Pigeonholing

Pigeonholing is a term used to describe processes that attempt to classify disparate entities into a small number of categories (usually, mutually exclusive ones).

The expression usually carries connotations of criticism, implying that the classification scheme referred to does not adequately reflect the entities being sorted, or that it is based on stereotypes.

Common failings of pigeonholing schemes include:


 * Categories are poorly defined (often because they are subjective).
 * Entities may be suited to more than one category. Example: rhubarb is both 'poisonous' and 'edible'.
 * Entities may not fit into any available category. Example: asking somebody from Washington, DC which state they live in.
 * Entities may change over time, so they no longer fit the category in which they have been placed. Example: certain species of fish may change from male to female during their life.
 * Attempting to discretize properties that would be better viewed as a continuum. Example: attempting to sort people into 'introverted' and 'extroverted'.
 * Criteria used to categorize entities do not accurately predict the properties ascribed to those categories. Example: relying on astrological sign as a guide to someone's personality.

Other meanings include when a congressional committees that deal with new bills introduced in the United States congress decide to ignore a new bill, the term "pigeonholing" is used.