What function, if any, should government have in the economy?

Is this your assignment?

Depends really. In a powerful enough nation, the government always reaches a point where it becomes an economically considerable factor. Factors such as the fairness of government contracts and geographical distribution become an issue, as well as the effects of government regulatory action and goals of foreign policy and intervention. What I'm saying is that government interaction with the economy is inevitable. It's merely a question of how it should be managed.