Robert Lucas in a famous 1978 paper argued that all unemployment was voluntary because involuntary unemployment was a meaningless concept:
“The worker who loses a good job in prosperous time does not volunteer to be in this situation: he has suffered a capital loss. Similarly, the firm which loses an experienced employee in depressed times suffers an undesirable capital loss.
Nevertheless the unemployed worker at any time can always find some job at once, and a firm can always fill a vacancy instantaneously. That neither typically does so by choice is not difficult to understand given the quality of the jobs and the employees which are easiest to find.
Thus there is an involuntary element in all unemployment, in the sense that no one chooses bad luck over good; there is also a voluntary element in all unemployment, in the sense that however miserable one’s current work options, one can always choose to accept them.”
I agree that we all make choices subject to constraints. To say that a choice is involuntary because it is constrained by a scarcity of job-opportunities information is to say that choices are involuntary because there is scarcity. Alchian said there are always plenty of jobs because to suppose the contrary suggests that scarcity has been abolished.
Lucas elaborated further in 1987 in Models of Business Cycles:
A theory that does deal successfully with unemployment needs to address two quite distinct problems. One is the fact that job separations tend to take the form of unilateral decisions – a worker quits, or is laid off or fired – in which negotiations over wage rates play no explicit role.
The second is that workers who lose jobs, for whatever reason, typically pass through a period of unemployment instead of taking temporary work on the ‘spot’ labour market jobs that are readily available in any economy.
Of these, the second seems to me much the more important: it does not ‘explain’ why someone is unemployed to explain why he does not have a job with company X. After all, most employed people do not have jobs with company X either. To explain why people allocate time to a particular activity – like unemployment – we need to know why they prefer it to all other available activities: to say that I am allergic to strawberries does not ‘explain’ why I drink coffee.
Neither of these puzzles is easy to understand within a Walrasian framework, and it would be good to understand both of them better, but I suggest we begin by focusing on the second of the two.