(This post started out as a comment on Niq's blog post regarding changing the rules of succession to the throne of the UK. Niq sees it as a modernist plot aimed at undermining the monarchy itself. I disagree.)
I'm wary of commenting on royalty. The medieval doctrine of the King's Two Persons has been updated, in our time, as a dichotomy between the royals' role as National Figureheads and their role as Mildly Irritating Celebrities. No matter how elevated you try to be, it's hard to prevent the discourse from degenerating into How Wonderful Her Majesty Is and whether Charles Should Stand Aside And Let Wills Take Over After She's Gone, which is a subject that interests me marginally less than the salt content of frozen peas.
But behind the soap opera there is a dark magic at work here, one that medieval philosophers understood far better than modern journalists, for all that they never knew whom their king was boffing on the side.
Niq believes that the "defining characteristic" of a monarch was to be a military leader. I think that role was only ever peripheral. It fell into disuse when the army became professional, for two reasons. First, the more reflective type of soldier began to think that it might be better (from the participant's point of view) for battles to be directed by people who had studied the subject full-time, rather than by some playboy in a funny hat.
The second, and more important, reason was that with a professional army, you no longer needed the king to raise his standard in order to signal to the peasants that it was time to down tools and come to fight. And that is our clue to what kings are really for.
A monarch's most basic job is to be recognised. No matter what our disagreements, on topics ranging from eugenics to spinach recipes, we all owe allegiance to the same monarch (which is how we know we're British). And once she announces what our national policy is - re, for example, Libya - that's what the country will do (us included), whether we personally agree with it or not.
(Of course a constitutional monarch doesn't make announcements like that in person, but through her officers in government and/or parliament. But that's a minor distinction.)
So: does changing the law of succession weaken the monarchy as an institution?
On the face of it - no. That's why there had to be a meeting of Commonwealth heads of government, and they agreed to the change unanimously. If just one country had opposed it - or even abstained - then there'd be the real prospect of a split monarchy, and that really would mean the end of monarchy as a useful institution. But they all approved it, so that particular crisis was averted.
If there is a danger here, it's the "can-o'-worms" type: the danger that by drawing attention to the subject, you will encourage people who want to make other, further-reaching changes.
But in truth, they didn't need encouragement.
Speaking from one of the loyaller Colonies, I can assure you that the "Monarchy vs Republic" debate is never far below the surface, particularly during a news drought. Any columnist in New Zealand, faced with a looming deadline and no imagination - which is to say, most of the time - won't hesitate to reach into their bag of pre-mulled opinions and reheat some tired old diatribe about either Shaking Off The Legacy Of Imperialism or Maintaining The Roots Of The Nation.
If anything, I think that changing the rules as a concession to modern ideas of "fairness" will make the monarchy more robust. It reinforces the idea of a living institution, whose rules can change. And it reminds us all that, when all is said and done, the queen is queen not because of who her parents were, but because we say she is.
"Divine right" died with Charles I, and good riddance to it.