Keynesianism is essentially a denial of the "invisible hand of the market". In the theoretical and empirical research of 1937 decades after the Great Depression, Keynesianism prevailed. It emphasized the government's role in regulating the economy, and its policy proposition was also put forward under the background of economic depression at that time, mainly reflected in fiscal policy and monetary policy. In fiscal policy, it emphasizes increasing government expenditure and investment, stimulating the economy, stimulating the development of related industries, and reducing the number of unemployed people.

It is worth noting that in Keynesian theory, there is a "Keynesian liquidity trap", that is, when the interest rate is lower than a certain level, the central bank's interest rate reduction policy will not stimulate investment. This is because bonds are inversely proportional to interest rates. When the interest rate is lower than a certain level, the bond price can't be higher, and investors expect that the bond price can't go up any more, so they would rather hold money than buy bonds, so banks have no money to lend.

The so-called monetary policy is completely useless, which stems from the theory of currency neutrality put forward by Friedman, the leader of Chicago School. He believes that monetary policy is ineffective for a long time, and the government's frequent regulation of interest rates will only aggravate economic fluctuations. Therefore, monetarists essentially advocate inaction and emphasize that the central bank should not interfere in the market.

So, I don't know if I can solve the problem for the subject, but I can ask.