In modern economies, there's a central authority that decides the currency's inflation. If there's much unemployment (and specifically
cyclical unemployment), the government can lower the interest rates to strengthen private businesses financially. The opposite happens respectively. These tasks are done to make the symptoms of cyclic fluctuations less painful.
Government have agencies whose roles are tied to bringing solution to inflation in the economy system but they lack the implementation policy, such a way that we only know those offices saddled with the responsibility to exist without any significant impact felt on the economy.
The deflationary spiral argument goes as following: Let's imagine an economy that only uses Bitcoin, solely, as currency. When the productivity rises, the price of goods and services decrease.
This is perfectly how an economy should be run. because going by this no one will feels hoarding any currency is the next available option, we tend to hoard because of fear of the future outcome. nothing can bring down productivity as long as law of return on labour is effective.