10 upvotes, 2 direct replies (showing 2)
View submission: Do extraordinary claims require extraordinary evidence?
On a straightforward reading, yes. The more improbable a claim is, the stronger the evidence that you (should) require in order to believe.
To illustrate, imagine two contrasting claims that your friend could make. (1) that they tossed a fair coin heads 2 times in a row; (2) that they tossed a fair coin heads 100 times in a row. The former you should probably believe on say-so, unless your friend is a habitual liar or has some reason to not tell the truth in this case. The latter, by contrast, is an "extraordinary" claim in that it has a vanishingly low probability of occurring. So you shouldn't just take their say-so on it, clearly. If they have a witness, it had better be someone that you trust and believe to be neutral---and even then, you should probably suspect that *something* was going on that rendered the coin un-fair, something that the witness couldn't or didn't identify. It's simply much more probable that something of that sort has gone wrong than that your friend tossed a hundred heads in a row.
Now, that's not to say that the only feature of a claim that matters is how extraordinary it is. You might want a lot of evidence for a very everyday occurrence because you really really care about the outcome, and you might reasonably demand only weak evidence for some extraordinary claim because it doesn't matter much to you. But all other things being equal, yes, the amount / quality of evidence that you (should) require to believe an claim is proportional to how implausible that claim is.
Comment by einst1 at 11/03/2021 at 09:48 UTC
6 upvotes, 1 direct replies
I'd say that this is a really, really, charitable reading of Sagans maxim. What is 'extraordinary' even supposed to mean here? For example, say one argues the existence of God. Presumably, Carl Sagan would like 'extraordinary' evidence for that.
Well, one could give the Kalam argument, the ontological argument, and so on. These arguments are not particularly 'extraordinary', it seems to me.
And lets say that you live in a small village in Poland, and your friend says he saw Daniël Radcliffe buying groceries. That is probably extraordinary, since he isn't a Pole, and even if he were in Poland, why in a village. Yet, a picture of him with his face would presumably suffice to prove to your friend that he was there.
If neither these claims are 'extraordinary', I find it hard to see what 'extraordinary' means, and how it relates to supposedly 'extraordinary' evidence. Perhaps one should just say that 'evidence for a claim should be sufficient evidence that supports the claim', but then that would be an empty statement.
Comment by javaxcore at 11/03/2021 at 09:23 UTC
-3 upvotes, 1 direct replies
For me it's a fallacy the problem with biggest stupidest questions is that there isn't any ordinary evidence.