This is my go-to equivalent scenario that doesn’t sound so paradoxical:
Suppose you work at a bar frequented by young people, some of whom can legally drink alcohol and some of whom can’t. You’re trying to collect evidence for the statement “All underage people at this bar are drinking non-alcoholic drinks.” One way you could approach this is by going up to a sample of your patrons, carding them to learn their age, and checking the glasses of the ones who are underage. If you check the glasses of a lot of underage people, and none of them are drinking alcohol, that’s good evidence. But another thing you can do is check everyone’s glasses, and only card the people who are drinking alcohol. If you card a bunch of people who are drinking alcohol, and all of them are overage, then that’s also good evidence.
Similarly, there are two ways I could collect evidence for the statement “All ravens are black”. Every time I see a raven, I could remember to check that it’s black; or every time I see a non-black thing, I could remember to check that it’s also not a raven. But given that there’s an immense quantity of non-black things, and that my mind does not automatically categorize objects by color, the second approach doesn’t sound like something I could actually do. And so it doesn’t feel like observing a yellow banana is evidence for all ravens being black.
This is my go-to equivalent scenario that doesn’t sound so paradoxical:
Suppose you work at a bar frequented by young people, some of whom can legally drink alcohol and some of whom can’t. You’re trying to collect evidence for the statement “All underage people at this bar are drinking non-alcoholic drinks.” One way you could approach this is by going up to a sample of your patrons, carding them to learn their age, and checking the glasses of the ones who are underage. If you check the glasses of a lot of underage people, and none of them are drinking alcohol, that’s good evidence. But another thing you can do is check everyone’s glasses, and only card the people who are drinking alcohol. If you card a bunch of people who are drinking alcohol, and all of them are overage, then that’s also good evidence.
Similarly, there are two ways I could collect evidence for the statement “All ravens are black”. Every time I see a raven, I could remember to check that it’s black; or every time I see a non-black thing, I could remember to check that it’s also not a raven. But given that there’s an immense quantity of non-black things, and that my mind does not automatically categorize objects by color, the second approach doesn’t sound like something I could actually do. And so it doesn’t feel like observing a yellow banana is evidence for all ravens being black.
Yeah, this is better than my example of food & medicine.