"..this is a legal premise that has existed for over a century. Otherwise, you couldn't sue a company for damages."
The way our particular laws have been written and interpreted by the Supreme Court, then yes, these things are indeed tied together. But there's no particular reason why one could not have a legal system with one and not the other. That's the entire point of the OP.
Why exactly is unrestricted freedom of speech a necessary condition for corporate immunity? Assume you are building a constitution from scratch: Can you construct an argument for why you can't have corporate immunity without corporate freedom of speech, without referring to existing US case law?
"But there's no particular reason why one could not have a legal system with one and not the other."
Yes, but if it's a matter of "a corporation should have some rights a human has, but not other rights", we're already there. The idea that corporation has all human rights is already transparently false. For one thing, anything that requires a "citizen" is going to be something they can't do.
Anyone who thinks that we've transitioned from "corporations have some of the rights of humans" to "corporations have all of the rights of humans" is emoting, not thinking. We've gone from one subset of rights, to another, to yet a third.
And they still have responsibilities, and in fact have some responsibilities that normal citizens don't have. The casual presumption, for those that are so presuming, that this particular transition is some sort of unique disaster or major shift in the balance of rights v. responsibilities is not justified.
The OP is making a (toungue-in-cheek) argument against corporate free speech. You said that corporate free speech rests upon a century of precedent and that without it, we couldn't have corporate immunity.
But "corporate immunity and corporate free speech come from the same legal doctrine" is a lot different from saying "you can't have corporate immunity without corporate free speech". The latter is what you said, but your argument supports the former. Are you sure I'm the one who is confused?
Well, I think that's far and away the most obvious interpretation of your second paragraph, but it's ambiguous enough that I'll give you the benefit of the doubt if you're saying that's not what you meant.
Your last sentence surprised me, though. Clean-slate thought experiments are useful to figure out whether you're doing something because it's the best way to do it, or just because of legacy. That goes for both code and law.
In particular, some of the other critics of the Citizens United decision, including ones who are a little more serious and a little less playful than the OP, are talking about a long-term campaign for a constitutional amendment to address this issue (I'm in particular talking about Larry Lessig and Change Congress, but there are others). Such efforts might be political longshots, but how do you engage in discussions with them if you don't want to consider all the ways the law could be radically different, or could have evolved entirely differently?
Human political freedom in the US is something I'm interested in, and I'm not actually interested in wandering off the topic. I would hope someone engaging me in discussion on the issue wouldn't try to pull off into other directions - that would be disengaging.
The way our particular laws have been written and interpreted by the Supreme Court, then yes, these things are indeed tied together. But there's no particular reason why one could not have a legal system with one and not the other. That's the entire point of the OP.
Why exactly is unrestricted freedom of speech a necessary condition for corporate immunity? Assume you are building a constitution from scratch: Can you construct an argument for why you can't have corporate immunity without corporate freedom of speech, without referring to existing US case law?