What theory states that intelligence is not a single concept but is composed of a minimum of eight different intelligences, each relatively independent of the others?

The theory that states intelligence is not a single concept but is composed of a minimum of eight different intelligences is Howard Gardner's "Theory of Multiple Intelligences." According to Gardner, each person has a unique combination of different types of intelligence. These intelligences work together in complex ways, and traditional IQ tests that measure only linguistic and logical-mathematical abilities do not capture the full range of human capabilities. The original eight intelligences proposed by Gardner are:

1. Linguistic Intelligence: The ability to use language effectively, both in terms of speaking and writing. 2. Logical-Mathematical Intelligence: The capacity for inductive and deductive thinking and reasoning, as well as the use of numbers and abstract pattern recognition. 3. Spatial Intelligence: The ability to visualize with the mind’s eye, as an artist or architect might. 4. Musical Intelligence: The ability to perform, compose, and appreciate musical patterns, including rhythm and pitch. 5. Bodily-Kinesthetic Intelligence: The capacity to manipulate objects skillfully and to use physical skills such as dance or athletics. 6. Interpersonal Intelligence: The ability to understand and interact effectively with others. 7. Intrapersonal Intelligence: The ability to understand oneself and one's thoughts and feelings. 8. Naturalistic Intelligence: The ability to make distinctions in the natural world and to use this ability productively, such as in farming or biology.

Gardner later suggested the possibility of a ninth intelligence termed "Existential Intelligence," which is the capacity to tackle deep questions about human existence.