The events of a Currency Systems.  The basic structure contains two Agent and a quanta of value transferred between them.  The value of a currency system is in its ability to create some separation between the transfer of value in one direction and the resolution of any debt of obligation created in the transaction.  For the purpose of managing a complex web of obligations, when value is transferred in one direction, a coresponding financial instrament is transferred in the other direction.  You buy something, you get the something, and you give payment.  The payment could be cash or a banking card payment that lowers my positive balance or increases my debt to the bank or store.

On the other hand, there are other kinds of transactions.  When we speak of a gift economy, what is different about its transactions and financial instraments?  The main difference is scarcity.  My ability to pay is limited either by the cash in my pocket, or a set of balances and limits maintained by the banking system.  As long as the bank judges that I have the ability to pay, or assets to sieze if I don't, they will approve my credit transaction.  If I actually have more assets than liabilities, I can always sell somthing, the more liquid the better.

A gift economy is different.  In a gift economy we understand that the common wealth is based on maintaining the productivity of a lot of assets that are held in common.  The air and water come to mind immediately, but the financial systems themselves are extremely valuable to all of us.  To the extent that individual actors make it unstable or create market failure for their own profit, they are not participating in the market, they attack it and are a danger to all of us.

We don't actually know what the financial instraments of a gift economy would look like.  In the current system, if I devote my career to a calling, how will I be secure in my later years?  If we have gift currencies, my work can be acknowledge with them, and so can lots of people who are just helping each other out.  People who care for us and our loved ones when they are unable to care for themselves can be paid in a similar way even when there is no funding in scarce currency terms.  In the current scarcity based system, those jobs pay less than minimum wage, and there are many with capacity to give service who are unemployed or underemployed.  In other words, there is abundant supply of help, skilled and unskilled, but there is no currency to pay for the service.

The downside of a gift economy is that takers can ruin it for everyone.  That's why we need a financial system, it will identify the takers.  More likely the visibility of everyones individual giving index will generally encourage more gifts of service.  Nobody wants to be a dead-beat, and the few who lack the capacity to return value for value are not a problem in the context of abundance.  The free rider problem isn't to be ignored, but by making it visible it can be addressed.  It is a design problem for the currency system to address systematically if it becomes a problem.