Recently a colleague in a STEM field was describing the difficulty of finding qualified experts to teach a particular upper-level course, and it never occurred to me to ask, "Can't anyone in your department teach that?" I've been around academe long enough to know that every field has its areas of expertise and while most of us could, in a pinch, teach an intro-level course outside that area, those upper-level specialized courses require a level of expertise not possessed by everyone.
So it's always surprising to be reminded that others don't necessarily share that understanding. Years ago we had a provost who wanted us to search for someone who could teach anything, but good luck finding that universally qualified person. Maybe it's a mistake for graduate programs to insist on turning out scholars with expertise in specific areas, but on the other hand, how long would you have to stay in grad school to become an expert in everything?
And now that my own department is working on ways to staff certain courses in the coming years, I'm hearing that same annoying question that I've refused to ask others: "Can't anyone in your department teach that course?"
The problem is that anyone doesn't work here. Instead, we are an eclectic collection of someones who have worked long and hard to develop expertise in specific areas, and while we're all committed to lifelong learning and willing to stretch outside our comfort zones, it would be ridiculous to expect any of us to develop full-blown scholarly expertise in an entirely different area in our "free time."
Maybe somewhere there's an academic discipline in which anyone can teach everything, but until that condition becomes universal, we'll continue to rely upon that highly qualified someone to teach that special something so necessary to our students.