Extraordinary Claim, Extraordinary Evidence?

Do extraordinary claims demand extraordinary evidence?

Hume offered this challenge in "Of Miracles" in Dialogues Concerning Natural Religion.

This requirement is offered in response to the miracle claims of Christianity as though it’s an obvious, well-established principle.  But it’s actually not clear what the criteria of "extraordinary evidence" is, and here are three lines of response.  These are rebuttals, calling into question the principle in the requirement, rather than refutations because the challenge itself has to be supported by an argument and clarified for the nature of what is being required.

First, there needs to be a clarification.  The nature of the “extraordinary evidence” required can be understood in two ways: extraordinary with respect to quality or extraordinary with respect to quantity.

If the former (quality), then the evidence produced is itself extraordinary, and it will also need to meet the requirement of having extraordinary evidence, and a vicious regress ensues.  If the quality of evidence for an extraordinary claim must be also be extraordinary in quality, then it will also have to have extraordinary evidence.  But then the condition can never be met, and suffers from the fallacy of “begging the question” against extraordinary events in an unfair manner.  The game is rigged by the request.

And perhaps that is the point of the requirement because it presupposes naturalism, precluding the possibility of offering evidence that will justify a supernatural claim.

If the requirement is for an extraordinary quantity of evidence, then the next question is, how much ordinary evidence is necessary for the total quantity to be considered extraordinary?  This is perhaps a “problem of heaps” – how much is enough?  There is no determinate solution (at least epistemically, if not metaphysically determinate).  So once again, it’s begging the question to ask for extraordinary evidence.

An alternative for answering the question of sufficient quantity of evidence would be to allow that there is some amount of evidence sufficient for establishing the probability of an ordinary event.  But then, the fact that we find a certain multiple of the ordinary amount of evidence sufficiently extraordinary is either a case of evidential over-determination or is itself an extraordinary event, and once again leads to an infinite regress.

A third response to the demand recognizes that very extraordinary events happen all the time if the co-occurrence of several features in a state of affairs is evaluated probabilistically.  (That an American high school kid from Seattle would be at a Halloween party in Tel Aviv and there meet an American high school girl from Pensacola and later marry her is highly improbable; in fact, the people I know who this is true of might be the only two people in all of history who fulfill that concurrence of events.) 

So no matter how extraordinary the event, no explanation is needed because extraordinary events happen all the time.

(Thanks to Dr. Garry Deweese, Biola University, for this line of response.)

Comments

[Johnnie]

I think that the amount of evidence needed is an amount needed to surmount the evidence presented by the other side. Think of the scales that represent Justice. It's not the absolute amount, it's who has the better evidence.

In English/American jurisprudence, the standard of evidence needed to prevail is based on the type of claim: rebuttable presumption, probable cause, preponderance of the evidence, clear and convincing proof, proof beyond a reasonable doubt.

[EpistletotheApostles]

Ridiculous hand waving. The well established principle is that if you make a claim you need to back it up with evidence.

"So no matter how extraordinary the event, no explanation is needed because extraordinary events happen all the time."

Precisely - no need to invoke any deities here thank you. What you deem as 'extraordinary' can be rationally explained, and actually isnt extraordinary but any objective measure.

Lets bring this back to earth with some examples. Mind reading or spiritulist mediums. Lots of people believe this trickery despite the fact that people like Derren Brown do exactly this sort of thing and show how they do it without any supernatural intervention. So if someone comes along and says "I can talk to the dead/read your mind", what evidence would you like to see before you accept that claim as true?

The existence of a deity is a hypothesis, exactly the same as string theory/evolution/gravitation. So stump up some evidence and stop flapping about the circumference with sematic clap trap about whether that evidence is extraordinary enough. Just 'some evidence' would do for starters.

[topher]

"So no matter how extraordinary the event, no explanation is needed because extraordinary events happen all the time."

Exactly, Joseph Smith found and translated, with the help of god,gold plates. 11 people signed documents claiming they had seen them. See extraodinary claims happen all the time, why don't you believe this one?

[Patrick H]

"The well established principle is that if you make a claim you need to back it up with evidence."

I would not disagree with the statement quoted above. But what is the basis of this well established principal? You claim that claims must be backed up by evidence. What evidence do you use to back up that claim?

[kpolo]

Topher,
You surely are smarter than to ask such a question. No one is saying that events don't need any explanation or that the explanation should not be coherent.

In Joseph Smith's case, he claims extra-biblical revelation when the epistles in the NT declare the cannon complete. With the coming of Christ, God revealed all he needed for salvation and future judgement. Joseph Smith's revelatory claims was not only redundant but also contradictory to the prior revelation in the Bible.

[SteveK]

In summary: Extraordinary claims require sufficient evidence, and no more than that.

[Jon]

Melinda, you write:

If the former (quality), then the evidence produced is itself extraordinary, and it will also need to meet the requirement of having extraordinary evidence, and a vicious regress ensues.

You're taking "extraordinary evidence" to be "evidence that is extraordinarily unlikely to come about." That's not what is referred to. What Hume is doing is basically expressing a simplified expression of Bayes Theorem. So it's not that the evidence is unlikely to come about but that it is the sort of evidence that rarely leads to false conclusions. Eyesight would be extraordinary evidence. If I saw a space alien I might be inclined to think they exist. On the other hand my eyesight can fail me so I'm not 100% certain. If I told someone I saw a space alien their evidence is not my eyesight, but my claim, which from their perspective is not extraordinary evidence. Though it's often good enough it wouldn't be in this case.

i>A third response to the demand recognizes that very extraordinary events happen all the time if the co-occurrence of several features in a state of affairs is evaluated probabilistically.

Bayes Theorem, which is basically what Hume is describing, fully accounts for this. It's generally true that extraordinary claims require extraordinary evidence. But technically there is another factor in Bayes Theorem that Hume hasn't described. What is the likelihood that the evidence would be produced if the claim was false?

So let's say a lottery # is chosen. Any particular # is extraordinarily improbable. So if the paper reports that the winning #'s are 34, 53, 85, 12, 39, then would a person that thinks it's generally true that extraordinary claims require extraordinary evidence believe it? The answer is yes. While those particular numbers are improbable it's even more improbable that the paper would report those particular #'s if the claim was false.

Hume's claim is generally true. If I tell you that I saw spaghettio's turn in to bunny rabbits you'd dismiss my claim without exceptional evidence (video recording, maybe even reproducing the event in front of you or in front of selected witnesses, etc). The resurrection of Jesus is a similar type of claim and thus requires a similar type of evidence.

[Joe]

"Extraordinary claims require sufficient evidence, and no more than that."

Let's say that you're walking down the street, and you see a man floating three feet off the pavement. You ask him what's going on, and he tells you that he's a magician who can create the illusion of levitation. He says that gravity is still affecting his body, he's not really floating, but he does know how to make it look like gravity has been suspended. In this case, how much more evidence do you need before you accept his claims? What is sufficient evidence for the claim? Do we really need any more evidence in this case?

Now let's say that you see a man floating, and he says that he has prayed to Ahman-Ra and Ahman-Ra has suspended gravity for him, and he is free of the force of gravity, and so he can float above the pavement as if he had no mass. What would you accept as "sufficient" evidence for this claim? Would you want more evidence before you accepted the claim? Would you want more evidence then you'd want in the case of the first floater's claims?

[RonH]

I think this goes with what Jon said. In the saying, extraordinary claims require extraordinary evidence, the word extra extraordinary is used in two ways. Referring to the claims it means surprising. Referring to the evidence it means strong. This doesn't suggest an infinite regress.

And perhaps that is the point of the requirement because it presupposes naturalism, precluding the possibility of offering evidence that will justify a supernatural claim.

Actually, it doesn't even distinguish between natural and supernatural claims. Suppose I tell you I set the world record for the 100 meter sprint yesterday. If you know what I look like you will want more than my word for it. Believe me.

Here's some evidence that, given evidence, skeptics are willing to accept supernatural claims:

JREF $1,000,000 challange

SteveK,
Joe's right isn't he? You'll take my word for some claims as sufficient. For other claims, you want confirmation. The more unlikely my claim seems to you, the 'more' confirmation it takes to get you to sufficient.

RonH

[Louis Kuhelj]

Extraordinary evidence just might not be sufficient for some and what might be sufficient for one person might not be sufficient for another. For some claims no evidence will ever be sufficient because they are predisposed to disbelieve the claim regardless of sufficiency or extraordinary nature of the evidence. The nature of the evidence is not a determinant of a person's response to it. It is the nature of the person that is.