This, presumably, is a pro-minimum wage cartoon. This, clearly, is an anti-minimum wage column. But putting our economist’s hat on for a second — aren’t they making the same argument?
This has bugged me about the minimum wage debates for a while. Supporters say, mandating higher wages will lead to more motivated employees, less turnover and training costs, less need for supervision. Opponents say, mandating higher wages will lead to mechanization of jobs currently done by low-wage labor, substitution of capital for labor. But at an abstract level, it seems to me these are just two ways of describing the same thing. Aren’t they both just saying, faster growth of labor productivity? How can the same predicted outcome be an argument both for and against higher wages?
The anti- side seems to be implicitly assuming a fixed quantity of output, so that less labor per unit means less labor overall. The pro- side seems to be implicitly assuming some combination of a flat demand curve and a flattish supply curve, so that a fall in costs leads to a large rise in output. But you’ll still get some fall in employment, in the absence of monopsony or demand effects.
Anyway my interest here is not in what is the right answer.  My interest is that supporters of a higher minimum wage invoke efficiency wage arguments without explaining why that should be expected to dampen disemployment effects rather than amplify them. While opponents of higher minimum wages describe faster productivity growth as a cost, without, as far as I can tell, being against it in any other context. This is a case where abstraction — some equations, even one of those awful supply and demand graphs — might actually be helpful.
 Just to be clear, I support a higher minimum wage, $15, whatever. A few years ago, I even testified to that effect before the Maryland state legislature.