I reject the one argument I've heard against it, that the word "posterity" is intended as an amorphous literary convention, and not as a specific attempt to address progeny.
It seems to me that argument would only hold weight IF the authors of the Constitution believed the Republic would quickly fail. If they did not, and truly hoped not, then they would have specifically desired to secure blessings that had substance for the very real posterity who would succeed them and their generation.
Which is even more absurd than the suggestion that the Preamble isn't really "part" of the Constitution (then again, I'm sure it makes total sense to those who think that a baby isn't really "alive" until it can eat and breathe on it's own).
It seems to me that argument would only hold weight IF the authors of the Constitution believed the Republic would quickly fail. If they did not, and truly hoped not, then they would have specifically desired to secure blessings that had substance for the very real posterity who would succeed them and their generation.
And this is even more impossible.
The Preamble speaks of a "more perfect Union" and this is a direct reference to the "perpetual Union" referenced in the Articles of Confederation, the Fathers wanted a more perfect AND perpetual Union(this is also the main argument against the thirteen states that signed the Articles being allowed to secede from the Union), not something that would terminate. The Founding Fathers risked so much personally, it is unthinkable that they wouldn't have envisioned the Republic lasting in perpetuity.