Final answer:
The main purpose for the 1787 convention in Philadelphia was to revise the Articles of Confederation, but it resulted in the drafting of the United States Constitution.
Step-by-step explanation:
The main purpose for the 1787 convention in Philadelphia, known as the Constitutional Convention, was to revise the Articles of Confederation. However, during the convention, the delegates decided to create an entirely new framework for a national government, which resulted in the drafting of the United States Constitution.