I think that both Matt and Kevin are right, although Matt did not defend his point in his initial post. The issue, it seems to me, is one of the evolution of fiat currency, not of its use. Kevin is right because children today learn to use their respective fiat currencies just as the capuchin monkeys did. The currency becomes a symbol to the individual that represents a projected consequence of using the currency. Matt is also right because monkeys did not invent fiat money. Humans did. And for them, the first users for the most part, and the second users almost certainly, associated liabilities with its use. This reasoning, by the way, is an application of the so-called regression theorem introduced by Mises. The means of introducing money are discussed by Mises at: http://www.econlib.org/library/Mises/msTContents.html See chapter 16. The reasoning of the regression theorem is also discussed by Mises. http://www.econlib.org/library/Mises/msTContents.html See Part 4. Pat Gunning