The Raven Paradox - Can anyone explain this in layman's terms?

Alright. Let’s forget inductive logic, then, and just investigate the notion of evidence. Is there any evidence which falls short of infallible proof? If so, what would be an example?

Well, say there’s a raven on the desk in front of me. I look at it, and to me it looks black. That would be evidence that that raven was black, but far from infallible proof.

This started as a factual question about a specific philosophical paradox, which was perfect for General Questions. It has become a more general philosophical discussion and debate about the philosophy of science, which belongs in Great Debates. I’ll move it there.

Gfactor
General Questions Moderator

Depending on what it means to be black, that could be infallible: perhaps being black is, by definition, simply the same thing as appearing black. In which case, a raven appearing black means, tautologically, that beyond any room for error, the raven is black.

But since you take this to be merely fallible proof, I suppose you have some other, external criterion of genuine blackness (perhaps absorbing photons in a particular way or what have you). [You perhaps also have external criteria for the raven to even exist to possess the property of blackness, etc.]. In which case, this being evidence would appear to depend strongly on a promise such as “Things which look black to me actually are black”. Is this premise held up by full evidence itself? It is not apparent to me that it is in any better a foundational position than the kinds of premises you bar from evidentiary use.

Er, not “promise”, but “premise”. Though there is a kind of poetic connection…

That’s true. All things considered, it’d probably be best to have a “What most humans see as black” measure, but we can’t actually do that, alas.

I would say that probably my metric of blackness would be “Does it seem black to me when I have my normal sight?”, normal being in terms of what I appear to see like most of the time. So it’s really a pretty internal measure, for the lack of a good external one. I’m not really sure that has any premise upon which it is based; it pretty much starts of there, really; “Things that look black to me look black to me” is somewhat self-fulfilling.

Well, building on that and trying to understand it as fallible evidence, perhaps we should understand “The raven is actually black” as meaning “The raven will look black to me most of the time”, so that fallibility would be exemplified by the situation where later observations consistently showed the raven to be white. In this case, the raven appearing black being evidence for the raven actually being black would seem to depend on the premise that “Whatsoever looks black to me now will tend to continue to look black to me consistently in the future.” This seems very similar to the inductive premises which you reject for evidence, however.

It looking black now doesn’t mean it won’t necessarily in the future. I take the fallibility of the statement as being a fallibility of understanding; perhaps it’s too dark for me to be able to see well, perhaps i’m dreaming and there’s no raven at all, perhaps i’ve not realised i’ve left my sunglasses on, and so forth. If the premise relies on me seeing it with normal sight, them there’s two points it can fail on; that i’m actually seeing it, and that I have my normal sight.

I guess my general question is, suppose evidence E for claim H is fallible; when (not necessarily true) conditions P hold in addition to E, then H actually is true, by force of E’s suggestion. Otherwise, H can fail, illustrating E’s potential to lead us astray. Why might we say that E is absolute evidence, then, without demanding additional evidence for the truth of the conditions P which enable for E its force?

In this particular case, where E is the appearance of a black raven and H is the raven actually being black, presumably P will be such things as “I am not hallucinating or behind tinted glass or…”. Why is this acceptable as a foundation on which to ground evidence where inductive premises were not?

If “I am not hallucinating…” is to be supported by further evidence, and that in turn by further evidence, either we have an infinite regress (presumably unacceptable, with support necessarily being well-founded) or we must bottom out somewhere: what kind of premises are acceptable at the bottom and what kind are not?

It depends on whether E is as fully evidenced by P as P itself is. In this particular case, P I would accept as evidence, because it speaks to the whole of the claim - this is assuming you’re counting P as all of those things put together. Likewise, E in this case is also evidence, because it speaks to the whole of the claim of the raven being black. But E would not be evidence if the claim was that all ravens are black, because it provides no effectual support.

Any kind of premises are acceptable anywhere. Premises for which evidence building off of it would be what i’d call evidence requires only that there is at least some evidence that speaks to the whole of the claim. “I am not hallucinating…” is supported by the evidence that I don’t think i’m hallucinating; it might not be particularly good evidence, but it does encompass the entirety of what’s being concluded from it. On the other hand, if I could only say “I *sometimes * do not think that I am hallucinating”, that doesn’t speak to the whole of the claim, and thus I wouldn’t consider it evidence.

“I am not hallucinating…” is supported by the evidence that I don’t think I’m hallucinating? [Or, slightly more, I suppose, not merely that, but also that I assertively think I’m not hallucinating, that I feel like I am in a non-hallucinatory state, etc…]

Well, alright. You admit it (“I don’t think I’m hallucinating”) is not great support, but what’s important to you is that it does encompass the entirety of what’s being concluded from it (“I am not hallucinating…”).

But if this is an acceptable kind of evidentiary support, could not any premise P be likewise supported by evidence such as “I feel like P is true”? After all, “I feel like P is true” does speak to the whole of the claim P; it’s all in there.

If so, of course, then we take P to be something like “Whatsoever is observed of many things without fail is probably true in general”; we support this with “I feel like whatsoever is observed of many things without fail is probably true in general”. Not great support, but it speaks to the whole of that claim. And then, given that (evidentiarily supported) starting point, the observation of many black ravens could serve as evidence for ravens being black in general [this observation speaking to the whole of this universal claim when taken in conjunction with the premise P which asserts precisely that connection].

Well, I would tend to say in the grand scheme of things that it isn’t great support is much more important to me than calling it evidence or not. I’d really prefer to not be hallucinating. :wink:

No, because in this particular case whether the particular claim has merit actually has a strong effect on what I think. The colour of ravens isn’t affected by what I think about something, so “I feel like all ravens are black” isn’t evidence; on the other hand, whether i’m hallucinating or not will have a strong effect on whether I can tell i’m hallucinating, and so “I feel like I am/am not hallucinating” is evidence.

Right, of course. My poor wording; I just meant, “what’s important to you in terms of figuring out what counts as evidence”.

Why do you suppose that whether or not you are hallucinating has any effect on or correlation with whether or not you think you are hallucinating? (Perhaps the relevant mechanism of hallucination is such that you routinely enter a hallucinogenic state while feeling perfectly lucid; conversely, perhaps you routinely think yourself to be hallucinating when, in fact, what you see are actually genuine images).

Ah, sorry for misunderstanding.

All of those things are certainly possible. I would argue though that (having hallucinated before, and been able to recognise that) I do at least have some ability above 50% chance to know when I am. Certainly I might not catch it all of the time, but there’s some chance I will - like I said, pretty poor evidence.

No problem.

Your argument is that, your hallucination-recognition sense having been generally accurate in the past, this serves as evidence that in the current instance as well, your hallucination-recognition sense is accurate?

It seems as though everyone is avoiding the obvious answer here.

Absent outside knowledge, the difference is merely one of scale. The set of ravens is much smaller than the set of non-black objects, so an observed black raven is more valuable than an observed non-black non-raven. No problem yet.

But we do have outside knowledge. For example, we know that a raven is an animal, and we have previously observed that members of the same species tend to share physical characteristics. When we apply this (and other) outside knowledge, an observation of a black raven becomes incomparably more valuable.

The “paradox” relies on surreptitiously using this outside knowledge. Without that knowledge, it really is just a matter of scale, and nobody would have a problem with it.

:slight_smile:

I hope you register to the site, Carmady.

Probably accurate, but yes.

Is that not precisely an inductive argument? “X has held for many instances; this serves as evidence that X will hold of other, different instances.” Take the instances to be ravens, X to be being black, voila.

Good point. I think i’ll have to revise my concept of evidence.