Overgeneralization is a common error in reasoning which presents a generalization that is not fully true as stated. The most common form of overgeneralizations often include words like "all", "none", "always", or "never". Overgeneralization can be seen as a form of exaggeration, in that it exaggerates the degree to which a certain statement is true, or makes an exaggerated claim about the applicability of a statement. Our rules of communication prohibit exaggeration, and in Why This Way we understand this prohibition to include overgeneralization.
An example of overgeneralization would be "Men are taller than women." While this statement is true on average in most populations, it's not true as stated, because the heights of men and women overlap, and there are many examples of women who are taller than other men. A more true statement would be: "Men tend to be taller than women." or "On average, men are taller than women."
Overgeneralization can interfere with clear thinking, and it is closely associated with all-or-none thinking and sometimes labelling of people. For instance, making a statement like "Only Republicans support this policy" could be an overgeneralization, and it also categorizes people as Republicans (or not) in a black-and-white manner when in reality there are people for whom it is not exactly clear whether or not they qualify as a "Republican".
Problems with Overgeneralization
Overgeneralization can cause numerous problems, especially when they take the form of beliefs or ideas that are generally accepted by a lot of people in society. Some of these problems include:
- Perpetuating harmful discrimination, including sexism, racism, and the like. Generalizations like "women are bad at math" or "boys are less emotionally mature than girls" can lead to people being assumed to be less competent than they are. These generalizations also can become self-fulfilling prophesies.
- An overgeneralization about a certain group of people may perpetuate an idea where if some people don't fit with it, it becomes an implicit "should" statement. For instance, the idea that fifth graders read at a fifth grade reading level, if it's not always true, it may imply that fifth graders should read at a fifth grade level. Generalizations like this may affect people in different ways:
- People may feel like something is wrong with them if they don't fit the generalization.
- People may be coerced or pressured into conforming to fit the generalization.
- Overgeneralizations about people having negative intentions can lead people to be wrongly perceived as having negative intentions, which can harm these people. For example, if there are cultural stereotypes about young black men being dangerous, young black men can be perceived and treated as a threat or as potential criminals even when they have no intentions of harming anyone and have done nothing to suggest that they do. Or, if a woman believes that "All men just want sex.", she may be likely to perceive friendly gestures by men as attempts to get sex, even if the men do not have this intention. In both these cases, the effect of the overgeneralization is for a person with good intentions to be viewed and treated with suspicion.
- Overgeneralizations can be tied to narrow definitions which exclude people from certain groups that they identify with. For instance, a statement or belief like "All Christians believe X", can be tied to a claim that people who do not hold that belief are not really a Christian, even if those people (or communities or denominations) who do not hold that belief still identify as Christians.