Woah -- didn't see this

Barack Obama:

I think it’s a remarkable document…

The original Constitution as well as the Civil War Amendments…but I think it is an imperfect document, and I think it is a document that reflects some deep flaws in American culture, the Colonial culture nascent at that time.

African-Americans were not — first of all they weren’t African-Americans — the Africans at the time were not considered as part of the polity that was of concern to the Framers. I think that as Richard said it was a ‘nagging problem’ in the same way that these days we might think of environmental issues, or some other problem where you have to balance cost-benefits, as opposed to seeing it as a moral problem involving persons of moral worth.

And in that sense, I think we can say that the Constitution reflected an enormous blind spot in this culture that carries on until this day, and that the Framers had that same blind spot. I don’t think the two views are contradictory, to say that it was a remarkable political document that paved the way for where we are now, and to say that it also reflected the fundamental flaw of this country that continues to this day.

I assume he's talking about slavery and racism. The Constitution does not even mention slavery or race. The blind spot was in the culture. The document itself was not sullied by slavery, and the Constitution was used to justify the correction of that flaw (which was far from unique in the world at that time.) No change to the document was necessary, though an amendment was made to clarify that race doesn't determine personhood -- men who were created equal and endowed by their creator, etc, etc.

To add to the Constitution the idea that people should be treated differently according to their ethnic backgrounds would be to introduce the non-existent flaw he wants to "correct" in the first place and could be used to justify all kinds of injustices.