One thing though that is a bit hard to explain, and I would like to hear your thoughts/understanding on this.
Establishing causation includes at least establishing precedence in addition to correlation. In other words, the very definition of time is intertwined with the relationship between causes and effects. And Physics does not yet claim to have understood what time means (AFAIK): It is really real? Is it something just within our heads? ...
If you do not treat causation as a fundamental notion, do you treat time as one? If yes, how do you explain the dependence between the two. If not, well, that becomes a subject of even more basic discussion since then I would ask what do you treat to be fundamental notions. :-) (There does not seem to be a way for us to get around fundamental notions completely.)
When I studied physics as an undergrad, I was made to take a course in experimental particle physics (in Germany they call this "Phenomenology", not in English to my knowledge). I complained that I wanted to study the fundamental laws of physics, not how they were tested. They university advisor replied that in order to understand how the world works, first we have to know what it looks like.
This is basically my view on this matter. We can only take for granted the existence of the objective universe. Everything else must be derived from experiment, including concepts that seem fundamental like time or causality.
One interesting thing about causality is that the fact that the macroscopic world obeys cause-and-effect laws is usually attributed to the second law of thermodynamics. But where does the second law of thermodynamics come from? I've heard it stated (can't say if this is universally held by physicists) that the second law of thermodynamics holds because the initial state of the universe had very low entropy, while the final state of the universe will have very high entropy. That is the second law of thermodynamics is "caused" by both the initial and final states of the universe. So causality and time are something that we don't fully understand yet.
Establishing causation includes at least establishing precedence in addition to correlation. In other words, the very definition of time is intertwined with the relationship between causes and effects. And Physics does not yet claim to have understood what time means (AFAIK): It is really real? Is it something just within our heads? ...
If you do not treat causation as a fundamental notion, do you treat time as one? If yes, how do you explain the dependence between the two. If not, well, that becomes a subject of even more basic discussion since then I would ask what do you treat to be fundamental notions. :-) (There does not seem to be a way for us to get around fundamental notions completely.)