A large factor involved in the differences among the various theories concerning the nature of intelligence surrounds the definition of intelligence. As you will see, many of the differences stem from the fact that the word intelligence is defined in different ways. Some theorists include the whole range of talents, while others include only certain abilities. Some think that people are born with a specific capacity, while others believe one's intelligence develops as a result of his environment. Yet others prefer to consider the differences between acumen, or agility of mind, and the actual learning of material.
Many people have some views about intelligence, such as being smart, talented, or hard working.
However, many agree that intelligence is the capacity to acquire and use knowledge. Intelligence is not actually what a person knows, but the potential for acquiring and using knowledge. One's potential for obtaining and applying knowledge is impossible to measure directly, and must be measured by indirect means. The results of these knowledge tests are then compared to others with a similar characteristic, usually age, and the intelligence is thus estimated. IQ tests do just this, measuring intelligence through the amount of knowledge a person has.