The Slippery Slope

David N. Plank
Stanford Graduate School of Education

Economists draw a useful distinction between two kinds of equity, horizontal and vertical. The principle of horizontal equity holds that equals should be treated equally. For example, third graders in poor school districts should receive the same level of funding and the same quality of education as those in wealthier school districts. All students should be held to the same high expectations regardless of differences in their backgrounds.

The principle of vertical equity holds that unequals should receive differential treatment that responds to their different circumstances and needs. Schools that enroll lots of students from poor and language-minority households should receive additional support to help them meet the educational challenges these students bring to school. Children with disabilities should receive more resources and support than other children, because their needs are greater.

There is an inevitable tension between the claims of vertical and horizontal equity, and no right balance between them. After all, children are alike in many ways and different in many others. Which of the differences among them are sufficiently important to justify differential treatment? And how much differentiation in treatment is justified, or acceptable?

In recent years the principle that we should treat all children alike has effectively trumped the idea that we should treat different children differently. Opponents of tracking and proponents of strict accountability agree: all children should be held to the same high expectations and exposed to the same curriculum.

On the one hand, advocates for poor children note the history of tracking in American public schools to argue that all students should be exposed to a rich curriculum that prepares them for college. (In California, this has produced demands for an A-G curriculum for all students). They assert that opening the door to differential treatment for different students is the first step onto a slippery slope that ends in the revival of tracking, along with reduced expectations and impoverished instruction for poor and minority children.

On the other hand, partisans of strict accountability affirm the principle of horizontal equity to argue that allowing differential treatment for different students allows educators to make excuses for their failure to prepare all of their students for adult success. They assert that treating different students differently will put us on a slippery slope that ends with schools and teachers excusing their own failures by blaming them on students and their families.

Anxiety about stepping onto the slippery slope leads both groups to vehement insistence on the paramount importance of horizontal equity, including uniformly high expectations for students and “no excuses” for educators. This consistency is admirable, if quixotic, but it has brought us to a rhetorical dead end where discussion of alternative policies is effectively prohibited. Proposals that different children be treated differently (see here, for example) are met with the retort that such policies offer “excuses” for schools and teachers that fail to ensure success for all students, or else run the risk of tracking students and condemning poor children to bleak futures.

Fear of sliding down the slippery slope shuts down much potentially fruitful policy conversation, pre-empting consideration of anything other than uniform standards and expectations for all students. Reaffirming the principle of vertical equity and thinking seriously about how to make schools more responsive to the different needs and interests of different students could help enliven an increasingly constricted policy debate, and open up new ways of thinking about how to make schools work better for their students.


Suggested citationPlank, D. N. (2011, June). The slippery slope [Commentary]. Policy Analysis for California Education.