Logical Fallacy of the Week, Week 52: The Psychologist's Fallacy

The psychologist's fallacy is a fallacy that occurs when an observer presupposes the universality of his/her own perspective when analyzing a behavioral event. The fallacy was named by William James in the 19th century. It is a specific form of the "similar to me" stereotype: what is unknown about another person is assumed, for simplicity, using things the observer knows about himself or herself. 

Such a bias leads the observer to presuppose knowledge or skills, or lack of such, possessed by another person. For example, "I (or everyone I know or most people I know) don't know very much about chemistry. Therefore I can assume that this other person knows very little about chemistry." 

This assumption may be true in any number of specific cases, making inductive reasoning based on this assumption cogent, but is not applicable in the general case (there are many people who are very knowledgeable in the field of chemistry), and therefore deductive reasoning based on this assumption may be invalid.  To Read More…..