Never?

It’s a balancing act with no clear one size answer. Can’t fix stupid, nor can you teach wisdom. There’s definitely situations where I’d want someone older in charge, cooler heads and all that.

I think when you see a rigid seniority system in place, it’s usually a stand in for a more equitable solution. Sometimes the argument over who gets precedent isn’t worth the trouble, and it’s easier to just say fuck it and go by seniority. Less fair than some methods, fairer than a lot though too.

Merit is generally the superior of the two. Seniority should only really be preferred if:

• The performance of the task at hand is more dependent on pre-established connections and the like - ie a very knowledgeable and charismatic but new diplomat might actually be a worse choice for a given job than a rather boring and mid-tier diplomat who nonetheless has a lot of long-standing relationships in the area.

• There is an issue of systemic rules in an institution where merit is not always the top concern, or not easily and clearly discerned - such as legislative committee appointments. “The best person is the most qualified for the top job” is a nice thought, but raises questions of “How do you figure out who is the best person?” and “The people didn’t send the best person, they sent this fellow to represent their interests.”