About 30 percent of faculty members are either tenured or on the tenure track, compared with about 57 percent in 1975. The rest are “contingent faculty”: About 19 percent work full time, usually on contracts lasting one to three years, and more than half work part time. (These figures omit graduate students who also teach classes.) Along with a lack of job security, contingent faculty members receive lower pay and fewer, or no, benefits. They frequently don’t have offices and may not even get library cards.
Why the change? Tenure makes it very difficult for academia to respond, and adapt to a changing external environment. And there are few industries changing as rapidly as academia (see past posts: Failing to Educate, How should universities respond to rising costs, declining demand, and the emergence of cheap alternatives?, Making Research more Relevant, Irony: do business schools practice what they preach?, Incentive pay for professors, Agents vs. principals: the strange case of Dartmouth, Dartmouth governance, again).
Competition favors lower cost organizational forms, so it is not surprising that we see a decline in its use.