Which founding document outlines the purposes of the government?

The Constitution is the founding document that outlines the purposes of the government. It begins with a preamble that explicitly states the goals the government aims to achieve, such as establishing justice, ensuring domestic tranquility, providing for the common defense, promoting the general welfare, and securing the blessings of liberty. This clear articulation of governmental objectives sets the framework for the organization and operation of the government as it defines the structure of the United States government and the responsibilities of its various components.

In contrast, the Declaration of Independence primarily serves to explain the reasons for the American colonies' decision to separate from British rule, focusing on individual rights and grievances against the monarchy rather than outlining how the government should function. The Federalist Papers are a series of essays promoting the ratification of the Constitution and discussing its principles but do not serve as a foundational document in the same way the Constitution does. Lastly, the Articles of Confederation established a framework for governance prior to the Constitution but were largely ineffective and did not adequately address the purposes and powers of the government as clearly as the Constitution.