To provide for the common defense, as opposed to merely a state-based defense, the Constitution contains what came to be known as the Compact Clause: "No state shall, without the consent of Congress, lay any duty of tonnage, keep troops, or ships of war in time of peace, enter into any agreement or compact with another state, or with a foreign power, or engage in war, unless actually invaded, or in such imminent danger as will not admit of delay" (Article I: 10:3) This established a fundamental difference between the defensive capabilities of state governments and the federal governments. Although state governments may have national guards today, all military activities are fundamentally under the direction of the federal government, and no state can enter into a treaty with a foreign power. According to the Commander in Chief Clause: "The President shall be commander in chief of the Army and Navy of the United States, and of the militia of the several states." (Article II: 2:1). The new nation's federal Army and Navy (and later the Air Force and Marines) were placed under the supreme power of the central executive figure (and Congress was given the power to declare war). The reasons that the Founding Fathers inserted the words "common defense" in the preamble was because many of the states viewed themselves as possessing the rights of small nations, and the Founders knew that a nation in which different states had competing treaties with foreign powers would be impossible to govern. Also, if states had powerful self-governing militias, civil war would be virtually inevitable, given the many regional tensions that were already manifest at the time.

To promote the general welfare the Constitution specifically tries to sow the necessary conditions so that new ideas can be promoted. This exemplifies how the Founding Fathers were truly 'men of the Enlightenment,' and interested in promoting positive intellectual developments, according to Article I (8:8): "The Congress shall have power . . . To promote the progress of science and useful arts,...

Supreme Court. Congress also has the power "To regulate commerce with foreign nations, and among the several states, and with the Indian tribes;" and the regulation of interstate commerce has been used to 'bust' monopolistic organizations and illegal racketeering, when they threaten free enterprise (Article I: 8:3)
To secure the blessings of liberty was essential, given that the Declaration of Independence had made liberty one of the cornerstones of the new nation's values. Many Americans were concerned about the creation of a new constitution with a stronger federal authority, because they feared the loss of their liberty. Knowing this, the Founding Fathers included what became known as the Bill of Rights, or the first ten amendments of the Constitution, which defined what individual values could not be impinged upon by the federal government (later, it was decided that citizens were also protected from state governments that attempted to infringe these fundamental values). Also, "the citizens of each state shall be entitled to all privileges and immunities of citizens in the several states," indicating that all citizens were entitled to equal liberties, regardless of the state in which they resided -- an issue which has occasionally given rise to debate, not only in the context of the Bill of Rights, but when states have attempted to regulate certain fundamental liberties such as asking for proof of residency when voting (Article IV, 2, 1).

Works Cited

Garner, Devotion. "Popular names of Constitutional Provisions." University of Washington

Gallagher Law Library. [September 1, 2011]

http://lib.law.washington.edu/ref/consticlauses.html