From a Keynesian perspective, what is considered the main driving force in an economy?

The correct answer is aggregate demand, which is viewed as the primary driving force in the economy from a Keynesian perspective. Keynesian economics emphasizes the importance of total spending in the economy and its effects on output and inflation. According to this framework, fluctuations in aggregate demand—the total demand for goods and services within an economy—are what lead to economic cycles, including recessions and expansions.

In times of economic downturn, if aggregate demand falls, it can lead to decreased production, increased unemployment, and a slowdown in economic growth. Conversely, when aggregate demand rises, it can drive economic growth and reduce unemployment. Keynesians advocate for government intervention, such as fiscal policies, to help manage aggregate demand and stabilize the economy during these fluctuations.

While supply and demand are fundamental economic concepts, in the Keynesian model, it's the demand side that primarily drives economic activity, particularly in the short run. Moreover, while aggregate supply plays a role in economic modeling, it is not considered the main driving force by Keynesians. Government regulations, while influential, are seen more as mechanisms that can affect the economy rather than the central driving force like aggregate demand.