Why do governments borrow money instead of printing it?
If the government prints money recklessly and causes inflation, people will come to expect inflation, and the value of the currency will plummet, and you'll end up like Zimbabwe where a trillion dollars won't buy a loaf of bread.  If the government actually pays people for the money they borrow, they don't have this problem - and as it turns out, the US government can get pretty good rates on borrowing in general, in part because they're extraordinarily good about paying them back. (Also, inflation expectations are low, so people will accept 1-2% interest rates. If you expected inflation of 10%, you'd see people demanding something more like 12% interest rates.) (The downside of too much of this sort of borrowing is that it "crowds out" other borrowing, which may harm the economy. Who would lend money to / invest in a small business, if the government is paying good money and there's almost no risk at all?) Now, inflation can come into play afterward, if the Fed decides it needs to maintain "easy money" policies to stimulate the economy (because taxes are too high because we're paying off the debt, or because we've crowded out smaller borrowers, or something). -- In general, you can count on the the principle that if you, as the government, try to play too many games with people's money... well, people aren't stupid; they will eventually catch on, and adjust their behavior to compensate, and then you're right back where you started, but with less trust.