I like to think that its entirely dependent on what
you and I think its worth.
Think of it this way: even if the dollar were backed by gold and say you could get 1 gram of gold for every dollar what is 1 gram of gold worth? If I went to a store and said "I'd like to purchase 10 grams of gold's worth of cookies" what determines how many cookies the clerk sells me? It all comes back to the perception the consumer. What can the store get (paying its employees purchasing more goods to sell distributing profit to its shareholders ???) out of my 10 grams of gold should determine how many cookies they're willing to part with.
The point of currency should be 1 degree of abstraction from a barter system. I'm sure there are other reasons that my brother and other smarty pantses will point out but that's the heart of currency.
Have you ever seen
Phenomenon?
I'll quote a
site that i searched for to find the details of the barter:
"Remember the movie Phenomenon? You know the one with John Travolta. In the movie he was an auto mechanic that needed solar panels installed on his roof. He conjured up a barter to fix the car of a man that digs wells. The well digger dug a well for a guy that knew how to install solar panels and wha-la all three parties got what they wanted and it did not cost them a dime."
Each party determined that the service provided to them was worth the service they provided to the next guy. It feels like I'm rambling here because I haven't really distilled my views on economicness and the exchange of goods and services.. but I hope at least someone gets what I'm trying to say.