there is the considertion
does a person have the right to change their mind, ever? or if they change their minds, are they hypocrites?
When would such a thing ever ever ever be justified? (according to your principles)
A person does have the right to change their mind, absolutely. I think people need to be careful with flip-flop claims, although at times it is appropriate.
Are you saying Lincoln changed his mind on his support of the Declaration of Independence?
he demonstratively was dragged kicking and screaming into the abolitionist camp (whom he had previously labelled "radicals")
And his dedication was to the principles he saw enshrined in the declaration, things like "all men are created equal"
I imagine that he would see that as the superior principle
which doesn't answer the question . . . .
"When is is justified to change your mind?"
I disagree with Lincoln's choice for above stated reasons and I see him as hypocritical. If you feel disregarding our country's founding documents was necessary to your purpose, fine, but do not then go forth lauding their virtues.