J.W. Wartick wrote a nice article questioning the truth of this maxim. He notes that on first blush the maxim seems obviously true, but upon further reflection it can be shown to be obviously false. Consider the claim that I am a giant pink salamander. This is an extraordinary claim, and yet the claim could be evidenced in rather ordinary ways. For example, one could come to my home and observe me. If I appear to be a giant pink salamander (one who talks and types), then the extraordinary claim is justified.
If one is not convinced by their eyes, then perhaps they could take a DNA sample and compare it to other salamanders. Such evidence is ordinary, but sufficient to verify the rather extraordinary claim that I am a pink salamander. It is false, then, that extraordinary claims require extraordinary evidence. All that is required to justify an extraordinary claim is sufficient evidence.
Wartick notes some other problems with the maxim as well:
- It is ambiguous regarding what qualifies a claim as “extraordinary.” Does it mean improbable? If so, then many events are extraordinary (yesterday’s lottery numbers, a hole-in-one, etc.)The atheist should not be allowed to get away with labeling a claim as “extraordinary” (and thus raising the bar for its justification) unless he has a clearly defined criteria for what qualifies as an extraordinary claim and can demonstrate that the claim in question meets that criteria.
- It is ambiguous regarding what constitutes “extraordinary evidence.” Is it the number of evidences, or the persuasive power of the evidence? While it is clear that the epistemic bar has been raised, it is not clear as to how high it has been raised, or how it can be cleared. The ambiguity allows the atheist to dismiss any kind/amount of evidence the Christian theist presents as “not good enough.” Only if “extraordinary evidence” is quantified can it be determined if the epistemic bar is appropriate, or if it has been met.
Wartick speculates that what people mean by “extraordinary claims” is a claim regarding things that “can’t be observed in the usual fashion” or things that have “great existential import” to our lives. In regards to things that can’t be observed in the usual fashion, Wartick argues that we do not need extraordinary evidence to justify such claims, but a different kind of evidence (logical, philosophical) than we would employ for things we observe in a usual fashion.
In regards to things that have great existential import to us, Wartick takes a cue from William Lane Craig to argue that such claims should cause us to be more open to every piece of evidence in its favor than we normally would be for things that have little existential import. Citing Craig, he provides the following example: “[S]uppose you are diagnosed with a fatal disease and there was ‘some experimental evidence that a vaccine… might cure you, wouldn’t you be desperate to [try the medicine and] find out if that might save your life… rather than saying, ‘Well, this is such a life-changing situation that I’m going to be as skeptical as I can, and only take this medicine as a last resort when it’s been demonstrated absolutely that’ it will cure the disease.”
Let me finish with a possible tactical approach to responding to this maxim. When someone says, “Extraordinary claims require extraordinary evidence,” respond by saying, “That is quite an extraordinary claim you just made. Do you have extraordinary evidence that justifies it?” Surely your opponent will object to your classification of the maxim as an extraordinary claim, but to show why it is not an extraordinary claim he will have to clearly define the criteria for what constitutes an extraordinary claim.
At that point you can debate the criteria and/or whether or not those criteria truly apply to the issue at hand (God’s existence, resurrection of Jesus, etc.). You could also respond by asking, “Why think extraordinary claims require extraordinary evidence?” This will require him to justify the veracity of the maxim, and in the process give you a chance to expose its flaws. Perhaps you could even follow up by asking, “Why think extraordinary claims require anything more than sufficient evidence?”
I recommend that you read the article for yourself. It’s a short read.