Proportionality of Evidence

[jposamen]

Carl Sagan has been quoted to say, "Extraordinary claims require extraordinary evidence." Generalizing this idea, I think it's widely accepted that the rigor or extent of evidence should be proportional to the extraordinariness of the claim it supports. What are the problems with this notion?

Thanks,
Jordan

[Nocturne]

Originally Posted by jposamen

Carl Sagan has been quoted to say, "Extraordinary claims require extraordinary evidence." Generalizing this idea, I think it's widely accepted that the rigor or extent of evidence should be proportional to the extraordinariness of the claim it supports. What are the problems with this notion?

The degree to which a claim is extraordinary depends on background knowledge. Therefore, what is an extraordinary claim for Carl Sagan may be an ordinary claim for someone else. For example, if you believe that the content of The Bible is true then the resurrection of the dead may not seem so extraordinary to you as it would to Carl Sagan, or if you lived in the 15th Century Columbus' claim that the earth was spherical may have been extraordinary, but today the same claim is anything but extraordinary. In other words, if a claim contradicts a great deal of your background knowledge then it is extraordinary, and if it is consistent with your background knowledge then it is ordinary, so extraordinariness is a function of what you already believe, not an impartial quality of a claim.

[jposamen]

I agree, Nocturne. There's a relativity of extraordinariness based on personal context. But does the claim still hold? Given that X is extraordinary for a person whom we're seeking to convince of X, should the extent of evidence to support X be proportional to X's extraordinariness?

Thanks,
Jordan

[boagie]

Hello All!!

I believe it is extreme to believe that something has occured which violates the natural laws, phyical laws. There has never been a documented case of the dead arising, the sun being brought to a stand still ect.., there is an element of fantasy which cannot be taken seriously if you have any intellectual integrity whatsoever, sometimes the clowns red nose needs to be checked to see if its really real. is it really red or is it really a nose. According to revelations 9495593 it is god's nose--you can take that to the bank!!

[Aedes]

What this boils down to is what makes a claim extraordinary.

An ORDINARY claim doesn't need a lot of evidence, because it already conforms to evidence that is consistent with our everyday experience. So if I say "I let go of a rock and it fell to the ground," that really doesn't require special evidence. I mean so what, everything else we drops falls to the ground.

An EXTRAORDINARY claim lacks this connection with our everyday experiences. Thus, we're entitled to a lot of skepticism. So if I say "I let go of a rock and it transformed into a white dove and flew away," then that DOES require more evidence than the first claim.

[Nocturne]

jposemen,

I think that you are correct to interpret Carl Sagan's comment that 'extraordinary claims require extraordinary evidence' as proposal for the adoption of a convention i.e. an ethical proposal. It is quite clear that someone can make a claim and believe it without any evidence whatever, and even despite contradictory evidence. Moreover, it is quite clear that the presence or absence of evidence does not make a claim true or false, since a true statement is true regardless of what evidence we have accumulated i.e. the truth or falsity of a claim is an objective property which stands independent of anything we do.

Therefore, I think the claim is best read as the ethical proposal that we ought not to believe a claim which seems to us to be extraordinary unless we have some extraordinary evidence to justify that belief. I, for one, do not agree with this proposal. I am primarily concerned with whether the claims which people make are true or false, and not whether they ought to believe them or not. In fact, I am somewhat disgusted with those who seem to be inappropriately concerned with what others are permitted to believe according to the evidence, and I find it a distraction from the far more interesting issue of whether the claims being made are true or false.

[boagie]

Nocturne,

As a society we had better be concern what our fellow citizens believe, it would be socially irresponsiable not to care if they believe in the end times and you are at war.

"The truth or falsity of a claim is an objective property which stands independent of anything we do." quote

Truth is not an objective property, if so truth would belong to object, it does not, truth is the property of a subject, and is discerned by a subject about the relation between itself and object. As all meaning is the property of a subject, truth as a meaning, belongs to a subject.

[Nocturne]

boagie,

If the Bible is true then there has been a documented case of the dead arising and the sun being brought to a halt, and these events must therefore happen in occurence with natural laws. In other words, to believe in such occurences is extreme only because you do not already agree that such occurences could occur, and even state that they violate natural laws. The issue at hand in such a disagreement is the universe and the laws which govern it, and so your objection simply rests on the assumption that the other claim is false. If the universe does not operate as you think then these events might not seem to be so extreme, and it might be you who is in the wrong.

[boagie]

Nocturne,

Yes, if my reason and my senses were totally unreliable and proven as such, I would have to consider a chocolate universe, or any other absurdity that could be imagined.

[Nocturne]

Aedes,

You state that 'an ordinary claim does not need a lot of evidence because it already consistent with the evidence'. However, so long as an extraordinary claim does not contradict the evidence then it must also be consistent with the evidence, and so any evidence which supports an ordinary claim must also support an extraordinary claim (assuming that evidental support is had only by its consistency with a claim).