I’m an adjunct right now as well, and I don’t think it is unfair to say that reliance on adjuncts can lead to a decline in quality. That isn’t because adjuncts aren’t quality professors, but because of the circumstances we are working under:
- I have 50 students between my two sections of freshman writing this semester. Since I'm making under 5000 per section, I also have to teach elsewhere to make a reasonable living. That leaves me with less time than I would like to spend on my freshman writing classes -- it isn't feasible, for instance, for me to read full first drafts of each essay, as I did when I used to TA for two sections of 15 students.
- I am simply not on campus enough to meet with students as much as I would like to. I can offer to meet with them before and after class, but in an ideal world, I'd be having mandatory conferences as part of the course.
- While there are certainly some long-term adjuncts like sylvan, relying heavily on adjuncts means a lot of turnover -- and a lot of fairly new teachers teaching courses for the first time. I think I've done a good job this year, but if I teach the same courses next year, I know I'll be more effective simply because I've learned from my experience. Obviously, everyone has to have a first time teaching a class -- but in a school with more full-time faculty, you're likely to have a larger proportion of courses taught by experienced people, many of whom have been teaching the same course for some time.
- There is such a glut of under-employed PhDs that most adjuncts are highly qualified, but good teaching isn't a universal skill, and if you're hiring a revolving door of part-timers, you're simply not going to maintain the same kind of quality-control that you would if you were mainly hiring to fill a few long-term positions each year. It is true that hiring and tenure decisions have more to do with research than with teaching in most cases, but every tenure-track job I've heard of has required a teaching demo as part of the process, often along with a statement of teaching philosophy and/or other "evidence of teaching excellence." I got hired at the school I adjunct at on the basis of a cover letter and a cursory meeting with the chair.