If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… > On Jun 19, 2015, at 9:36 AM, Matt Whitlock wrote: > > On Friday, 19 June 2015, at 3:53 pm, justusranvier@riseup.net wrote: >> I'd also like to note that "prima facie" doesn't mean "always", it means >> that "the default assumption, unless proven otherwise." > > Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend.