One would be Gresham's Law where "Bad money drives out good", in that all the world's fiat (the bad money) drives the good money into hiding.
I am not an economist or philosopher but I will be bold enough to disagree with Gresham on this one. If the above postulate was indeed true then we all would be using Zimbabwe dollars and I would be filthy reach because I have 100 000 000 000 000 Zimbabwe dollar bank note pinned on my cork board.
If I am mistaken and misunderstand things, please explain how.