What are the Roles of Government?

Americans hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed.
To this end, Americans have empowered the government of THE UNITED STATES OF AMERICA to lay and collect taxes, duties, imposts and excises, but only to pay the debts and provide for the common defense and general welfare of each of the United States; To borrow money on the credit of the United States; To regulate commerce with foreign nations, and among the several states, and with the Indian tribes; To establish a uniform rule of naturalization, and uniform laws on the subject of bankruptcies throughout the United States; To coin money, regulate the value thereof, and of foreign coin, and fix the standard of weights and measures; To provide for the punishment of counterfeiting the securities and current coin of the United States; To establish post offices and post roads; To secure for limited times to authors and inventors the exclusive right to their respective writings and discoveries; To constitute tribunals; To define and punish piracies and felonies committed on the high seas, and offenses against the law of nations; To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water; To raise and support armies for no longer term than two years; To provide and maintain a navy; To make rules for the government and regulation of the land and naval forces; To provide for calling forth the militia to execute the laws of the union, suppress insurrections and repel invasions; To provide for organizing, arming, and disciplining, the militia, and for governing such part of them as may be employed in the service of the United States; To exercise exclusive legislation in all cases whatsoever, over such District (not exceeding ten miles square) as may, by cession of particular states, and the acceptance of Congress, become the seat of the government of the United States, and to exercise like authority over all places purchased by the consent of the legislature of the state in which the same shall be, for the erection of forts, magazines, arsenals, dockyards, and other needful buildings; to make treaties; to adjudicate all cases, in law and equity, arising under this Constitution, the laws of the United States, and treaties made, or which shall be made, under their authority;--to all cases affecting ambassadors, other public ministers and consuls;--to all cases of admiralty and maritime jurisdiction;--to controversies to which the United States shall be a party;--to controversies between two or more states;--between a state and citizens of another state;--between citizens of different states;--between citizens of the same state claiming lands under grants of different states, and between a state, or the citizens thereof, and foreign states, citizens or subjects; to declare the punishment of treason; to prescribe the manner in which public acts, records, and proceedings shall be proved, and the effect thereof; to admit new states; to dispose of and make all needful rules and regulations respecting the territory or other property belonging to the United States; to guarantee to every state in this union a republican form of government, and protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened) against domestic violence; to propose amendments to the Constitution and nothing else.