Answer:
In their attempt to balance order with liberty, the Founders identified several reasons for creating a federalist government:
to avoid tyranny
to allow more participation in politics
to use the states as "laboratories" for new ideas and programs.
As James Madison pointed out in The Federalist, No. 10, If "factious leaders kindle a flame within their particular states," national leaders can check the spread of the "conflagration through the other states." So federalism prevents a person that takes control of a state from easily taking control of the federal governments as well.
Electing both state and national OFFICIALS also increases the input of citizens into their government. And if a state adopts a disastrous new policy, at least it would not be a catastrophe for everyone. On the other hand, if a state's new programs work well, other states can adopt their ideas and adjust them to their own needs.
The Constitution gives three types of power to the national government:
1. DELEGATED (sometimes called enumerated or expressed) powers are specifically granted to the federal government in Article I, Section 8 of the Constitution. This includes the power to coin money, to regulate commerce, to declare war, to raise and maintain armed forces, and to establish a Post Office. In all, the Constitution delegates 27 powers specifically to the federal government.
2. IMPLIED POWERS are not specifically stated in the Constitution, but may be inferred from the elastic (or "necessary and proper") clause (Article I, Section 8). This provision gives Congress the right "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and other powers vested in the government of the United States." Since these powers are not explicit, the courts are often left to decide what constitutes an implied power.
3. INHERENT POWERS are not specifically listed in the Constitution, but they grow out of the very existence of the national government. For example, the United States has the power to acquire territory by exploration and/or occupancy, primarily because most governments in general claim that right.
