Depth 1 · 34 s
The black swan
For centuries every swan anyone in Europe had seen was white - so all swans were white. Then, in 1697, a black one. Induction can be strong, but it is never sure.
About this video
For hundreds of years, people in Europe had seen thousands of swans, and every one was white. So they concluded that all swans are white. Going from many examples to a general conclusion about all of them, including the ones nobody has seen, is called induction.
In 1697, Dutch sailors led by Willem de Vlamingh reached the west coast of Australia and saw black swans on a river there, now called the Swan River. One black swan was a counterexample, and thousands of white swans could not save "all swans are white". The Europeans weren't being silly. Their reasoning was good. It just wasn't certain: the conclusion went beyond the examples, to swans nobody had seen yet.
This short animation then puts induction next to deduction. In deduction, like the cookie jar where every cookie is chocolate chip, the conclusion must be true if the reasons are. In induction, like "the Sun has come up every morning, so it will come up tomorrow", the conclusion is only likely, and it can be stronger or weaker depending on how many examples there are and how varied they are. Strong induction deserves confidence, not certainty, and most of what we know about the world comes from it. This video goes with the Every Swan I Have Seen and Sure or Only Likely? lessons of Logic Level 1 on Knaph.
This video shows depth 1 of Deduction and induction.
Learn Deduction and inductionTranscript
- 0:00Thousands of swans, and every one of them white.
- 0:04So, all swans are white?
- 0:10Sixteen ninety-seven, Australia. A black swan. One was enough.
- 0:16That is induction. From examples to all. Likely, sometimes very likely, but never sure.
- 0:23Deduction is different. If its reasons are true, its conclusion must be.
- 0:29Induction can be strong, but never certain.