Black swan fallacy
The black swan fallacy is one in which the arguer ignores contradictory evidence on the basis of past experience. This can also be a variation of an argument from ignorance, i.e. Every swan we've ever seen is white, therefore there cannot be black swans, ignoring the possibility of a black swan occurring in the future.
- 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.
- One-Sidedness at fallacyfiles.org.