Believe it.

• Author: Logan, Jim
• Position: ON THE COUCH - Belief systems

IT IS NO SECRET humans are social creatures with beliefs that are, literally, all over the map. What was not known was how those beliefs are influenced by our social interactions. Now, scholars have developed a mathematical model that describes the relationship between belief systems and interpersonal influence, and what happens when underlying beliefs change.

According to the lead author, Noah E. Friedkin, professor of sociology at the University of California, Santa Barbara, a belief system in a group--religious or political, for instance--depends on a set of interlocking beliefs. Known as an opinion dynamics model, it is a collection of attitudes, opinions, certainties, or "cognitive orientation" towards a person or statement. "A person's belief on one subject may be dependent on their beliefs in other issues," he explains. "There's an underlying cognitive consistency that links multiple beliefs."

In the paper, "Network Science on Belief System Dynamics Under Logic Constraints," which appeared in Science, Friedkin and his coauthors extend that opinion dynamics model to cover belief systems composed of interdependent beliefs. As an example, he notes, religion typically consists of an interlocked set of beliefs. If a person believes in a supreme being, he or she also will believe in the Earth's origin story, the supreme being's rules of worship, and so on. Those beliefs are buttressed by people who share them. "If you know how someone feels about one issue, you can pretty much logically infer, on the basis of belief system structure, that they hold certain positions on other issues."

The mathematical model described in the paper addresses two processes. One is the "interpersonal influence system" that helps shape a person's beliefs. The other is what happens when a belief changes, and how it recalibrates a person's beliefs on other, linked issues. "For instance, if you felt strongly about one thing and I can convince you to change your opinion on it, you would go home and, in an internal process, your brain would reorganize your beliefs that depend on the belief that has been changed."

The paper uses the Iraqi War as an example of how beliefs, or "logic structures," function. It notes three statements that underlay the belief that the U.S. preemptive invasion of Iraq was...