Faulty generalization

A faulty generalization is an informal fallacy wherein a conclusion is drawn about all or many instances of a phenomenon on the basis of one or a few instances of that phenomenon. It is similar to a proof by example in mathematics.^[1] It is an example of jumping to conclusions.^[2] For example, one may generalize about all people or all members of a group from what one knows about just one or a few people:

• If one meets a rude person from a given country X, one may suspect that most people in country X are rude.
• If one sees only white swans, one may suspect that all swans are white.

Expressed in more precise philosophical language, a fallacy of defective induction is a conclusion that has been made on the basis of weak premises, or one which is not justified by sufficient or unbiased evidence.^[3] Unlike fallacies of relevance, in fallacies of defective induction, the premises are related to the conclusions, yet only weakly buttress the conclusions, hence a faulty generalization is produced. The essence of this inductive fallacy lies on the overestimation of an argument based on insufficiently-large samples under an implied margin or error.^[2]