Mainly this:
https://en.wikipedia.org/wiki/Basic_norm
Hanover and I have a long-standing disagreement about whether, for instance, international law is law or not.
And I disagree that all definitions are arbitrary. If we are attempting to describe reality, in this case a sociological phenomena like law, just making stuff up doesn't really cut it. Just including a "procedural requirement" in the definition of law doesn't resolve much. Is this procedural law a law? Yes, it was done by procedure. Until you end up with the first law, which wasn't established by procedure and we have to conclude it isn't law, subsequently invalidating all laws deriving from it.
It also ignores the role of customary law. When a judge applies a rule based on custom, the judgment recognises a certain custom as law but it was law before the judge recognised it as such otherwise he would not have had an obligation to apply it in his judgment.
I agree generally with what you said, but I think you underestimate the significance of bargaining power and that complex interactions involve complex agreements that go far beyond the four corners of a contract, especially when that contract is a highly complex and politically sensitive issue like a treaty.
Consider your father told you that if you do the wash, he'll pay you $10. You do the wash, but he doesn't pay. Next week he asks you to do the wash, you protest over your outstanding debt, and then he explains how your debt to him is far greater than his to you and that the repercussions of your not doing the wash will far outweigh the relief of not having to do that wash. And so what do you do? You do the wash. — Hanover
Is this still a contract though? Or has it become an order? Or is it a promise made under duress? That's not to say
orders can't form the basis of laws but I generally consider treaties the exchange of promises. A treaty established under duress (treaty of Versailles?) doesn't seem like an actual promise, just as me promising a mugger to "empty my pockets" isn't much of a promise either.
While it is true I spent very little time on bargaining power, which might give the impression I think little of it, I didn't really deal with it because I didn't think it's relevant for this question. The reason I don't think it fundamentally changes what I said is because where bargaining power is successfully exercised, it
skews the results of what one party gets out of it as opposed to the other party. So the promises exchanged are more favourable for one party than the other. However, I don't think it fundamentally affects the underlying rule that promises ought to be kept because this is implied in a promise.
I'll certainly accept that there will be grey areas where duress, orders and promises cannot be clearly distinguished. And I think it's making me realise my idea of law is incomplete because where it concerns contracts and treaties, the basis is cooperative when promises are exchanged freely and only if done freely can we reasonably derive implicit rules from such acts. Orders can be given based on powers freely transferred at some earlier time and if those orders move to far away from what a population in general would agree to if they were free to negotiate terms themselves, I guess we get bad law.
But back to treaties. In my view, a way of accepting breaking treaties "for convenience", is arguing that promises made by governments (legal entities with legal personality) are fundamentally different from promises people make but that seems inconsistent with the fact that trust in government (by its citizens and, by extension, validly existing legal entities) is based on the government keeping its word. The only thing that really changes is to whom the promises are made, which in this case is another government. I don't see how the nature of the recipient of the promise, changes the nature of a promise itself though.
I'm also wondering how you see the Supremacy Clause in relation to a ratified UN Charter. What status do you think the rules of the UN Charter have in the US legal system, if any, taking into consideration the Supremacy Clause, and why?
EDIT: I realise I didn't reply to all your points. Sorry, time constraints and I don't want to put off answering for too long as that tends to kill discussions.