You do not understand the monetary system. You also do not understand what inflation is. You also do not understand how inflation is caused or how it is controlled. You also do not understand that the monetary system fundamentally changed in 1971 (the US voluntarily defaulted and created a new currency). It is also not true that "we've run that experiment." It is also not true that I think the government "should just print money." It is true that I think the US government can and should spend more money, and that it does need to collect dollars from citizens to accomplish that.
We are not on the gold standard or any other convertibility standard, but your positions are based on the assumption that we are. In this way, you are much closer to Ron Paul than you might think. All of your policy analysis flows from a failure to grasp the implications of the switch in the monetary system that occurred in 1971. If you ever wondered why Libertarians sneer at fiat money, it is because it democraticizes money and places it fully within the control of the public (as opposed to pegged to some commodity over which they have no real collective control). Fiat money creates policy options that do not otherwise exist, including freedom from taxation for the purpose of raising revenue. (Taxation is necessary for other reasons, just not to finance the government's spending.)
For a (very) brief spell in 1945, the US had a fiat monetary system also. This was after the gold standard had broken down but before the Bretton Woods agreement that re-restablished currency convertibility and fixed exchange rates. The Chairman of the Federal Reserve Bank of New York at that time (Beardsley Ruml) gave a speech to the American Bar Association during this period entitled "Taxes for Revenue are Obsolete." And in that speech, he said:
The necessity for a government to tax in order to maintain both its independence and its solvency is true for state and local governments, but it is not true for a national government. ...
Final freedom from the domestic money market exists for every sovereign national state where there exists an institution which functions in the manner of a modern central bank, and whose currency is not convertible into gold or into some other commodity.
The United States is a national state which has a central banking system, the Federal Reserve System, and whose currency, for domestic purposes, is not convertible into any commodity. It follows that our Federal Government has final freedom from the money market in meeting its financial requirements. Accordingly, the inevitable social and economic consequences of any and all taxes have now become the prime consideration in the imposition of taxes. In general, it may be said that since all taxes have consequences of a social and economic character, the government should look to these consequences in formulating its tax policy. All federal taxes must meet the test of public policy and practical effect. The public purpose which is served should never be obscured in a tax program under the mask of raising revenue.
http://www.constitution.org/tax/us-ic/cmt/ruml_obsolete.pdf
Let that sink in a bit in relation to the NPR article and what Simon Johnson was asserting. It may well be the case that spending more in aggregate on social security will result in a need to raise taxes (although I seriously doubt it), but that will not be because the government needs revenue. It will be because it is necessary to reduce aggregate demand and the prospect of inflation. From an MMT perspective, the need to raise taxes to reduce aggregate demand is a good thing, because it means the economy is full steam ahead.
EV, what of this notion to "pay off our debt":
Simply mint some $500B coins and "payoff" the debt. They would effectively be unusable as currency, but would they not satisfy the debt?