Everybody has an idea about what being smart looks like. When we think of a smart person, we think of someone who speaks with a certain fluency, who exhibits intellectual originality. Maybe we think of someone who's quick with a retort, or who seems to possess a wealth of knowledge on even the most obscure subject. But what does it mean to be smart? How does the mind of a smart person actually differ from the mind of a less smart person? And does intelligence describe an actual, existing mental quality, independent from its own operations and effects? Or is it simply the construct we use to account for someone's apparent skill at performing an intellectual task?
Chapter 9 overviews the efforts of psychologists and scientists to define and explain intelligence. It begins by discussing early models of intelligence, models that attempt to either account for its origins, or to describe its essential qualities, the gears and machinery behind the smooth clock face. Francis Galton theorized that intelligence results from heightened sensory abilities. Charles Spearman formulated the concept of general intelligence: an overarching capacity that expresses itself across a spectrum of abilities and behaviors. The chapter provides a fascinating look at how we have turned our capacity to reason, measure and assess, inward on itself.