The normally sensible Michael Kinsley gives this analysis of the Supreme Court decisions on affirmative action:

Admission to a prestige institution like the University of Michigan or its law school is what computer types call a “binary” decision. It’s yes or no. You’re in, or you’re out. There is no partial or halfway admission. The effect of any factor in that decision is also binary. It either changes the result or it doesn’t. It makes all the difference, or it makes none at all. Those are the only possibilities.

For any individual, the process of turning factors into that yes-or-no decision doesn’t matter. Any factor that changes the result has the same impact as if it were an absolute quota of one. It gets you in, or it keeps you out. And this is either right or it is wrong. The process of turning factors into a result doesn’t matter here, either. In this sense, the moral question is binary, too.

This isn’t right. Doesn’t Kinsley know the difference between necessary and sufficient conditions? He’s writing as though race (and everything else) were both necessary and sufficient—either it makes all the differene or none at all. Last time I looked, though, being a member of a racial minority group wasn’t sufficient to get you admitted to Michigan Law. It wasn’t necessary either, as a glance at most of the law students there will tell you. Of course, minority status can raise your chances of admission, in conjunction with other conditions, and may sometimes be an added variable that pushes a candidate into the ‘Yes’ pile. That’s the whole point of affirmative action. But it’s wrong to argue, as Kinsley does, that “’no role’ and ‘determinative factor’ are in fact the only possible options” and that “There cannot be an infinite variety of effects on a yes-or-no question.” Actually, there can. Either you’re married or you’re not married. Yet there are an enormous number of causal paths to this simple binary outcome.

There is a subtler point here that depends on whether you are looking at things from the point of view of the admissions officer or the point of view of the individual applicant. The admissions officer cares about the overall composition and characteristics of the whole class. Each applicant just cares about whether they get admitted. If Michigan mechanically applied a formula to each applicant, then one’s particular characteristics might directly determine admission or rejection, from your point of view. From the admissions officer’s point of view, though, any particular characteristic would make a quantifiable but not determining difference. Perhaps this is what Kinsley is trying to get at.

Update: Dan Drezner makes the same initial point about necessity and sufficiency.