the interest on the principal. The problem arises when earnings fall below that level or the interest burden rises to a point when the debt can no longer be sustained. At that point default becomes inevitable.
Paying down debt by restricting spending is fine so long as your economy is growing. The problem is that austerity programs can cause economic contraction since they essentially suck money out of circulation and pay it to lenders who may or may not lend the money out again. If that happens then earnings may fall faster than the balance of debt to be repaid so that while the amount outstanding may be smaller the actually ability to fund the interest payments has declined at an even faster pace. This is the austerity trap that Keynes spotted so brilliantly
Of course one way round this conundrum is simply not to pay the debt. In fact the current governments attempts to chisel money out of employees and the public by reneging on contractual agreements with regard to redundancy rights and pensions is precisely that type of activity. HMG are simply defaulting on their obligations. Unfortunately for our rulers just screwing the little people is no going to save our rotten financial system since the amount of private debt and malinvestment dwarfs any public sector liabilties.
Of course you will not find out any of these facts from listening to the paid hacks of the Con-Dem government who simple recycle the public spending bad/private spending good twaddle that neoliberals have been churning out for 30 years. Nonetheless there are independent economists such as the Australian Steve Keen who have done good analysis of what is really at the root of our problems
http://www.nakedcapitalism.com/2010/07/steve-keens-scary-minsky-model.htmlYou can also read more in this excellent article written by Reuters man John Kemp in 2009
http://www.reuters.com/article/idUSTRE50I4BU20090119 What we are seeing in the UK, Ireland and the USA etc is a massive fraud whereby those in the financial sector are trying to dump their debt liabilities on the taxpayer and then pretend the whole debacle had nothing to do with them. When this scam finally collapse and IT WILL BLOW UP then you are looking at economic collapse and possibly revolution