Final answer:
To address a recession, a Keynesian economist would use expansionary fiscal policy, involving tax cuts or increased government spending. For controlling inflation, contractionary fiscal policy with tax increases or spending cuts would be employed.
Step-by-step explanation:
A Keynesian economist would address a recession by implementing expansionary fiscal policy. This would entail either cutting taxes to boost consumption and investment or increasing government spending to shift the aggregate demand curve to the right, encouraging economic growth and reducing unemployment. Conversely, to combat inflation, a Keynesian approach would involve contractionary fiscal policy, which includes raising taxes or reducing government spending to shift aggregate demand to the left, thereby cooling the economy and controlling price levels.