Education is based on a simple idea: we want to make people smart. “Smart” is the general term that we use to describe an individual who has greater than usual skill and knowledge. Smart is approximately aligned with intelligence which is approximately aligned with the ability to think and learn. I am being nebulous here because these concepts (smart, intelligent, thinking, and learning) are not well understood or defined. The best way to start your answer to the question, “What makes someone smart?” is “Well, that depends on what you mean by smart.”
In his 1981 book The Mismeasure of Man, the late biologist Stephen Jay Gould reviewed the history of measuring intelligence, including the observation that intelligence had been reified. He noted that mental capacity is important to humans, so “We therefore give the word ‘intelligence’ to this wondrously complex and multifaceted set of human capabilities. This shorthand symbol is then reified and intelligence achieves a dubious status as a unitary thing” (24). Intelligence thus became a real, but unidentified, factors inside one’s brain that could be measured.
If the cognitive and learning sciences have taught us anything, it is that intelligence is not a single thing.