The future which we hold in trust for our own children will be shaped by our fairness to other people's children. -- Marian Wright EdelmanMost people try to do what they are aiming for at the minimal cost to their own energies and resources. To expend time and energy pointlessly is thought to be inefficient, certainly no virtue.
Teachers -- though they dislike the simile -- are like battlefield surgeons. They have limited supplies, time, and energy, and demands greater than they can handle. Thus, if they want to be efficient, they divide their potential patients into three groups:
1) the Gifted: those they can neglect because they will get well (learn) anyway -- they don't need it, whereas others do;
2) the Subnormal: those they should neglect because all (or an unfair proportion) of their resources will not help anyway, the resources available are insufficient to help them and would be wasted;
3) the Normal: the group that will show maximum improvement (learning) for the resources used. Allotting resources to this group optimizes their effect.
This is called triage in medicine. In education it is called teaching to the middle. A common Principle of Equity, Fair Share, requires that no one receive more of a scarce resource than any other -- all things being equal.
Special education identifies both the Gifted and the Subnormal as Special Students, exempting them not only from the particular rules that support triage, but also from the Fair Share principle. This invariably shortchanges the normal student.
Should we give up on efficiency? When resources are scarce, which kids should we deprive?
To examine these issues further, see, The Ethics of Educational Triage