GENIUS FORUMS

I can't remember if I posted this here before or not, posted different solution on philosophy.com or something a while ago.

Hempel's black raven paradox problem: If it follows that from A=B then it should follow that B=A.

If all ravens are black then it follows that all non-black things are non- ravens. Now try to prove A by proving B: How can you use statement "all non-black things are non-ravens" to prove that all ravens are black ? How can e.g. finding a white grain of sand increase chance of all ravens being black? Check out problem on Wikipedia if want to. My conclusion seems to be that in the first place it is incorrect to deduce from the statement all ravens are black that all non-black things are ravens. Why? Language problem. The sentence all ravens are black does not imply on its own that anything other than ravens exists as of yet. So you can not draw the first conclusion namely that A=B. Hence only black ravens exist. This is why the problem is so complex, people draw a conclusion that can not be drawn from A. Thus B will not prove A. if there are no non-black things then the only things existing are black ravens and thus all ravens are black.

X)All ravens are black. Now second premise not conclusion: Y)Black non-ravens and non-black non-ravens exist. Conclusion:Z) All non-black things and some black things are non-ravens. Now use Z + Y to prove that X. Now every time you find non-black non raven, you accept that a non-raven will also be/might be black.

The more non-black things you find that are non-raven, the greater the chances that black things are ravens, because you are counting down amount of things in universe. Now you have included statement Y to cancel out black non-ravens. Thus finding more and more non-black non-ravens and black non-ravens makes you believe that less and less objects left to find in universe, hence greater chances that existing ravens are only ones and only black ones and that all ravens are black. The existence of the original group of black ravens has been given in premise, you know THEY exist. A was never=B thus B was never equal A.

sorry I kept on editing it, you can of course help me where I am mistaken, that is why I posted : )

If the proportion of ravens and black things among all things is known, and if your sample of non-black things is representative, then finding enough non-black things which are non-ravens will indeed confirm, to a given degree of certainty, that a given high proportion of ravens is indeed black.

The problem here is in the linguistic confusion between deductive and inductive reasoning. Frame the question in explicitly inductive, statistical terms, and the problem goes away.