It is strange to pretend to be a democracy, and then give power to long dead men to decide what the rules are, offering a veto to a handful of unelected people to "interpret" what those men decided long ago.

A democracy should make its own rules as it goes. Americans living today ought to decide the rules under which those Americans live, not hope that somehow slavers who lived centuries ago magically determined the correct rules to live by forever.

I don't think writing some of the rules down in bigger type and calling those a "Constitution" helps much at all, and so I'd argue against it as a practice, but certainly a situation in which most Americans weren't born until after the constitutional rules in place today were fixed is not a success. The last successful new Constitutional Amendment to be written was in 1971. If you were born after 1971 your "democracy" never really decided any of these rules, if you were born after 1950 you never voted for the rules you live under.

In its early days the American Republic fiddled with the Constitution a great deal, and that's much less objectionable. Even as late as a century ago, there was some flexibility left in this vital joint, but today it's gone.

Constitutions are usually written after major crises in a period of national unity supposedly with large if not universal consensus. The idea is that a simple majority is not enough to change them.

Not everybody agrees, for example in UK the parliament is the ultimate sovereign and it is not bound by law other than self restraint.

Parliament offers the ultimate demonstration of how you know who is really in charge. King Charles kept starting wars, the Parliament told him to stop, he didn't and so they executed the King. That's a sovereign entity.

While requiring more than "a simple majority" seems like a mechanism to prevent certain regrettable outcomes, it really doesn't, it's just a line in the sand. We should oppose a million people voting to execute one innocent just as fervently as 500 people voting to execute 499 innocents, the problem isn't the ratio and so a correct solution can't be about the ratio.

Consensus is great, I love consensus - if you can find a consensus that's brilliant. But super-majorities are not a consensus. And of course when you really do have a consensus it tends to be naturally enduring anyway. I am very dubious of people who imagine that there might be a consensus for policy one minute and then shortly after the consensus is gone. I think there was only ever some clever sleight of hand to deliver the illusion of consensus at all for some purpose.

I don’t think the argument is that super-majority is consensus, but that it’s self-evidently closer to consensus than a simple majority is.

When contemplating making major changes in governmental structure, consensus would be best, but super majority is probably second-best and first-achievable.

You can’t run a country needing 100% consensus of over 200M people.