For when you assemble a number of men to have the advantage of their joint wisdom, you inevitably assemble with those men, all their prejudices, their passions, their errors of opinion, their local interests, and their selfish views. From such an assembly can a perfect production be expected?..."perfect production" -- ?
That's my problem with Franklin. He was too much the theorist or rationalist.
What he characterizes as "prejudices", "passions", "opinion" and "local interest" was their disparagment of theory and reliance on history and practical common sense. (See Forrest MacDonald) Both Franklin, who was there but elderly and sleeping some of the time, and Jefferson who was abroad, looked down on the Constitution for the same reason they favored the abstract rationalism, a priori reasoning and metaphysics that led to the French Revolution and all the Terror: They were men of the mind and not the world.
No, my friend, Franklin was an admirable animator, but a poor craftsman.
It is easy for complainers to say the Anti-Federalists were "right", because they never got the second convention they wanted, and so there is no way of knowing what might have come out of a second convention. Why should anyone think the result would have been better? Everyone was represented. They debated. They deliberated. Then they submitted it to the public. What the heck else could any of them have done?
In that practical sense, it seems to me, Franklin was right to say this was the best they were going to do, regardless of whatever criticisms he might have had with it, or upon what basis those criticisms were formed. But hey, what do I know?