This post is a response to a defense of diversity hiring that I've often heard repeated by supporters of such practices, namely "Yeah sure, SOME women are given jobs over men just to meet diversity targets, but MOST of the women in any given job are just as qualified as the men and would be there even without diversity hiring. Diversity hiring only operates on the margin."

Under a few simplifying, straightforward assumptions, this is shown to be entirely false. Of course in the real world nothing is so straightforward and there are obviously frictions in the job market, but I think this is a useful model for thinking about this problem.

Assumption 1) Jobs (at least within a field) can be ranked objectively in terms of desirability, and all workers seek out the most desirable job they can obtain.

Assumption 2) Employees (once again, within a field/area of specialization what-have-you) can be ranked objectively in terms of ability and all employers seek out the most able employees they can obtain.

From these assumptions it's easy to show who ends up with what job. The most able worker gets the most desirable job, the second-most able worker gets the second-most desirable job and so on.

Now let's modify this model with:

Assumption 3) Women are considered diversity hires at all levels of the field, and points are added to an employee's objective "ability score" if they help to satisfy diversity goals.

Now let's examine a counterfactual. Say that a woman was working at a job and WASN'T a diversity hire. Then, given her ability, she could get a better job at a place where she WAS a diversity hire. Under the assumptions above, she would do so and all women would be diversity hires.

TL;DR