I was in my post-grad American Economic History class with my relatively liberal professor this morning. He was discussing slavery as an economic institution and mentioned the Dred Scott Case (1857) in which it was declared by Chief Justice Taney (a Catholic, by the way) that slaves were property of their masters, not citizens, and had no rights under the law. He commented on how horrible it was that so many were able to be kept in bondage, and then pointed out how beneficial it was that the 13th amedment freed the slaves, the 14th granted them citizenship, and the 15th voting rights. All the other liberals in the class were nodding in agreement (and it is a good thing to agree that slavery is bad).
Then, when it was time for questions, I said, "How is that issue any different than the current controversy over abortion, in which a woman's child is declared her property and deprived of life without sue process of law?" The room went silent and he got a dumb look on his face. But his response was interesting, especially since he is kind of a liberal (or so it seems from certain comments he makes).
He said that slavery was entrenched in the Constitution while abortion sprung from a mere decision of the Supreme Court. Therefore, he said, slavery had much more of a constitutional basis than abortion and was much more entrenched in society. Then he went on to another topic. Although he did not answer my question on the moral similarity between abortion and slavery, he did point out something: slavery was enmeshed in the Constitution, and was yet overturned and overthrown, and is now accepted by all peoples as being morally reprehensible. Abortion, as springing only from a decision of the Supreme Court, is on much shakier ground constitutionally than slavery.
Conclusion: If slavery, which was constitutional, could be overthrown, then abortion, which is not in the constitution and is on shakier ground, could (in theory) be much more easily overthrown legally if we just had the people to carry it through.
In closing, look at this excerpt from this article on lame-duck President James Buchanan, the predecessor of Lincoln. Look at how it phrases Buchanan's position on slavery and see if it rings any bells: "Buchanan personally opposed slavery, but as a public official he felt bound to sustain it where sanctioned by law. Political enemies called him a "trimmer," but he took middle ground consistently as a matter of policy. What some considered impotent vacillation was an expression of three fundamental convictions: (1) that only by compromise between the parts could a federal republic survive; (2) that citizens had to obey the law even when they thought it unjust; and (3) that questions of morality could not be settled by political action. Despite the secession movement, he succeeded in preventing hostilities between North and South, and he turned over to Lincoln a nation at peace with eight slave states still in the Union."