carl-sagan I can state without any sense of reservation that I really admired Carl Sagan as a popularizer of science. I miss him terribly and still cherish his remarkable legacy. The television series Cosmos, which he co-wrote with Ann Druyan, ignited my endless fascination with cosmology and astrophysics. Three of his books—Broca’s Brain, Pale Blue Dot, and Contact—are among the most tattered books on my shelf because I have read them so many times, and the latter still remains one of my favourite science fiction novels. (Even though the 1996 movie was really good, it just could not compare since, for obvious reasons, the book was able to explore nuances and depths that no movie ever could. And the plot device he turned π into? Pure genius!)

But his dictum that “extraordinary claims require extraordinary evidence” has come to irritate me something fierce, for no other reason than it ended up getting hijacked by parochial sycophants who are so remarkably irresponsible with it. It is inordinately popular with atheists because it feels in their hands like an impenetrable firewall shielding them against any and all theistic claims, but they wield the dictum horribly oblivious to a crucial handicap: they never bother to define univocal criteria for either what an extraordinary claim is or what extraordinary evidence looks like. The former is usually embellished with synonyms that never amount to a defining criterion, while the latter often gets positioned as anything that will not admit the supernatural. (For example, they usually posit circumstances or phenomena that never preclude possible natural explanations—e.g., God rearranging the stars to spell his name—being fenced in by Clarke’s Third Law on one side and Occam’s Razor on the other, for the evidence is always restricted to the empirical.) But also irritating is the audacious conceit of their demand, as if somehow their own intellectual sanction is a necessary instrument of validation for whatever claim was aired in their presence. “Without sufficient evidence to support your claim,” they usually say, “I am not able to believe it.” That may well be the case but, not to put too fine a point on it, what makes you think your belief is relevant or even required?

It is like the ghost story mentioned by Jacqueline Lavache in her article, which she has also invoked in conversations elsewhere as an illustration of an extraordinary claim requiring extraordinary evidence. Yet has either Lavache or those who make a fetish of Sagan’s dictum thought this through? If I tell a friend about an encounter with a ghost, exactly what relevance does their personal belief have to the facts of my experience? Precisely none, so far as I can tell. Surely they are not so presumptuous as to think that nothing shall be deemed a fact until it has received their personal approbation. The problems with such a stance are legion and obvious. If I share with them the facts of my experience and they are unable to believe it themselves, what relevance does that have to the event in question? None, quite frankly. Neither the reality of the case nor the facts thereof have anything to do with their ability to believe it. Further, it is actually a logical fallacy; for someone to think that some P is not a fact because he is unable to believe it himself is to commit the argumentum ad ignorantiam fallacy (which, in this case, takes the form of an argument from personal incredulity).

The issue becomes even more salient when theistic claims are discussed. (I should like to focus the point on things I do believe, as opposed to things like ghosts which are not part of my mental furniture. I will let those who believe in ghosts do business with such issues, while I shall engage my actual convictions.) Suppose that someone overhears me stating that moral order is grounded in the very nature and character of God and expressed prescriptively in his commands, to which the person responds, “That is an extraordinary claim.” But is it? You see, I have to wonder if this person has thought the matter through. What, exactly, is the univocal criterion for indentifying a claim as extraordinary? Despite having read a wealth of atheistic literature both in print and online, from recognized scholars to armchair philosophers, and despite having engaged in countless discussions with a significant cross section of the atheist community, not once have I ever encountered a definitive univocal criterion. At minimum, atheists merely indicate one statement after another as being extraordinary, as though I am somehow supposed to guess the criterion by unearthing a common denominator. At most they simply embellish the adjective, as I said earlier, with synonyms that never amount to a criterion.

The closest thing to a univocal criterion that I have seen was given by Laurence Boyce who, in his article, determined that the criterion should be fashioned after Hume’s maxim (in which he suggests that we replace every instance of “miraculous” with “extraordinary” and the like), rendering the reading of it as follows:

No testimony is sufficient to establish [an extraordinary claim], unless the testimony be of such a kind that its falsehood would be more [extraordinary] than the fact which it endeavours to establish.

That sounds good, on the face of it, but do you notice the inherent problem? This cannot serve as a criterion at all, for it is committed to the same problem I identified earlier; namely, it is an embellishment that does not amount to a criterion. It says that some testimony (evidence) is extraordinary when its falsehood is more extraordinary than the fact (claim) which it attempts to establish; in other words, the criterion uses the very thing it is supposed to define.

Boyce also stated elsewhere, in the comments area of his article, that an extraordinary claim “is one that, among other things, contradicts claims that are already backed by extraordinary evidence.” While I wish that he had identified what those “other things” might be, this formulation is even less workable and therefore ignored; what Boyce here describes as “claims that have extraordinary evidence against them” are in fact delusions, according to medical dictionary definitions.

And throughout his entire piece Boyce makes frequent reference to the probability that one would believe that X, or that he has not asked anyone to accept X, or what it would take in order for one to accept X, or wanting people to think X is true, etc. That is, he falls prey to my aforementioned criticism: “Neither the reality of the case nor the facts thereof have anything to do with their ability to believe it.” I do not care if someone is unable to believe X, for it has no bearing on the truth of X. To think otherwise commits the logical fallacy I had identified.

So Boyce failed to establish a univocal criterion for what constitutes an ‘extraordinary’ claim, and his description of evidence was less ‘extraordinary’ than ‘sufficient’. As my friend Martin Pate indicated (one of very few intelligent atheists I have been fortunate enough to meet), “Sagan’s dictum makes it sound like any claim which violates widely subscribed beliefs or received wisdom automatically is at an evidentiary disadvantage. This is simply prejudicial,” which he juxtaposes against probative value.

So the next time you hear someone say, “Extraordinary claims require extraordinary evidence,” confront that assertion head-on. You are well within the epistemic right to ask what he even means; and in all likelihood, he does not himself know, but is rather just parroting a dictum he has made a fetish of without ever giving it serious thought. There are three things you want to know: (1) What is an ‘extraordinary claim’, and what is ‘extraordinary evidence’? (2) Specifically, what is the univocal criterion for establishing either? (3) What does their ability to believe that some X is true have to do with whether or not X is actually true?

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