Nelson Lund explains why in this new article, from the Florida Law Review. Lund is responding an article by Akhil Amar, which does not appear to be available on the public Internet.
Readers who want even more on the subject may enjoy Lund’s 2002 article in the Winter 2002 issue of Constitutional Commentary, responding to a 2001 Harvard Law Review article from Larry Tribe. Tribe wrote a counter-article in Constitutional Commentary; Lund’s reply to that is here. Tribe penned a further response.