Talks about a credit system built upon a blockchain naturally transition to talks about an identity system; otherwise, how would you prevent Sybil attacks [1]?
However, I am unsure to how the latter will be solved without a central, trusted party. What is the digital analogue of a passport or driver's license, a piece of identification that is hard to forge?
To add on to why fractional reserve will be hard to implement with cryptocurrencies, another unexplained problem is the issue of collateral backed by a volatile asset.
If that underlying asset rises in value, then the effective interest rate would be equal to the original interest rate + % increase in value; if the opposite occurs, a decrease in value, the 'bank' in this scenario might lose money on that lend.
You might argue that a digital stable-coin is a possible solution. But a digital asset backed by a physical object is probably bound to encounter regulations; and the performance of a stable-coin backed by algorithms is currently unknown to work.
These are two hard problems that have to be solve before fractional reserve is viable on a blockchain.
Okay, I think I see where the misunderstanding is. I'm not imagining an on-chain and fully decentralized solution. You're right that that sounds difficult.
I'm imagining a contract with a bank. As in, you literally go and talk to Chase bank and draw up a contract and give them Bitcoin and they promise to give it back to you later plus interest.
Such a system is very possible today, and in that sense Bitcoin _does_ support fractional reserve. Fractional reserve is not a feature you explicitly add, it's an emergent property of a banking system, you really don't need to do very much to "support" it.
I'm with you so far, but the bit I don't understand is that for bitcoin to be said to support fractional reserve, don't you need to have the balance of your loan issued in bitcoin as well, so that you can pay other people for services in bitcoin, and they can use that to get a new loan etc? It doesn't seem fair to say that bitcoin works for a given purpose, if "working" presumes the presence of a trusted fiat money system?
It's true that today you would probably find it difficult to find someone who will take your Bitcoin and pay you Bitcoin-denominated interest with it. However, there's no fundamental reason why it couldn't happen.
The process is: You give your Bitcoin to a bank. It is put into a UTXO which they control, and you don't control. In exchange, you have a balance in the bank which you can withdraw when you choose. Your balance is "virtual bitcoin", but is still real money, because it represents your ability to ask the bank to pay people for things. (By swiping your debit card)
At the same time, the bank has the original on-chain Bitcoin, and is free to use it however it wants, probably by lending it out to somebody else.
In this way, there is now more Bitcoin than there were previously. Fiat currency is not involved in any way. I'm not an economist, but I'm pretty sure it's exactly the same as the difference between M0 and M1.
However, I am unsure to how the latter will be solved without a central, trusted party. What is the digital analogue of a passport or driver's license, a piece of identification that is hard to forge?
To add on to why fractional reserve will be hard to implement with cryptocurrencies, another unexplained problem is the issue of collateral backed by a volatile asset.
If that underlying asset rises in value, then the effective interest rate would be equal to the original interest rate + % increase in value; if the opposite occurs, a decrease in value, the 'bank' in this scenario might lose money on that lend.
You might argue that a digital stable-coin is a possible solution. But a digital asset backed by a physical object is probably bound to encounter regulations; and the performance of a stable-coin backed by algorithms is currently unknown to work.
These are two hard problems that have to be solve before fractional reserve is viable on a blockchain.
[1] https://en.wikipedia.org/wiki/Sybil_attack