The answer to this question can be found in Stephens's famous "Cornerstone Speech," delivered in Savannah, Georgia in March of 1861. Essentially, the speech is an explanation and a defense of the Confederate Constitution. After outlining some of the main differences between the Confederate constitution and that of the United States, he claimed that its best feature was that it eliminated the possibility for further "agitation" about the issue of slavery, which of course, had led to the creation of the Confederacy in the first place. Stephens said that many of the Framers of the United States Constitution and other Founding Fathers had, even while allowing for slavery's existence (he was talking in particular about Thomas Jefferson) still believed that blacks and whites were fundamentally equal, the Confederate Constitution was based on the opposite principle:
Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner- stone rests, upon the great truth that the negro is not equal to the white man; that slavery subordination to the superior race is his natural and normal condition.
Only "a defect of reasoning" could possibly persuade someone that the races were equal, Stephens said. He went on to offer an expanded theory of racial inequality, claiming that this was the rational basis for slavery, and because the Southern states understood this truth, they would be successful in the long run.