Why did Alexander Hamilton support ratifying the Constitution?

The question strikes at the very heart of my life's work, and I can answer it directly. My support rested on a clear-eyed diagnosis of what the Articles of Confederation had produced: weakness, disunion, and the prospect of worse to come. In my Conjectures About the New Constitution, I set out plainly what stood in the Constitution's favor: “a strong belief in the people at large of the insufficiency of the present confederation to preserve the existence of the Union and of the necessity of the union to their safety and prosperity”. That belief was widespread — and it was correct. The commercial interest, men of property, and public creditors all had concrete reasons to want a government with real authority. I catalogued them candidly: merchants wanted a government capable of regulating and protecting commerce; creditors held “hopes of the Creditors of the United States that a general government possessing the means of doing it will pay the debt of the Union”. These were not narrow grievances — they were the material foundations of a republic worth the name. At the Convention itself, as recorded in Madison's notes of my speech, I declared that the crisis was “too serious to permit any scruples whatever to prevail over the duty imposed on every man to contribute his efforts for the public safety & happiness”. Was the final document everything I wished? No. But the Constitution was vastly superior to the ruin we already had, and I signed it, argued for it, and wrote the greater part of The Federalist in its defense.