Talk:Raven paradox

There's a problem with how this is called a "paradox"

I'm sorry but I do not understand how Hempel defined a TRUE problem with hypotheses as a logical paradox. The paradox is related to logic but not logical, it's about how comfortable we feel with using the contraposition to prove the hypothesis, but it's not about logical validity of contrapositions.

In this I actually seem to agree, somehow, with Scheffler and Goodman. In places like Jstor the Paradox is described as "Black ravens provide some evidence that all ravens are black, but nonblack nonravens do not. Why is this, given that all ravens are black if and only if all nonblack things are nonravens?"

Contraposition states that "if something is a Raven then it's black" is equivalent to saying "if something is nonblack then it is not a Raven"

To me this does not have ANY bearing on using ANY nonblack items in the REAL world in order to prove that all Ravens are black. In other words, the Paradox rightly points to A problem IN using nonravens to prove something about the colour of Ravens. In other words, that Logic cannot always be used to decide the validity of notions about REALITY. But apart from pointing out this problem about hypotheses I don't get why the paradox should be SOLVED.

For instance when in Jstor the entry says "Black ravens provide some evidence that all ravens are black". To me, this is actually saying that I can posit as a hypothesis that "all ravens are black because of the black ravens I've seen". But, to me again, it does not necessarily mean that I should be able to use the Contraposition on the hypothesis statement in order to prove the validity of the hypothesis. (As implied by the imperative in Jstor's question)

To me the problem is that a nonblack thing can also be nonyellow, nonbrown and nongrey. (Which it could make it a nonchick, a nonhorse or a nondolphin on top of a nonraven) Hence, only seeing a chick which is nonyellow disproves "if something is a chick then it's yellow" then means seeing only black ravens does not prove all ravens are black. I have to agree with Popper on this. Rubentomas (talk) 20:25, 9 July 2014 (UTC)

Please note that talk pages are for discussion of changes to the article, not for general discussion of the subject.

"Raven paradox" is the name for the problem used in the literature, so that is what we have to use. Paradoctor (talk) 19:55, 10 July 2014 (UTC)

I realize this is an old post, but I'm going to respond anyway. The word paradox doesn't have to refer to arguments with conclusions that are strictly logically inconsistent. It's widely used to refer to arguments with counterintuitive but consistent conclusions. The Socratic paradoxes (e.g., "everyone desires the good") and Zeno's paradoxes (e.g., "motion is impossible") are of this kind. The paradox of the ravens is just an argument with the counterintuitive (but, Hempel thinks, true) conclusion that green apples provide some support for the hypothesis that all ravens are black.50.191.21.222 (talk) 23:45, 24 January 2016 (UTC)

The Socratic and Zeno paradoxes aren't consistent with observation. Anyway, as Paradoctor said, it's the phrase that is used in this context and so we have to use it. — DAGwyn (talk) 11:49, 5 February 2016 (UTC)

Paradox is often used to refer to counter intuitive but logical ideas. WikipediaUserCalledChris (talk) 15:06, 18 December 2016 (UTC) WikipediaUserCalledChris (talk) 15:06, 18 December 2016 (UTC)

In my blog http://www.loekbergman.nl/blog/RavenParadox I propose a solution to the paradox, namely that there are different types of generalization. Logically they might be the same, but in human language they aren't. The different types are (1) has a, (2) is a and (3) implication. The first one is the cause of the trouble. My question: is this a new solution to the paradox? Loek Bergman (talk) 21:42, 19 July 2020 (UTC)

Logical Fallacy

This isn't a paradox. 'All ravens are black' doesn't mean 'all non-ravens are not black', because if everything is black, then all ravens are black 20:57, 18 November 2016 (UTC)31.49.112.6 (talk)

It doesn't say all non ravens are not black but all not black things aren't ravens. Completely different. WikipediaUserCalledChris (talk) 15:07, 18 December 2016 (UTC)

The definition of evidence

This paradox is all about what the meaning of evidence is or how it should be defined.

The simplest way to define evidence is to set the divide at the limit. Any observable that doesn't contradict the assertion is evidence or information in support of the assertion. By this definition if I observe I'm hungry, then this doesn't contradict that all ravens are black and so it is therefore evidence that all ravens are black. But assignment of meaning is by our arbitrary choice and there is no necessity to define evidence this way. It can be defined any way we want to by arbitrary choice as long as we don't contradict the definition of truth itself. Truth is what's observed. Don't say you observed something if you didn't and don't say you didn't observe something if you did. This is the only actual constraint when defining meaning.

There is an unfortunate problem with defining evidence at the limit this way. If I observe I'm hungry, then this doesn't contradict the assertion that all ravens aren't black. So it is evidence that all ravens aren't black also. Now if we observe a black raven, then this would be evidence that all ravens are black. But it is also evidence that all ravens aren't black because it doesn't contradict the possibility of a non-black raven. The definition of evidence we made here doesn't seem to be to useful.

— Preceding unsigned comment added by 2603:3024:204:B00:8D04:2B05:8F0B:E5FD (talk) 16:13, 2 November 2018 (UTC) 

Nicod's Criterion

  Can we have Nicod's criterion fully specified in the article where it is first mentioned? It is absolutely critical to the rest of the exposition but it looks like you have to go to primary sources to find it (the linked article on Nicod doesn't have it either).  — Preceding unsigned comment added by Thesilverbail (talk • contribs) 17:13, 21 February 2020 (UTC)