Bimetallism was fundamentally unworkable because it presupposed a fixed ratio between gold and silver that didn't account for changes in their respective market values. In any case, both metals were pegged to the U.S. Dollar, which was the currency. There were no competing currencies, but rather the fiction of bimetallism.
If you are seriously proposing bimetallism as a workable system in the year 2012, you are a total and complete kook and have no business discussing the matter because you clearly have no fucking idea what you are talking about.
You made a blanket statement that multiple-basis currencies cannot and haven't existed.
I showed two counterexamples.
I'm not sufficiently versed in contemporary currency matters to discuss the feasibility or actuality of significant currency bases presently. But that wasn't the question.
With regards to governments deciding on currencies: it's not that alternate payment methods cannot be considered. It's that a payment in the legal tender for a debt cannot be refused (without prior arrangement) without voiding the debt. If you make a credible offer to pay in legal tender and the payee refuses, the debt is void. Doesn't mean you can't make payment in gold or cowrie shells, so long as you both agree to that. Including to the IRS (e.g.: property seizures to pay back taxes).
> You made a blanket statement that multiple-basis currencies cannot and haven't existed
No, I said that there's no such thing as competing currencies. Having a single currency with more than one base has obviously been tried, but it didn't work.
> it's not that alternate payment methods cannot be considered. It's that a payment in the legal tender for a debt cannot be refused (without prior arrangement) without voiding the debt
Right. It just so happens that this provides enough of a nudge for the entire currency base to switch over to the legal tender currency.
> e.g.: property seizures to pay back taxes
I never thought of that as an alternative form of payment. Heh. It's clearly a bit of a corner case, and at any rate, if I own a house, that's not really a commodity I can use as a medium of exchange, even if the IRS can seize it or my bank can foreclose on it.
>> You made a blanket statement that multiple-basis currencies cannot and haven't existed
> No, I said that there's no such thing as competing currencies. Having a single currency with more than one base has obviously been tried, but it didn't work.
I still say flat out that you're mistaken. We have (and have had) multiple currencies in the world, used within a single area (quite often, especially during wartime), regionally, and worldwide. How do you deal with multiple currencies? Via exchange rates. These may be floated or decreed, but they exist. Dollars, Euros, Yen, and gold are all commonly used for current-day international transactions (with a strong preference generally for US dollars, though this may change). The dollar also has special standing as the preferred reserve currency, but again, this is largely a matter of convention, liquidity, and stability.
Over historical time, there have been (usually local and smaller-scale, though not always) systems in which multiple currencies managed by multiple sovereigns circulated and were commonly used. Sometimes usage is specific to transaction types (e.g.: use currency A for large and multi-region transactions, use B generally for local/smaller transactions).
On England's tri-metalism, Adam Smith discusses this at length in On the Wealth of Nations. The standards date to Roman times (copper basis), with silver emerging from the Saxon tribes, and gold from mainland Europe.
If you are seriously proposing bimetallism as a workable system in the year 2012, you are a total and complete kook and have no business discussing the matter because you clearly have no fucking idea what you are talking about.