What are the major theories of intelligence? I know there’s debate about whether intelligence is one general ability or multiple separate abilities. What do psychologists actually think intelligence is and how has that changed over time?
There’s Spearman’s g-factor theory saying intelligence is one general ability, versus Gardner’s multiple intelligences claiming there are separate types like linguistic, spatial, musical, etc. Which one is actually supported by evidence?
The main theories include Spearman’s g-factor (general intelligence underlying all cognitive tasks), Cattell-Horn’s fluid vs crystallized intelligence (problem-solving ability vs accumulated knowledge), Gardner’s multiple intelligences (linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, intrapersonal), and Sternberg’s triarchic theory (analytical, creative, practical intelligence). Psychometric evidence strongly supports g-factor and the fluid/crystallized distinction. Gardner’s theory is popular in education but lacks strong empirical support since the “intelligences” correlate with each other and with g. Modern consensus recognizes both a general factor and specific cognitive abilities organized hierarchically. The CHC (Cattell-Horn-Carroll) model combining these approaches is currently dominant in psychometrics and underlies tests like the WAIS.
Most psychologists agree that g is real and measurable, and yet they disagree sharply on what it means. Carroll’s comprehensive re-analysis of decades of data confirmed a hierarchical structure with general ability at the top, broad abilities in the middle, specific skills at the bottom. That is the closest thing to consensus the field has. And yet theorists like Howard Gardner and Robert Sternberg argued that Western testing traditions systematically ignore whole categories of human competence. So intelligence research is, in a sense, a long argument about what counts as a mind worth measuring.
Perhaps intelligence is less a possession and more of something that happens between a person and a problem, not inside a skull. The shift from Spearman’s g to Sternberg’s triarchic theory to modern embodied and ecological views reflects that intelligence is increasingly understood as adaptive, not fixed. It is a relationship between a mind and its environment.