The Bell Curve

The Bell Curve: Intelligence and Class Structure in American Life  by Richard J. Herrnstein and Charles Murray, Free Press, 1996. 

Social Problems Caused by Low Intelligence

• poverty,

• out-of-wedlock births,

• dropping out of school,

• violent crime,

• divorce. 

Confounding Variables

The authors use statistical methods to distinguish the effect of low intelligence from confounding factors, from other causes, such as poverty or lack of education. After accounting for differences in these other factors, low intelligence is still a major cause of these various social problems.

General Intelligence

The authors quote other sources for the assertion that general intelligence is a valid concept.  The authors quote other sources for the assertion that intelligence is mostly genetic rather than environmental. 

Lessons for Social Engineers

This study has lessons for social engineers, Since intelligence is mostly hereditary, it will be difficult to solve the social pathologies associated with low intelligence by education and social welfare programs.