JurgenBM

That idea would justify an argument like: "That claim is not considered by many people to be outrageous, so it's true." or "That claim is considered by many people to be outrageous, so it's false." but that's just a variant of the argumentum ad populum; Logic doesn't work that way.

Stephen T-B

"Logic doesn't work that way." (JurgenBM)

I think in the real world there's rather little logic.
But that's not really the point.

A mathematician claims to have proved Fermat's Last Theorem.
Does he have to prove it?

Another mathematician comes along and says "No you did not?"

Does he have to prove that?

JurgenBM

If you say "I don't believe in ghosts because the theory of ghosts is not an accepted scientific theory." it's a reasonable argument and you're not evading the burden of proof this way.

If you say "I don't believe in ghosts and I don't need to defend it since ghosts are not an accepted scientific theory." it's an unreasonable argument because you're making excuses to evade the burden of proof. Any way of immunizing your argument against criticism is unreasonable.

Roq

In practice you are right. When I go to visit my family at Christmas and try to make a claim such as that homeopathy could not possibly work because the dilution levels mean that there’s unlikely to be any molecule of the remedy in the solution, the burden of proof is definitely on me. After all Mavis down the road had a wart and…

I think though that science provides a consensus position because it’s demonstrably the only system of gaining knowledge that can be seen to work. So the most rational position to take is that science shifts the burden of proof onto the side that is making a claim not encompassed by current scientific theory.

Roq

I don’t see what you are getting at here. Surely I can say: “I don’t believe the universe was created by a fish living on the moon and I don’t need to defend my position because there is no evidence that fish live on the moon”. This evades the burden of proof, but seems entirely reasonable to me. Nor is such an argument immunized by avoiding the burden of proof…

JurgenBM

Logic is a study, it is man-made and not inherent to reality in the first place.
He'd have to argue that "It is impossible to separate any power higher than the second into two like powers".
I think "No you did not?" is an expression of disbelief. If the second mathmetician actually would have said "It is not impossible to separate any power higher than the second into two like powers." he would have needed to come up with arguments.

JurgenBM

I'll tell you what the difference is: No one is going to disagree with you that the universe was not created by a fish living on the moon, so you don't need to argue about it. Technically it would be unreasonable if you evaded the burden of proof and why would you? You could just skip the "and I don't need to defend my position" and be perfectly reasonable. The point is: If no one is questioning what you're saying you don't need to defend your point of view at all. Having said that, there is no way of justifying evading the burden of proof. There are no exceptions.

Roq

It’s a thought experiment -The point was that someone might be claiming it. What if there were a cult of such fish worshippers? Would my statement then be unreasonable? Surely not…

JurgenBM

Two similar discussions:

A: "The universe was not created by a fish living on the moon."
B: "I'm not sure so about that."
A: "Well I'm right and I don’t need to defend my position."

X: "The universe was created by God."
Y: "I'm not sure so about that."
X: "Well I'm right and I don’t need to defend my position."

You're saying that A is being quite reasonable while X isn't, while they're doing the exact same thing: evading the burden of proof! That doesn't make sense to me. Why should there be a double standard about burden of proof? That would be unfair and unlogical. You can't draw an objective line where you say "These statements are so self-evident that they cannot be questioned and they do not need argumentation".

I'm not making this stuff up by the way, this is just part of the pragma-dialectic approach to argumentation.

Roq

The question being asked in this thread is about determining which side has the burden of proof. Why should we care? Well if we can find a process for allocating a burden of proof that rarely fails to elimate correct results it reduces the amount of work we have to do to a manageable amount. Scientists could not operate effectively if they felt that they had to show that every cock eyed idea was false:- There are literally an infinite number of claims that it is possible to make about the world.

Taking the above into account we can rephrase your first dialogue as follows:

B "The universe was created by a fish living on the moon."
A: "What evidence can you provide for that"
B: “I have no evidence, but the burden of proof is on you”
A: "I don’t have time to evaluate propositions that are unsupported by evidence – and extraordinary claims require extraordinary evidence. So its your move."

Now A’s position isn’t unreasonable is it?

Sounds impressive