Nor is the plan a form of affirmative action. Affirmative-action admission policies — like those in place at some universities — require that race be one part of a host of measures considered. Mr. de Blasio’s plan doesn’t stipulate any racial criterion for admission, much less racial quotas (which the Supreme Court outlawed in 1978). The plan will simply give kids from a wider variety of backgrounds access to a public resource: an excellent public high school education. This is a public resource, something all New York City families contribute to with their taxes. Only about 5 percent of all New York City high school students are enrolled in a specialized high school and last year half of these kids came from just 21 middle schools.

That means that only five percent of kids are getting access to a valuable public resource. Frankly, Mr. de Blasio’s plan doesn’t fix this problem of inequality. Under his plan, even though the elite high schools would get a bigger range of students, the number of children getting access to this public resource will remain about the same — minuscule.

This is what critics of the plan should be outraged about. All kids deserve a top-rate education in schools with qualified teachers and ample support staff and a wealth of curriculum materials and supplies. All of our schools should be elite schools.

To be against Mr. de Blasio’s proposal is to be against a very limited attempt at giving more kids access to a limited resource. His plan doesn’t add more seats. It just allows more kids a shot at one of those seats — kids whose families can’t afford years of test prep classes and tutors, who live in under-resourced districts, and yet who still manage to excel in their own schools.

City Councilman Peter Koo has said, “The test is the most unbiased way to get into a school.” He’s wrong. Researchers have long found evidence that test scores can underestimate the abilities of minority students who are confronted with negative stereotypes about their own ethnic group. Beyond that, for school admissions to be truly unbiased, all students would need to have equal access to elementary schools and middle schools that receive equal shares of property taxes and state and federal aid and have the same cultural, educational and social resources.