One reason to use IQ testing is, in fact, the exact reason why it was created. The first IQ test, designed by psychologist Alfred Binet of France, was designed to assess differences between "intellectually normal" students and those who had a lower intellectual capacity. The intent of this differentiation was to identify children who would benefit from specialized education, similar to what we refer to today as having "learning disabilities." In instances when IQ testing is faithful to the original purpose, there is still a benefit to using IQ testing as a basis for programs to assist students who need special education.
Another argument in favor of IQ testing is similar, but the converse of identifying learning disabled students. Clearly, an IQ test that identifies below-par performers is also likely to identify above-par performers. Some adult genius-level individuals will state that their genius-level intelligence was first identified on standardized grade-school IQ tests. Because these children also can benefit from special education programs, it makes a compelling argument for IQ testing.
One argument against IQ tests is that no one has really been able to define, with reference to any such test, what is meant by the word "intelligence." How can we quantify something when we do not know what it is that we are attempting to measure? Because children can get saddled with labels based on the scores of IQ tests, which in turn can affect their future performance, this factor is a strong case for reconsidering the value of standardized IQ testing in childhood.
On a variety of criteria, IQ testing has exhibited bias. Different IQ tests administered to the same individual can demonstrate serious discrepancies in the ratings. Further, the biases of the testers themselves have an effect on outcomes. Indeed, one study indicated that a control group of university students limited to those with no more than an introductory course in education or psychology had an accuracy rate 25 percent greater in making learning disability assessments based on test scores than did school psychologists and special education teachers. This same study indicated that the maximum accuracy rate for the so-called professionals in the field was only that of correctly identifying the learning disabled at a 50 percent accuracy rate. In other words, the professionals were wrong half of the time. The reality that entire generations of children can potentially get labeled as learning disabled based upon the assessments of people who are wrong as often as they are right is a definite argument for eliminating IQ testing.
A particularly frightening reason against IQ testing is the fear that developers of IQ testing will design tests with the specific purpose of identifying sub-par individuals for the purpose of eradication of the bloodlines. On this principle, IQ tests have in the past been used in some states as a basis of administering enforced sterilization. As with any discriminatory practice such as this, the fact that it has once been used in such a manner means that it is entirely possible for it to happen again in the future.