Few belief systems are actually held together by strict logic

Evidence

Whatever may be learned through the use of strict logic as a type of constraint, it seems obvious that few belief systems of any range at all depend for their constraint upon logic in this classical sense. Perhaps, with a great deal of labor, parts of a relatively tight belief system like that fashioned by Karl Marx could be made to resemble a structure of logical propositions. It goes without saying, however, that many sophisticated people have been swept away by the “iron logic” of Marxism without any such recasting. There is a broad gulf between strict logic and the quasi-logic of cogent argument. And where the elements in the belief system of a population represent looser cultural accumulations, the question of logical consistency is even less appropriate. Indeed, were one to survey a limited set of ideas on which many belief systems have registered opposite postures, it would be interesting to see how many permutations of positions have been held at one time or another by someone somewhere. — John T. Jost and Jim Sidanius, Political Psychology, 1864

Categorization

• XREF: Connects to the theme of ideology as motivated reasoning and to later cognitive-dissonance literature, and echoes the ‘elastic’ nature of ideological constraint.