Disposing of Douglas’ first point, that organizing territorial government in Nebraska required the repeal of the Missouri Compromise, Lincoln came to the second:
Second, that in various ways, the public had repudiated it, and demanded the repeal; and therefore should not now complain of it.
One would obviously ask who among the public did such a thing, and Lincoln did. Who beat down Stephen Douglas’ door? Who had the mass meetings and published pro-repeal resolutions? Douglas men did, but they did so after the law went through. One could not sensibly claim that they demanded a repeal they already had and the lack of any agitation on the public’s part for it beforehand puts the lie to the most direct claim. But, Lincoln acknowledged, Douglas did not claim that such a public movement existed per se.
Douglas might have instead pointed to the western Missouri planters who rebelled on David Rice Atchison after he briefly consented to organizing Nebraska with the Missouri Compromise in place, but that would undermine his insistence that he had a national consensus of some kind on his side rather than his actual proslavery capitulation. Instead:
It is not contended, I believe, that any such command has ever been given in express terms. It is only said that it was done in principle. The support of the Wilmot Proviso, is the first fact mentioned, to prove that the Missouri restriction was repudiated in principle, and the second is, the refusal to extend the Missouri line over the country acquired from Mexico.
If the antislavery men, like Lincoln, did not accept drawing the Missouri line out to the Pacific, then they had repudiated its principle. But that does depend on who one asks:
The one was to exclude the chances of slavery from the whole new acquisition by the lump; and the other was to reject a division of it, by which one half was to be given up to those chances. Now whether this was a repudiation of the Missouri line, in principle, depends upon whether the Missouri law contained any principle requiring the line to be extended over the country acquired from Mexico. I contend it did not. I insist that it contained no general principle, but that it was, in every sense, specific. That its terms limit it to the country purchased from France, is undenied and undeniable. It could have no principle beyond the intention of those who made it. They did not intend to extend the line to country which they did not own. If they intended to extend it, in the event of acquiring additional territory, why did they not say so? It was just as easy to say, that “in all the country west of the Mississippi, which we now own, or may hereafter acquire there shall never be slavery,” as to say, what they did say; and they would have said it if they had meant it. An intention to extend the law is not only not mentioned in the law, but is not mentioned in any contemporaneous history. Both the law itself, and the history of the times are a blank as to any principle of extension; and by neither the known rules for construing statutes and contracts, nor by common sense, can any such principle be inferred.
The Missouri Compromise, that solemn pact, did not draw the line to the Pacific even in principle. It covered all the United States that then existed, but not an inch further. Douglas himself had to know as much. So did the political establishment in the late 1840s. Douglas introduced a bill, which a great many endorsed, to extend the Missouri line. In doing so, they all admitted that it did not on its own reach to the Pacific. Thus the fate of slavery in the Mexican Cession represented an open question to everybody, not one on which an instant national consensus existed and then got overthrown by David Wilmot and friends.
We naturally want to side with Lincoln here, but he does have facts in his favor to go with our distaste for slavery. The law itself not include provision for its automatic extension. Nor, for that matter, had previous slavery settlements necessarily transferred to newly acquired lands elsewhere in the nation’s history. The Northwest Ordinance banned slavery. The later Southwest Ordinance did not. The Missouri Compromise permitted some slavery and forbade other slavery. All of that might add up to a kind of geographic partition, but only inadvertently. The United States did its slavery policy on an ad hoc basis as new land came under its control. The Mexican Cession just represented the latest parcel to come up for an ad hoc settlement.