The way I see it is, that the bitcoin economy is growing much faster than the money supply which leads to higher and higher prices for bitcoins, one can verify that by taking a look at mtgox. Also I think it's impractical for the bitcoin economy to stop growing when 21 million bitcoins are reached.
Very good point. Few people see this problem. It is absolutely necessary that money can be created at no cost whenever it is needed. If this is not possible, production can not be extended. Normally, money is created by credit. Bitcoin doesn't have this possibility. Whatever it is, it's not a functional currency.
Money is credit. When you accept USD you're giving credit to the FED, when you accept BTC, you're giving credit to the block chain. People pay higher and higher prices for BTC because they give it more credit. Credit is being transfered from other currencies to bitcoin.
BTCs, USDs and gold are just certificates that you gave something to another one.
Again, like Morgan said: "Gold is money, everything else is credit".
No, Morgan, Gold is credit too.
"Normally, money is created by credit."
Always.
"Bitcoin doesn't have this possibility."
Yes, you can create a bitcoin bank with fractional reserve, but there's no law that allows you to have a certain minimum reserve by default: you will have to convince your customers. You can even be your own zero reserve bank with ripple (denominated in bitcoins).
"It is absolutely necessary that money can be created at no cost whenever it is needed."
Creating money is not the only way to improve liquidity. I prefer demurrage for scarce currencies, and/or mutual credit money (like ripple).