[HPsquared]

It's not the only cause. Money is (pretty much) created whenever anyone borrows.

It just so happens that the government is a very, very large borrower. But people taking out mortgages, student loans, car loans also increase the money supply.

It's like matter and antimatter. When a loan is made, a combination of debt and money is created. When the loan is repaid, the debt and money delete each other. (With fees, interest, and defaults causing a transfer one way or the other). I think bankruptcy deletes the debt but keeps the money, too (not sure about that).

More debt in the system == More money in the system.