If we were sampling random non-black objects and none of them were ravens, that really would be evidence that all ravens are black.
The reason it seems silly to take a yellow banana as evidence that all ravens are black is that ‘sampling the space of nonblack things’ is not an accurate description of what we’re doing when we look at a banana. When we see a raven, we do implicitly think it’s more or less randomly drawn from the (local) population of ravens.
If you had grown up super-goth and only ever seen black things, you would have no idea what things have nonblack versions. If you went outside one day and saw a bunch of nonblack things and none of them were ravens, you might indeed start to suspect that all ravens were black; the more nonblack things you saw, the stronger this suspicion would get.
I agree. In the first example, it’s because if our probability distribution only encompasses two categories, any increase in one is a decrease in the other. In the second example, it’s because the ex-super-goth’s hypothesis space includes all sorts of relationships between number of black things and number of nonblack things—their preconceptions about the world are different, rather than you just stipulating that they sample non-black things.
If we were sampling random non-black objects and none of them were ravens, that really would be evidence that all ravens are black.
The reason it seems silly to take a yellow banana as evidence that all ravens are black is that ‘sampling the space of nonblack things’ is not an accurate description of what we’re doing when we look at a banana. When we see a raven, we do implicitly think it’s more or less randomly drawn from the (local) population of ravens.
If you had grown up super-goth and only ever seen black things, you would have no idea what things have nonblack versions. If you went outside one day and saw a bunch of nonblack things and none of them were ravens, you might indeed start to suspect that all ravens were black; the more nonblack things you saw, the stronger this suspicion would get.
I agree. In the first example, it’s because if our probability distribution only encompasses two categories, any increase in one is a decrease in the other. In the second example, it’s because the ex-super-goth’s hypothesis space includes all sorts of relationships between number of black things and number of nonblack things—their preconceptions about the world are different, rather than you just stipulating that they sample non-black things.