In engineering, at least, adjuncts often are teaching in their free time and working a full-time engineering job. They do it because they enjoy the teaching, or

In engineering, at least, adjuncts often are teaching in their free time and working a full-time engineering job. They do it because they enjoy the teaching, or because in a few cases they appreciate the extra money. Several of my colleagues do that; my office is next to the guy who teaches advanced undergraduate and graduate level astrodynamics at the local state university. But he is working full time as a civil servant and pulling that salary, plus the adjunct pay on top of it. You can get away with paying those adjuncts a pretty low wage. But then it drives the cost of adjuncts down across the board. The problem really comes in when you are in a field that doesn't afford you full-time non-academic employment, such as the arts or sciences such as archaeology etc. and are teaching full time to pay the bills (or not, as the case may be).