I know you’ve all been waiting with ‘bated breath for it…
The Declaration of Independence was written by Thomas Jefferson. Jefferson was very much in the tradition of Continental Rationalism. And that really stands out in the Declaration. And that was totally appropriate for the Declaration.
But the Declaration was much more a work of persuasion and explanation and ideals, while the (future) Constitution was a nuts-and-bolts manual for how the government should work. So a different animal entirely.
As for the Constitution, Jefferson thought the Constitution should be re-written every 20 years or so. You know, a “living” document. Jefferson’s position has been espoused by and blown up by the Left at least since 1900 or so.
He and Thomas Paine were very much that in that Rationalist tradition. But most of the other founders of the nation were absolutely not–they leaned toward Hume–and they modeled the government on a more ideal form of the British government (though, of course, without a King). They were Empiricists, not Rationalists. They wanted what had been shown to work, not some amalgam of airy-fairy suppositions.
So the Articles of Confederation were too loose, and we needed to turn to Federalism rather than to the previous CONfederacry (just why that is and why it was necessary in order to get all 13 colonies to get on board is a discussion for another day).
So in 1887, the Constitution was adopted. But Jefferson was gone–he was the ambassador (in France?) by then. So it was written by the empiricists who were there. Had Jefferson been involved, it would have looked very different!
So let’s take a moment and be thankful that Jefferson was there to write the sublime Declaration but was gone and therefore couldn’t muck up the Constitution.