Appeals to authority is a well known fallacy of logic. In fact, there are many historical examples of economy's growing without deficits. Further, just because the government borrows and spends the money instead of the private sector spending the money does not make the government spending magically more stimulative than private sector spending. Also, deficit spending is not how money is created. All the borrowing comes from pre-existing money supply. It is not monetized (and by law cannot be). Only borrowing from banks increases the money supply (or faster velocity or turnover of money can have the same effect).
When Truman laid off federal employees after WW2, slashed federal spending, and ran budget SURPLUSES, disciples of Keynes were prophesying the return of the Great Depression, but the economy defied the economists and did just fine.
Well now you've steeped in it. On this matter, I'm as much am Authority as Keynes! Why? Because we can both add and subtract.
They total sum of outside money in the economy is equal to the penny to all the money spent into the economy over the years minus all the money taxed back out. If the money in equals the money out, there will be no excess for savings and investment. That's grammar school arithmetic! the only way to provide an excess over what is taxed back out to accommodate the additional money needed for savings and investment, and for a robust economy, is for the government to tax less than it spends. The difference, to the penny, is the deficit. There must be a deficit if there is to be money for savings and investment. To prevent deflation, at the bare minimum, deficits are needed to accommodate GDP and population growth. All Central bankers understand this basic principle. I don't know who was the first to spell it out so simply for you as I have, but see for example the great Aba Lerner's papers from the 1940's. Or look up Abba Lerner's Laws of Functional Finance. (OOOPS there I go again, relying on authority!)
Now that you've brought up Harry Truman, did you know that in the Truman-Eisenhower era the USA became the manufacturer for much of the world. It was a golden period in US economics. When one country runs a trade surplus it just means at least one other country must be running a trade deficit. It's the same simple arithmetic.
In an open economy, the flow of aggregate savings is equal to investment plus the governments deficit, plus net exports. (net exports are exports minus imports) If Nation X (The U.S. after WWII) runs a trade Surplus against Nation Y , then X will accumulate financial claims against Nation Y. X has a trade surplus, Y has a trade deficit. In other words, if a nation runs a big enough trade surplus, they won't need deficits to accommodate savings and investment.
Today, and even in Truman's time too, if the U.S. ran big surpluses repeatedly, the country would be soon enough thrown into recession and then depression unless of course we can again run big trade surpluses.
This interesting statement of yours caught my eye... :
"just because the government borrows and spends the money instead of the private sector spending the money does not make the government spending magically more stimulative than private sector spending."
The government actually doesn't borrow, it only appears to be borrowing. And the concept of debt for the government is meaningless. But government does have practical constraints it must operate under. It is just that sovereign bonds only give the appearance of the government borrowing, when in fact they serve an entirely different purpose.
N.B. -- credit is the major source affecting the money supply under normal circumstances, which surprisingly, you do seem to comprehend.. I call credit money "inside money". This inside money is created when a loan is made, and disappears when the loan is paid back. The ultimate source of money however is the "outside money the government creates" and spends into the economy.