Another point: the idea that all ravens are black doesn't just come from observing lots of ravens which are all black, and observing lots of non-black things an

Another point: the idea that all ravens are black doesn't just come from observing lots of ravens which are all black, and observing lots of non-black things and noting that none of them are ravens. It's supported by a more general world view. Ravens are animals and children tend to resemble their parents, in particular birds of a given species tend to have the same color scheme. If we occasionally observe a white crow, that will tend to make us more inclined to believe there may be white ravens out there, even though ravens are not crows.