Lash, I agree the burden of prove rests with the presenter of a declaritive statement - that's simple, basic forensics. However, it strikes me your allusion to "reasonable doubt" misses the mark by a fair bit. While there is distinction to be made between "no proof" and "reasonable doubt", there also is distinction to be made between "reasonable doubt" and "strong doubt", with due consideration accorded to preponderance of evidence; that which in very many ways resembles a duck most often on closer examination turns out indeed to be a duck.
Now, though Xingu's flat declaration lacks conclusive empirical, external validation, the odds favor his proposition.
