So if something does not provide a perfect guarantee, it's "nothing"? You realize that handwritten signatures on a paper contract do not provide a perfect guara

So if something does not provide a perfect guarantee, it's "nothing"? You realize that handwritten signatures on a paper contract do not provide a perfect guarantee either? Signatures can be forged. And the paper is not going to remain in perfect condition forever, at some point in the future the paper is going to decay. Does that mean we can never know anything about anything? No. Of course we can have evidence about events which occurred in the world, even if the evidence doesn't provide a 100% guarantee of something, indefinitely. For example, a handwritten signature on a paper can be imperfect evidence that the contract took place, or a DKIM signature on an email can be imperfect evidence that the email is not a forgery.