What are the merits/demerits of establishing this policy?

Since fiat currency is so vulnerable to being manipulated for political purposes and relies heavily upon the goodwill and priorities of its holder, why exactly are we not reviving the gold standard? Or even better, why are we not adopting a monetary policy of having the dollar circulation quantity based upon this ratio: 25% the market value of platinum, 25% the market value of gold, 25% the market value of silver, and 25% of the international currency market value? What are the pluses and minuses of that? More importantly, how can I get the Washington Columbia District to see the light and give this some serious thought?