"We the people of the United States, in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity, do ordain and establish this Constitution for the United States of America." --Preamble to the United States Constitution
The founding fathers of this country faced a crisis in the 1780's. The economic problems of taxation and debt could not be cured by the current system of government under the Articles of Confederation. The reason the Articles were inadequate stemmed from a lack of federal leadership and the legislative inefficiencies therein. Further inflaming the fears of politicians was a rebellion of farmers in Massachusetts, called the Shay's Rebellion. For these reasons, the forefathers headed to Philadelphia for the purpose of revising the law that would govern the land.
The true purpose that guided the framers of the Constitution is found in the Preamble and all point to significant problems with the Articles. It is useful to analyze the various components of the Preamble to understand the purpose of the Constitutional Convention.
.....in order to form a more perfect union
The old system of government was a confederation by design. That meant that each state was more powerful than the national government. This created the opposite of unity or union. For that reason, citizens did not identify themselves as Americans as much as they would as Virginians, as an example.
.....provide for the common defense, promote the general welfare..
The Articles of Confederation hampered a national standing army for defense and security. Because Congress lacked the ability to levy taxes, it was difficult for the federal government to support a defense system. The lack of clout at the federal level in terms of regulating commerce also made it difficult to promote strong economic development and, therefore, a sense of general welfare among the citizens.
...secure the blessings of liberty to ourselves and our posterity...
Despite the revisions made in the U.S. Constitution that gave the federal government more power and authority, the Framers were still concerned about liberty and freedom. They hoped to strike a balance between the weaknesses of the federal government under the Articles and the tyranny of the monarch government system that they had just broken ties with. The result of the Constitution, at its completion, was a system of government with three branches to separate responsibilities and powers that were reserved to the states.