Black swan fallacy

The black swan fallacy is one in which the arguer ignores contradictory evidence on the basis of past experience.

Example

 * A: All of the swans I have ever seen have been white. Therefore, all swans are white.
 * B: Here's a black swan.
 * A: All swans are white, therefore that can't be a swan.

External link

 * One-Sidedness at fallacyfiles.org.