His major contributions were the Cattell-Horn Theory of Fluid and Crystallized Intelligences, the application of advanced statistical techniques to the study of intelligence and an author or co-author of more than 500 books and articles. Specifically, the Cattell-Horn theory of fluid and crystallized intelligence proposes that general intelligence is actually a collection of perhaps 100 abilities working together in various ways in different people to bring out different intelligences. Cattell held a hereditarian view of intelligence, arguing that the weight of the statistical evidence supports the idea that intelligence is largely determined by genetics. ...