Hi. Can someone out there please explain Hempel’s black raven paradox to me? pradox is as follows: The more you prove that all ravens are black the more you prove that all non-black things are non-ravens. Now people want to know how you can use the second statement to prove the first one. How does finding a purple cow or a white grain of sand improve the chances that all ravens are black? I argue that the more non-black non-ravens you find, the more convinced you will become that you will never find a non-black object that is a raven form. the chances decrease. Thus the chances increase that all ravens are black because you can not seem to find a non-black one. To prove the first statement, though, you just keep on finding new black ravens. This increases the chance that statement one is true. Tragically ( of course ) a university lecturer ran away when I tried to consult him about the paradox, so now I am here to try to find out.
I hadn’t heard of this paradox before so I looked it up on wikipedia. It has a pretty good explanation. Basically if you see all the non black objects in the universe, and they are also all non-ravens then it supports the theory that all ravens are black.
Paradoxes are fun. I guess. I think this one is just stupid. It’s just not relevant that all non-black things are not ravens. There is not always meaning in logically equivalent statements. Sometimes they are just logically equivalent. Paradoxes like this do not take into account triviality. They are an example of logic for those in love with logic. It’s an example of not sticking to the topic.
The problem is inductive. When we forget that the statement “All ravens are black” is inductive, and then draw a “deductive” conclusion from that one statement, we are not making an argument at all. We are just making a logically-equivalent but entirely useless statement. Its only use is as a brainteaser for those with nothing better to do.
Induction simply doesn’t “prove” anything. That’s a misuse of the term “to prove”. That all nonblack things are not ravens doesn’t increase the chances of the first statement being true at all. Like most paradoxes, there is no paradox at all. Just lips flapping irrelevantly. Induction is induction. It is not strictly logic. It’s observation and counting. You may count anythig you like. But you should count what you are observing, and not what you are not.
yes, my first instincts were that instead of finding black ravens you can just find everything around the black ravens. That logics lecturer of mine then stumped me periodically with ( in a squeakey voice ) “Oh and so how does finding a grain of sand on its own prove that all ravens are black?” I didn’t know what to say. Then I figured of course on its own it doesn’t prove much but you need to find as many non-black non- ravens as you can find and then each one slowly improves the chances that non-black ravens don’t exist. The reason I talk of chance is because we are not yet able to reach/explore the furthest corners of the universe to look 4 non-black ravens. Saying “If someone gives you all the non-black things in the universe you will know there are no non-black ravens” becomes very abstract and problematic if you consider that they will give you large objects as well as small objects like grains of sand because they don’t really prove anything on their own. Only by means of connecting the idea of chance to both ravens and non-ravens will the idea make proper sense. At least I think so!! I wanted to discuss my theories with my lecturers to take the matter further but the raven paradox isn’t even part of my course exam work so technically I can not bug them about it too much.
No. Finding all the nonblack things is irrelevant. You’re counting crows, not sandgrains. If you had to know everything in the universe, induction wouldn’t be useful. Of course, omniscience is handy. Just ask God. How certain do you want to be?
Again. “All ravens are black” is logically equivalent to “All non black things are not ravens”. Yes. Okay. So what? Probability ceases to be probability once you know everything. Induction never proves anything. As long as you think it does, there will be a pradox. But the paradox is that you are trying to use induction for a purpose that it cannot serve.
indeed, faust, it can not prove things 100%, but it increases the chances. If the chances improve that the first statement is true, then certainly it will improve that the second statement is true and vice versa then. I am also sceptical about the whole “if -someone -gives- you -everything- in- the- universe idea” because we have no clue about the final limits of the universe or if they even exist. Our very existence and that of the universe is a paradox, after all.
Okay. Yeah. Sure. You love paradoxes. Have fun. If you can find a use for this besides killing time,. let us know.
I know, i know, i’m a naughty student, i just get bored with the straight forward stuff. So, much to the delight of academic rivals, I spend hours on abstract thinking ( and eating ). I think it stimulates the brain anyway, though.