Does an extraordinary claim require extraordinary evidence?

[harvey1]

Once in a while, you get this doozy of a phrase that many people just agree with because it sounds good. However, I disagree with this statement. In fact, I would say that the extraordinary nature of a claim is only loosely related to extraordinary evidence. That is, it's possible that the evidence supporting an extraordinary claim could be extraordinary, but most of the time, the evidence is not so extraordinary.

Rather, evidence usually accumulates until it forces a paradigm shift in understanding, and it is very often the straw that breaks the camel's back that all the "extraordinary" evidence is re-interpreted in light of the new paradigm. Once the new paradigm is accepted, the former neglected evidence is seen in this new light, and the old paradigm is then seen as being very unsatisfactory to say the least.

So, since people like catch phrases, how about "drastically different paradigms in thought require enough evidence that leads to a drastic re-interpretation of all the available evidence"? Does anyone disagree and still maintain that extraordinary claims need extraordinary evidence?

[juliod]

Claims with many reasonable possibilities require elimination of those other possibilities.

After considering the issue for a while, I don't really think there is a difference between our views.

The question may come down to what is a reasonable possability, and that standard may change with the nature of the claim.

For example, for any claim or statement there are at least these constantly operating possabilities:

1) The claimant is intentionally lying.

2) The claimant is mistaken.

3) The claimant is delusional.

4) The claimant is the victim of a fraud.

For any arbitrary claim these cannot be ruled out without a detailed investigation. But for mundane claims these are not considered reasonable explanations in the absense of any reason for suspicion.

For extraordinary claims, however, it is often necessary to looks for evidence of fakery or fraud before accepting the claim. Mistakes are much more reasonable in many cases than the extrordinary claim that may be accompanied by evidence.

So, in my view, the nature and quantity of reasonable alternatives changes with the extraordinariness of the claim under question.

DanZ