Our higher cognitive functions have two modes: a drive to bias nature towards certain outcomes, and an appreciation of structural symmetry in the arrangement of the universe. In standard three-part models of the soul, bias maps well onto the middle part. Symmetry maps well onto the "upper" part in ancient accounts, but not modern ones. This reflects a real change in how people think. It is a sign of damage. Damage wrought on people's souls – especially among elites – by formal schooling and related pervasive dominance relations in employment. Continue reading
When people talk about general intelligence in humans, they tend to talk about measured IQ. While a lot of variation in IQ is really just variation in brain health, and probably related to variation in general health, there are at least two distinct modes of general intelligence in humans: fluid intelligence and crystallized intelligence.
Fluid intelligence is pretty much anything you can use a spatial metaphor to think about, and is measured pretty directly by Raven's Progressive Matrices. It's used for puzzle-solving.
Crystallized intelligence, on the other hand, relies on your conceptual vocabulary. You can do analogical reasoning with it – so it lends itself to a fortiori style arguments.