For those still scratching their heads over MMT, here's a useful primer from the folks over at Naked Capitalism.
http://www.nakedcapitalism.com/2013/03/what-is-modern-monetary-theory-or-mmt.html
http://www.nakedcapitalism.com/2013/03/what-is-modern-monetary-theory-or-mmt.html
The essential insight of Modern Monetary Theory (or MMT) is that sovereign, currency-issuing countries are only constrained by real limits. They are not constrained, and cannot be constrained, by purely financial limits because, as issuers of their respective fiat-currencies, they can never run out of money. This doesnt mean that governments can spend without limit, or overspend without causing inflation, or that government should spend any sum unwisely. What it emphatically does mean is that no such sovereign government can be forced to tolerate mass unemployment because of the state of its finances no matter what that state happens to be.
Virtually all economic commentary and punditry today, whether in America, Europe or most other places, is based on ideas about the monetary system which are not merely confused they are starkly and comprehensively counter-factual. This has led to a public discourse about things like budget deficits and Treasury debt which has become, without exaggeration, utterly detached from reality. Time and time again, these pundits declaim that hyperinflation is imminent, that interest rates are on the verge of an uncontrollable upward spike, and that the jig will be up for sure just as soon as the next T-bond auction fails. But even though, time after time, it is the pundits prognostications which fail, no one seems to take any notice. This must change. A reality-based economics is needed to make these things make sense again, and Modern Monetary Theory is here to put everyone on notice that a quite different jig is the one thats really up.