The delegates at the Constitutional Convention met to address the weaknesses of the Articles of Confederation.
The Articles of Confederation was America's first constitution developed after America had formally declared its independence from Great Britain. The structure of the Articles of Confederation made it so that there was a very small and weak central (aka federal) government. This small central government was a result of America's experience under Great Britain, as a strong and tyrannical government was a huge cause of why the Americans left Britain to begin with.
Even though this constitution had the best of intentions, it gave state governments way too much political power. Along with this, the federal government had no power to enforce laws or collect taxes.
This is why the delegates met at the Constitutional Convention. Ultimately, the delegates decide that the Articles of Confederation cannot be fixed so they throw it away and develop the US Constitution we use today.
