Isolation as a Brain Function
As medicine studies isolated brain functions through cases of brain injury and degenerative disease, we are able to identify actual physiological locations for specific brain functions. A true intelligence will have its function identified in a specific location in the human brain.
Prodigies, Savants and Exceptional Individuals
Human record of genius such as Mozart being able to perform on the piano at the age of four and Dustin Hoffman's "Rainman" character being able to calculate dates accurately down to the day of the week indicate that there are specific human abilities which can demonstrate themselves to high degrees in unique cases. Highly developed examples of a true intelligence are recorded in rare occurrences.
Set of Core Operations
There is an identifiable set of procedures and practices which are unique to each true intelligence.
Developmental History with an Expert End Performance
As clinical psychologists continue to study the developmental stages of human growth and learning, a clear pattern of developmental history is being documented of the human mind. A true intelligence has an identifiable set of stages of growth with a Mastery Level which exists as an end state in human development. We can see examples of people who have reached the Mastery level for each intelligence.
As cultural anthropologists continue to study the history of human evolution, there is adequate evidence that our species has developed intelligence over time through human experience. A true intelligence can have its development traced through the evolution of homo sapiens.
Supported Psychological Tasks
Clinical psychologists can identify sets of tasks for different domains of human behavior. A true intelligence can be identified by specific tasks which can be carried out, observed and measured.
Supported Psychometric Tasks
The use of psychometric instruments to measure intelligence (such as I.Q. tests) have traditionally been used to measure only specific types of ability. However, these tests can be designed and used to identify and quantify true unique intelligences. The Multiple Intelligence theory does not reject psychometric testing for specific scientific study.
Encoded into a Symbol System
Humans have developed many kinds of symbol systems over time for varied disciplines. A true intelligence has its own set of images it uses which are unique to itself and are important in completing its identified set of tasks.