To quickly add a further point -- I do find it irksome to hear it said that "a dollar isn't worth anything except what we think it is."
The belief is widely circulated that fiat currencies have no intrinsic value, that they are faith and faith alone. I don't think this is accurate.
To the extent that a government has access to a nation's productive output -- the ability to tax it and harness it WITHIN REASON -- the currency issued by that government represents a claim on the same pool of assets.
By this analogy we can think of fiat currency like shares of stock. $US dollars are shares in America Inc.... Japanese yen are shares in Japan inc., and so on.
The "currency as a share of stock" analogy captures the notion that a nation's currency is a representation of that country's economic output and productive strength, just as a share of Microsoft stock is the same for Microsoft.
But then think about something else. What would happen if Microsoft decided to issue 100 billion extra shares overnight? Or what would happen if Microsoft made a series of internal decisions that wound up killing the business franchise?
Even though a currency unit is like a representational share of a nation's output (to the degree the government has the power to tax), currency units can also be debased and degraded in the same way that over-issuance of shares can dilute value. And the other key point is that IT ALL GOES BACK TO THE REAL VALUE OF THE UNDERLYING ASSETS. (That was actually
the main point of this piece, not the chartalist stuff.)
That for me is what's so frustrating about MMT. They pretend governments have some magic ability that comes from the ether, some free pass that allows them to bypass rational application of the laws of supply and demand. They do not. To the extent a government is economically powerful, it is like the board of a corporation with the ability to issue shares of stock in that corporation.
But the government cannot do whatever it wants and assume the value will always be there. The idea that the U.S. could simply issue capital and price controls in a pinch, for example, overlooks the fact that such a decision might actually completely trash the value of the underlying assets. If Microsoft's board starts thinking "we are invincible and can do what we want," they will be inclined to start making bad decisions that destroy the perceived value of the underlying assets on the whole.
There is no magic, no free lunch, and no mystery as to where value comes from. A unit of currency has value to the degree that it is a representational share of the economic output of the host country. But also like company shares, over-issuance can dilute this value and the board (i.e. the government) can make bad decisions that destroy the underlying value of the franchise.
This is all very basic, straightforward stuff and we don't need a theory like MMT -- which imputes a sort of magical immunity to governments that does not exist -- in order to explain it all.