In the larger epistemological sense, what role does the law of witnesses, e.g. Federal Rules of Evidence (http://www.law.cornell.edu/rules/fre/index.html#article_vi), play in our search for knowledge (and truth)? So much of our day-to-day life in modern society is based upon the law or rule of witnesses, e.g. the rule of law, scientific investigations, journalism (print and television news reports), to name just a few. And yet if we take the view of the skeptics -- and to a larger degree, much of philosophy -- nothing is really knowable (with respect to certainty). So how can so much of our daily life rest upon (be founded upon) a principle -- the law or rule of witnesses -- which may be without epistemological foundation? If there are any texts that specifically address this subject, I would appreciate references. Thanks in advance for any and all replies!