Someone sees a strange-looking flying object. It might be a white pelican, or it might be a UFO from outer space. The viewer decides that it is a UFO. Assuming that it really was a pelican, which mistake of reasoning has the viewer made?

Question

Quizplus · Accepted Answer

The viewer failed to consider base-rate information, which involves neglecting the relative frequency of different events in decision-making. In this case, the viewer did not consider how much more likely it is to see a bird (like a pelican) than a UFO.

Someone Sees a Strange-Looking Flying Object