General cognitive ability is the degree to which a person is able to learn. The difference between cognitive ability and intelligence is the genetic potential and the concept of developing. Even though cognitive ability is influenced by genes, it is influenced by much more than only the genetic potential. Cognitive abilities that are narrower than general cognitive abilities are called specific aptitudes, and they used to use these aptitude measures as better predictors of job performance rather than General Cognitive Ability. But recent research has shown that General Cognitive Ability is the best prediction of job performance, whereas aptitudes have no contributions to that prediction, because of the higher degree of validation.

Empirical research have shown that there is a strong link between General Cognitive Ability and job performance, which is so strong, that General Cognitive Ability can be considered as a valid predictor of job performance. It would be curious if General Cognitive Ability would not be a valid predictor of job performance, since General Cognitive Ability is used as a predictor for many aspects of human lives, such as income, education and criminal behavior.

The reason why General Cognitive Ability is so important by predicting job performance is because people higher in General Cognitive Ability acquire more job knowledge and they acquire it faster. When knowledge of a job is higher, this automatically leads to a higher level of job performance. According to Schmidt, it would be better if General Cognitive Ability was less important, and when specific aptitudes would be better argued and used by selecting and prediction job performance. But because of the large amount of evidence, Schmidt has to admit that General Cognitive Ability is too important to neglect.

Social Policies are striving for equal representation of all groups in all jobs at all different levels of job complexity. But every group differs in General Cognitive Ability and therefore in job-relevant skills and abilities. And because Social Policies should encourage managers to hire employees on basis of performance predictors such as General Cognitive Ability, it is not realistic to strive for this equal representation.