We have been engaged in decades-long public policy debates on gaps and how best to close them: the income gap, the student achievement gap, gender-linked gaps in employment opportunities. But why do we care so much about gaps? In a land of diversity, why are subgroup differences such a concern?
At a basic level, we care about gaps because (or when) our fundamental assumption is that, on a “level playing field," there should be no systematic differences among people based on ascribed traits, such as race and gender, that are unrelated to the “game." It is “ok” if a specific Hispanic kid performs at a lower level than his/her white counterpart or vice-versa. But it’s not ok if, on average, Hispanic students’ test scores systematically lag behind that of similar white children. Why? Because we know intelligence and ability are normally distributed across racial/ethnic groups. So, when groups differ in important outcomes, we know that this "distance” is indicative of other problems.
What problems exactly? That is a more complex question.