Final answer:
The core principle in American government with historic roots outside the US is the separation of powers. Government and politics are seen as necessities because they provide structure, protection, and representation.
Step-by-step explanation:
A core principle in American government that has historic roots outside the United States is the principle of separation of powers. This principle can be traced back to the ideas of French philosopher Montesquieu, who argued for the division of power among different branches of government to prevent tyranny. The American Constitution reflects this principle with its three separate branches: the executive, legislative, and judicial branches.
Government and politics are often seen as necessities because they provide the structure and organization needed for a society to function. Without government, there would be no system in place to protect individual rights, enforce laws, maintain order, and provide public goods and services. Politics, on the other hand, is the process by which decisions are made and policies are determined, and it allows for the representation and participation of citizens in the governing process.