Monetarism is an economic school that argues for a controlled and stable money supply. Friedman believed that inflation was a monetary phenomenon, and that a expansionary monetary policies that increase money supply very fast always lead to inflation.
Ever since, monetarism has come to dominate most central banks in the world, including the Federal Reserve. Before Friedman's theories, central banks were more likely to be keynesian, in the sense that they would target unemployment instead of inflation.
Carley's opinion is that a puppy would be a great birthday gift. She uses scientific evidence about children learning responsibility to support her opinion.
a secondary source would be if someone were to write a speech about the declaration of independence, the declaration of independence itself is a primary source