At its core, there are two parts to Modern Monetary Theory (MMT). The first is a description of how the monetary system actually works, mostly focusing upon interactions between the central bank, the treasury, and the financial system, though this part also requires a very thorough understanding...

Legal restrictions theory suggests that interest-bearing money would dominate if there were no legal impediments precluding competition with non-interest-bearing currency. There are very few historical examples with meaningful issues of interest-bearing currency, however, and these tend to occur...