as to what they are meant to mean.
Re 3: But, as said at 1, this is not what I am saying. In short (again):
Being reliant on these sensory processes limits, it has to be assumed, the form of existence we can know, but not what occurs within that. Because the sensory systems receive, not create, physically existent phenomena in their detectable form (albeit these result from interactions between other existent phenomena, which is what is usually meant by reality), and create information. So the sensory processes can have no influence on our reality, only on information about it.
Re 4: See 2 above concerning sequence, and then:
Change concerns how realities differ, and is therefore not an attribute of any given reality. It is not existent, and neither is the difference. Only physically existent states are existent, it being comparison of these states which reveals difference. Logically, change involves: 1) substance (ie what changed), 2) order (ie the sequence of differences), 3) frequency (ie the rate at which change occurred). The latter being established by comparing numbers of changes occurring over the same duration. This could involve realities in any sequence (including different aspects of the same sequence), and have either occurred concurrently, or otherwise. This is timing.
Re 5: There are no time related assumptions, what is being said is a function of what must be the fundamental nature of our reality (remember, we are trapped in an existential loop). So, to answer one specific question as an example, I do not know what could actually constitute an elementary substance. It is just that, given how our reality is constituted, there must be one, or indeed probably several types. Etc, etc.
On time and timing. The phrase "at a time" refers to occurrence, not time/timing. In respect of the latter: timing compares the number of changes, irrespective of type, in different sequences. This can be done directly, or with respect to a common denominator. So if you are using a quartz watch, it is crystal oscillations. In other words, what is being established is the rate (speed) of a rate (change). And it is all about change, which concerns difference between, not a feature of. There can be no change in whatever constitutes a physically existent state, because otherwise it would involve more than one such state, and physical existence can only occur in one state at a time.
Finally (well I could expand on dimension and space, but have said enough for now!), in respect of: "but I don't think they're simple". You are quite right, but not in the sense you mean. At the generic level, these are precise, when applied, not only is it difficult to discern what, within our reality, they could be, but their simplicity belies their significant consequences. In simple terms, physics has failed to understand the fundamental nature of what it is investigating.
Paul