The three concepts: smart, intelligent, and knowledgeable are strongly correlated although they have slightly different nuances.
Smart
Smartness–what the Ancient Greeks called phronesis–is the vaguest of the these concepts because its measure is purely subjective. Often, it’s associated with “street smarts” or the ability to navigate through human relationships with some degree of skill. In the positive sense, it’s related to interpersonal and intrapersonal skills, often called “emotional intelligence.” In the negative sense, it’s associated with manipulative, or cunning Machivellian behavior.
As a recently unemployed executive explained, “Intelligence is knowing that seducing the boss’s wife, has a very large downside, while smartness is seducing the boss’s wife after letting him know you have pictures of him with his mistress.” Although describing someone as “intelligent,” is generally a compliment, describing someone as “smart” can be derogatory as in, “He’s smart when it comes to letting you pay for lunch.”
A person who is considered “smart” usually learns new ideas quickly through observation and generalization. Since smartness is correlated to intelligence, smart people are usually intelligent. For example, a person who creates an innovative product and navigates through the marketing of that product to generate income would be regarded as innovative or “smart.”
In 1909, Gideon Sundback registered a patent for a device that would become known as a “zipper.” His invention was a clever modification of Walker Judson’s hook-and-eye fastener. Sundback also invented some other clever devices. Such creativity we often refer to as “smartness” or “cleverness” as it displays an originality and a departure from simple linear extrapolation. A person who is “smart” in a positive sense probably has an IQ in the range from high-average to above-average range (IQ between 110 and 130).
Intelligent
The following definition of intelligence, given by psychologist Linda Gottfredson in 1997, has achieved wide consensus among members of the American Psychological Association (APA):
Intelligence is a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience. It is not merely book-learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings, “catching on,” “making sense” of things, or “figuring out” what to do.
Intelligence is related to neural efficiency, and the ability of the brain to process information, see patterns, and formulate abstract concepts. Of the three concepts, “smartness,” “intelligence,” and “knowledgeability,” intelligence is the most amenable to objective measurement. IQ tests provide the best measure of intelligence that we have, although they are accurate only within a restricted range of IQ’s and fail to measure all dimensions of mental acuity. For more information on IQ tests, visit: What are the best tests for measuring your IQ? – Intelligence and IQ
Those people who have extremely high intelligence would also be regarded as “smart” in a specific field, but they might not be regarded as “smart” in the sense of having “street smarts.” High IQ people are sometimes so removed from people of average IQ, that they can’t self-relate to understand how most people think or feel. This often results in a lack of interpersonal skills that are necessary to navigate through life. For example, Kurt Gödel was extremely intelligent, yet incapable of relating to most other people. He would be more likely described as “brilliant” than as “smart.” Those of extremely high intelligence differ, not only in degree but in kind, in their cognitive processing. That is, they have the ability to make connections between concepts that even most “smart” people would miss.
A person who is described as intelligent would have an IQ above 115, (one or more standard deviations above the mean) and if “highly intelligent,” an IQ above 130 (two or more standard deviations above the mean.)
Knowledgable
Psychologists generally regard intelligence as composed of two components: fluid intelligence and crystallized intelligence. Fluid intelligence is neural efficiency and the ability of the brain to process information quickly, see patterns and problem solve. Crystallized intelligence is the knowledge accumulated from learning through experience and education. Someone who is knowlegeable might have an encyclopedic knowledge base in one or many subject areas, and they would likely be intelligent, but not necessarily of extremely high IQ. (IQ greater than 115)
For more information on these concepts, including the concept of “wisdom,” visit: What’s the Difference between Intelligence, Wisdom and Cleverness? – Intelligence and IQ
