That's not true. Debt is perfectly possible with a fixed currency base, and mining or grabbing transaction fees is not a substitute for debt in any way. In fact, you can have a whole expansionary currency system on top of a fixed asset like BTC, in the same way that the USD was once convertible in and out of gold.
Bitcoin is fundamentally different because new currency is created through mining. Yes, you could create a secondary market on top of Bitcoin that handles loans, but not new Bitcoins, therefore it is debt- free currency. When Nixon decided to decouple the dollar from gold in the seventies, what he did was effectively to move from a debt-free currency to a debt based currency. The move had huge implications in shaping the world until today, because it meant that the US became free to print dollars endlessly. The external market for dollars was solid because of the world reserve status, enforced through the US military. In this way the US could print away AND keep internal inflation very low in relation to the amount of circulating currency.
Breaking this cycle, which is what feeds the US empire, is why I think Bitcoin will in the end provide a great service to mankind.
Money effectively is both commodity and an IOU. Attempts to force it into one category or another eventually leads to social breakdown.
The key question for our time is how to craft a stable monetary system that is decentralized. We don't know how to do this yet, and Bitcoin is not likely the answer BECAUSE it is finite (which would be catastrophic, as gold was). Crypto currencies can and should grow in experimentation but this one has a fundamental flaw.
http://www.theguardian.com/culture/2011/dec/16/note-worthy-n...