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fundamental principle established by the Declaration as “consent of the governed.”
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exactly, and as slavery deprived the slaves of their ability to give consent, it was a completely invalid institution.
"Consent of the Governed" only applies to citizens. Slaves were not citizens.
Look, I know we would all prefer that everyone at the time accepted Christian principles of equality, but they didn't. Pretending they did is wrongheaded and foolish.
The people of those times were quite racist and quite willing to practice subjugation of other people. It is what it is, and not what we would have it be.
It is also a mistake to believe the Northern powers launched a war to stop slavery. They didn't. In fact, they were falling over backwards to offer the South more protection for slavery if the South would simply remain in the Union.
It didn't work, and now people are embarrassed at the lengths to accommodate slavery which the Northern representatives enacted. Nobody is taught about the "Corwin Amendment" precisely because it undermines their claim as to why the war was fought.