On Twitter, Bryan Caplan asks me to clarify why zero marginal product workers do not clash with the notion of comparative advantage. The point is simple: some workers destroy a lot of morale in the workplace and so the employer doesn’t want them around at any price.
Most of us buy into “morale costs” as a key reason behind sticky nominal wages. If your wage is too low, your morale falls, you produce less and so the wage cut isn’t worth it. Well, what else besides low wages makes people unhappy in their workplace? Very often the quality of co-workers is a major source of unhappiness; just listen to people complain about their jobs and write down how many times they are mentioning co-workers and bosses. (I do not exempt academics here.) A “rotten apple” can make many people less productive, and you can think of that as a simple extension of sticky nominal wage theory, namely that installing or tolerating a “pain in the ass” is another way of cutting wages for the good workers, they don’t like it, it lowers their productivity, and thus it is not worth tolerating the rotten apple if said apple can be identified and dismissed.
There is no particular reason to think that ZMP workers are especially stupid or in some way “disabled.” If anything it may require some special “skills” to get under people’s skins so much. (Of course there are some individuals who, say for health reasons, cannot produce anything at all but they are not usually in or “near” the active labor force.) To draw a simple analogy, the lowest-publishing members of academic departments are rarely those who make the most trouble.
To the extent production becomes more complex and more profitable, ZMP workers are more of a problem because there is more value they can destroy. The relevance of these morale costs also varies cyclically, in standard fashion. A company is more likely to tolerate a “pain” in boom times when the labor itself has a higher return.
Note also the “expected ZMP worker.” Let’s say that some ZMPers destroy a lot of value (that makes them NMPers). You pay 40k a year and you end up with a worker who destroys 80k a year, so the firm is out 120k net. Bosses really want to avoid these employees. Furthermore let’s say that a plague of these destructive workers hangs out in the pool of the long-term unemployed, but they constitute only 1/3 of that pool, though they cannot easily be distinguished at the interview stage. 1/3 a chance of getting a minus 120k return will scare a lot of employers away from the entire pool. The employers are behaving rationally, yet it can be said that “there is nothing wrong with most of the long-term unemployed.” And still they can’t get jobs and still nominally eroding the level of wages won’t help them.
In the perceived, statistical, expected value sense, the lot of these workers is that of ZMPers.
One policy implication is that it should become legally easier to offer a very negative recommendation for a former employee. That makes it easier to break the pooling equilibrium. There also are equilibria where it makes sense to “buy the NMPers out” of workforce participation altogether, pay them to emigrate, etc., although such policies may be difficult to implement. Oddly, if work disincentives target just the right group of people — the NMPers — (again, hard to do, but worth considering the logic of the argument) those disincentives can raise the employment/population ratio, at least in theory.
Addendum: Garett Jones offers yet a differing option for understanding ZMP theories.