This criterion means that each intelligence can be articulated and communicated through some form of symbolic system. For example, linguistic intelligence is expressed through language, musical intelligence through musical notation, and logical-mathematical intelligence through mathematical symbols. The ability to encode these intelligences in symbolic forms allows for communication, teaching, and further development of these skills. It underscores the human capacity to abstractly represent and transmit complex cognitive abilities, making them accessible and teachable. This aspect is key to understanding how different intelligences are manifested and utilized in cultural and educational contexts.

This criterion posits that each type of intelligence must have a core set of cognitive processes or operations. For example, linguistic intelligence involves operations like the ability to use language for expression and comprehension, while logical-mathematical intelligence includes the capacity for deductive reasoning and problem-solving with numbers. The distinct operations characterize each intelligence, making them identifiable and unique. This aspect is crucial as it provides a concrete basis for differentiating between the various intelligences, emphasizing that each is not just a skill but a distinct cognitive domain.

The criterion "Potential Isolation by Brain Damage" refers to the notion that distinct intelligences can be independently affected by brain damage. This means that a specific type of intelligence can be impaired or lost while others remain intact, indicating its unique neurological basis. For instance, a person might suffer damage to a part of the brain responsible for linguistic abilities, losing their capacity to use language, while their mathematical or musical abilities remain unaffected. This criterion supports Gardner's idea that multiple intelligences are separate from each other, each residing in different areas of the brain.

Criterion of evolutionary history and plausibility suggests that each intelligence has evolved to solve specific problems faced by our ancestors. For example, spatial intelligence helped in navigation and understanding the physical environment, while interpersonal intelligence was crucial for social communication and cooperation. This evolutionary perspective implies that these intelligences are rooted in human survival and adaptation needs. It gives the theory an evolutionary framework, suggesting that these intelligences are not arbitrary but have developed in response to real-world demands.