Ilya has been doing some recent blogging about tenure, and I thought I would flag what seems to me the most persuasive argument in its favor: Academics are the best judges of who is a good academic, and tenure is necessary to ensure that a group of academics will hire the best person to fill an open faculty slot. This argument is made in detail in H. Lorne Carmichael, Incentives in Academics: Why Is There Tenure?, 96 Journal of Political Economy 453 (1988). The basic idea is that tenure is a necessary evil because faculties vote on who to let join them: If professors know that their own jobs will be in jeopardy if they hire someone better than themselves, they will make sure that they only hire incompetent new people.
Maybe everyone else is familiar with this argument, but I hadn’t seen it until recently: It turned me from a tenure skeptic to a modest supporter.