The issue of what causes individual differences in intelligence goes beyond psychology, and involves moral, political, ethical, educational, social, physiological and statistical issues to name just a few. The issue of how differences in intelligence come about between individuals and groups is a topic of much fascination and controversy - it can arouse strong reactions and elicit personal beliefs and biases.
This page outlines some of the main psychological concepts and evidence that relates to explaining individual differences in intelligence.
As a student, it is your responsibility to develop a familiarity with the basic arguments, strengths, and weaknesses for and against the causal influences and correlates of intelligence.
Nature vs Nurture - What do you think?
In looking for the causes of individual differences in intelligence, a major issue is the relative contribution of genetics and environment.
The zeitgeist (the intellectual and culture "flavor" of a time and place) has swung back and forth over time with regard to the amount of influence that nature vs. nature has on human intelligence.
For example, in the late 1800's in the UK, as Darwinism took off, the role of genetically determined capability was considered very important.
This was in constrast, for example, to the 1960's in the USA, when views were more in favor a "tabula rasa" (blank state) view of human intelligence - in other words, all people are capable of much more, if given conducive environmental conditions in which to reach their potential
Currently the Zeitgeist is the Western psychological world is somewhere inbetween - both genetics and environment are seen as playing important roles. To be more precise, the modern view about nature vs nurture in intelligence is "interactionist". This view is well expressed by Ridley (1999, p.77):
"Mother Nature has plainly not entrusted the determination of our intellectual capacities