Question

What reasoning did Lincoln use to support the Emancipation Proclamation?

Answer 1

Answer:
Lincoln reasoned that slavery was morally repugnant, and he had the support of abolitionists and Republicans to abolish slavery.

Details.
President Lincoln moved cautiously in signing a presidential order which did not pass through congress in order to become law.
Consequently, President Lincoln called for a constitutional amendment which was enacted in 1865, and eliminated slavery.