Indeed, I don't count unsubstantiated claims as evidence. Neither should you, unless you enjoy being Pascal-mugged.

I take ubsubstantiated claims as evidence. I take damn near everything as evidence. Depending on the context the unsubstantiated claims may count for or against the conclusion they are intended to support.

In fact, sometimes I count substantiated claims as evidence against the conclusion they support (because given the motivation of the persuader I expected them to be able to come up with better evidence if it were available.)

Indeed, I don't count unsubstantiated claims as evidence. Neither should you, unless you enjoy being Pascal-mugged.

That doesn't seem to be a response to above. Even in absence of "claims", probabilities should not equal 0. If you have an algorithm for updating probabilities of 0 that plays nice with everything else about probability, I'd be interested to see it.