The never-ending controversy over the cause of the civil war is fueled, I believe, by a parochial regionalism, a subconscious one to some of us. The mere geography of our individual lives produces a knee-jerk reaction among even those of us with the most rudimentary understanding of nineteenth century politics.
One reason the arguments usually end in stalemate, I believe, is that we too often confuse a political fact with the social milieu in which it existed, and we wind up trying to conflate the two, and in the process, spoiling the argument. We think we're arguing oranges, when in fact we're arguing apples and oranges.
There is a difference between the "cause" of the civil war and the reasons for which it was fought. Let me try to makes some sense of what on the surface may sound like an introduction to Orwellian doublethink.
The antiseptic "states' rights" was the proverbial whited sepulcher designed to mask the rotten core that the proponents of slavery could not defend in its own right. So repulsive to human instinct is slavery that its defenders were reduced to quoting scripture to interject the almighty into their side of the argument.
Those who argue today that "states' rights" was the pivot on which the war turned do so for a variety of reasons. Some actually believe it. Others adopt it as a convenient way to deflect the pain of defeat off oneself and onto one's political and philosophical opponents.
You could say the rights of southern states would have been served by expansion of slavery to states newly emerging from the territories. The purported goal of success in that endeavor would have been a national government sympathetic to and supportive of the idea, but one which left to the individual states the right to choose for themselves whether or not to permit it. Such a benevolent attitude (toward rights, not slaves) might have been a noble one in the minds of slavery's proponents, but I doubt it. It's an argument made from a position of relative weakness. It would be contrary to human nature to embrace such an idea once the power to impose one's will had been achieved.
The proponents of states' rights have long since abandoned any such pretext. When was the last time you heard Sarah Palin or Rush Limbaugh support the right to choose? At this moment state Republican platforms include the plank of passing a law outlawing homosexual acts, and who seriously believes they would, if given the power to do otherwise, leave it to states to give women the right to exercise control over their own bodies? Likewise, I believe the goal in 1860 was to morph the states' rights argument into national prerogative, once the war was won.
The driving force behind the states' rights effort was, of course, slavery. You don't seriously think the southern states fought the war in order to install the Mint Julep as the state cocktail of newly emerging states - although the julep does play symbolically into one of the reasons for fighting the war, i.e., the perceived desire to preserve a way of life. Now whether or not you believe this was the cause of the war - I hope you don't - it was undoubtedly a psychological reason for fighting it for southerners in whose minds northerners had been demonized, even from the pulpit - maybe especially from. They did not want to see the south slowly converted to another version of the rapidly industrializing north, with its inherent urban issues.
We tend to forget today what overriding pride there was in statehood over a suspect national sovereign, even in the north. Remember, it was only 80 years before that sovereignty had been wrested from an English monarchy. Once the war began, there was the natural reaction of southerners to invasion by what they considered a foreign country. In such a situation people without a cause to champion will quickly embrace a reason to fight.
And of course, Lincoln's own personal ambivalence toward the cause of the war did not deter him from his reason for fighting it. Lincoln's reason for fighting it was not the cause of the war. His reason was preservation of the union, to the extent that he himself declared that he would have permitted slavery if it would have preserved the union. In fact he did permit slavery when he exempted border states from the emancipation proclamation.
I would be remiss not to mention the draft. The draft riots in New York, punctuated by the lynching of innocent blacks, were ample evidence that slavery was not the reason thousands of union soldiers fought. Racism was ubiquitous and fighting on the side of one economic system over another sometimes reflected one's own involuntary servitude, rather than any serious moral repugnance toward the enslavement of someone else, especially someone widely regarded as subhuman.
And finally, as Big John Teague so eloquently reminds us, "It's all about the money boys, it's all about the money." While slavery was all important to the economic interests of the plantation owners, it was also a threat to the bottom line of northern mill owners, who wanted a monopoly on southern cotton and southern markets for their industrial output. The change in congressional representation within congress if the number of slave states increased was a threat to the political power enjoyed by these industrialists and their ability to control the international trade that inhibited the south's ability to sell their cotton overseas and import foreign manufactured goods. If bananas had threatened their monopoly, then bananas would have been the cause of the civil war as far as northern industrialists were concerned. That money held so much sway in this fight is most disturbingly illustrated by the 150 or so free blacks who owned slaves.
So, my point is, there would be far greater agreement that slavery was the cause of the civil war, and less confusion with individual reasons for fighting it, if the argument were more clearly defined at the outset, and if unwarranted moral high ground was left unscaled.
At least among rational thinkers. Not so much for teabaggers.