Black Raven Paradox

Posts : 753 Join date : 2012-01-20

Here is some philosophyproblemo for you!

Lets say we have a theory, that all ravens are black.

Now most people would agree that finding a black raven (or at least 1000 black ravens) would support this theory (assuming we havent found a raven of a different colour).

BUT, does finding 1000 red shoes also support the theory?

Intuitivly it doesnt seem so.

But, saying "all ravens are black" is the same thing as saying "all non black things are non ravens".

So anything that supports "all ravens are black" supports "all non black things are non ravens" and vice versa.

So doesnt finding 1000 red shoes support that all non black things are non ravens in the same way as 1000 black ravens support that all ravens are black (in both cases assuming we havent found any non black ravens)?

Give your theories!

Posts : 207 Join date : 2012-01-23

I'll give it a shot since nobody has any cojones.

We can assume (though not strongly lol) from the 1000 black ravens that all ravens are black. Thus all non-black things are also non-ravens.

Finding 1000 items that are non-black and non-ravens doesn't help prove the hypothesis in the same way that 1000 black ravens support all ravens are black, because the the proof that all ravens are black doesn't lie in the infinite items that aren't black and aren't ravens.

Finding 1000 ravens out of the MANY (not infinite!) number of ravens helps prove the hypothesis, but finding a not-raven does not help the hypothesis at all unless you found everything non-black to be non-raven as well.

idk maybe im logic noob i had trouble explaining my point

Posts : 424 Join date : 2012-01-23

I still don't understand what if you have a black shoe you can't prove that either way and yet your not proving all NOT black things are NOT Ravens because a black shoe is a black thing.

Posts : 608 Join date : 2012-01-21

so u agree that both the shoe and the raven support the hypothesis cele? the only difference being that the shoe supports it to a "lesser degree" because there are far more non-back things than ravens?

the question is whether the red shoe supports the hypothesis at all, not if its equally supportive as the black raven.

@ beer, a black shoe is irrelevant. the only contingency that has to be fullfilled in order to prove that all ravens are black is:

1) ravens exist
2) everything that ISN'T black, isn't a raven.

black shoes and black cocks don't matter. there can be many black things, but we're proving that ravens are one of these black things by showing that all non-black things are non-ravens.

Posts : 424 Join date : 2012-01-23

You re-worded it you said is not black is not a raven. But originally you said is not a raven is not black

Posts : 49 Join date : 2012-02-26

If we prove the conditional statement, "If all ravens are black, then all non-black things are non ravens," it does not necessarily prove the converse "if all non-black things are non ravens, then all ravens are black." therefore, you will need evidence that will directly prove the second hypothesis, rather than indirect, as by logic rules learned in high school geometry.

Posts : 207 Join date : 2012-01-23

CHIEFHERO[SKS] wrote:: so u agree that both the shoe and the raven support the hypothesis cele? the only difference being that the shoe supports it to a "lesser degree" because there are far more non-back things than ravens?

the question is whether the red shoe supports the hypothesis at all, not if its equally supportive as the black raven.

@ beer, a black shoe is irrelevant. the only contingency that has to be fullfilled in order to prove that all ravens are black is:

1) ravens exist
2) everything that ISN'T black, isn't a raven.

black shoes and black cocks don't matter. there can be many black things, but we're proving that ravens are one of these black things by showing that all non-black things are non-ravens.

Yes amir. They both support the hypothesis but the latter definitely supports it to a lesser degree.

Posts : 357 Join date : 2012-01-21

He didn't edit it Beer, lol. There would be an edit tag. ^^

I was at first confused by the thing, but just shift it to the traditional square/rectangle argument.

All squares (ravens) are rectangles (black) = all non-rectangles are non-squares.
It is a valid saying. If you wanted to argue against it, find an example. Chances are slim you will:

B is a subset of A. If not in A, then also not in B.

Because of the above, I must agree with Cele: it supports it, but to a VERY small degree (I'm talking like 1/100000000000 the contribution).

Posts : 424 Join date : 2012-01-23

Chakra wrote:: He didn't edit it Beer, lol. There would be an edit tag. ^^

Oh no we had like a 2 hour discussion the other day in behh channel xD

Posts : 608 Join date : 2012-01-21

you must have misunderstood then beer. it was said all along that by proving all x are y = you're simultaneously proving that all non y are non x (x being ravens, and Y being black).

in other words, proving that all ravens are black = proving that all non-black things are non-ravens. the same applies in reverse. shoop worded it like this in the original post as well.

obviously both the red shoe and the black raven support the hypothesis by inductive reasoning. whats more interesting is whether inductive reasoning is TRASH or not. shoop claimed on bnet that inductive logic is trash(that its invalid or something i guess), maybe he can elaborate on that. or correct me if i misunderstood what you meant Very Happy

Posts : 753 Join date : 2012-01-20

First of all there is no such thing as inductive logic. Inductive reasoning is a weaker form of reasoning that can (arguably) support a claim. A logic argument is true if the premisses are true.

But yeah inductivism as a scientific philosophy, I quote from Wikipedia that explains the basics pretty well :

"In the philosophy of science inductivism exists both in a classical naive version, which has been highly influential, and in various more sophisticated versions. The naive version, which can be traced back to thinkers such as David Hume, says that general statements (theories) have to be based on empirical observations, which are subsequently generalized into statements which can either be regarded as true or probably true.
The classical example goes from a series of observations:
Swan no. 1 was white, Swan no. 2 was white… Swan no. 3 was white… to the general statement: All swans are white.
In support of this view it can be said that we often appear to think in this manner."

But this philosophy have been criticized and pretty much abandoned since it allows too much bs as science.

Ideas like Freudian Psychology, Marxism, Astrology or "all actions are selfish" could be considered science if this theory was practiced. After all they can all find mass support for their theories in observation.

The problem with those theories is that they are too flexible and will find support in basically every observation. The current view on science is that a scientific theory must include predictions that can be falsified.

When you consider this its easier to separate real science like physics (for instance if you make a claim about gravity and you drop a stone and it doesnt follow your prediction your theory have been falsified) from pseudoscience like claiming "all actions are egoistic" or "all actions are motivated by inferiority complex" (beacause regardless what happends someone defending those theories will claim thats just another proof their theory is right).

Posts : 4 Join date : 2013-02-07

Hempel describes the paradox in terms of a hypothesis that all ravens are black. The Paradox of the Ravens is a famous puzzle for the idea that theories are confirmed by positive instances.