I am sure Hummel's book puts some good arguments.
You have to realize, that there are hundreds if not thousands books, documents, and papers defending the conventional view that the civil was inevitable. You can't simply ignore those because you don't like them.
The idea that slavery was on its way out anyway is a popular one, and there is some academic backing to this idea. But, most historians agree that there were too many barriers in place for enough time to have passed for the South to have given up slavery peacefully. Especially since, we know that in real life, the sudden loss of the practically free workforce, as well as the loss of profitability of the slave trade, was an economic blow that the South took years and years to recover from, on top of the damages from the Civil War.
For example, the abolitionists in the North were going stronger and would have pushed for a violent end to slavery. Slaves themselves would have engaged in a violent response that would have required federal intervention either way (either the South demanding federal intervention to help quell the slave rebellion, and the Federal government angering them by not helping or angering the abolitionists BY helping).
The fugitive slave law was also incredibly unpopular in the North. How long would they have tolerated being forced to send slaves back? What if slaves escaped to Canada? Then what would have happened?
Also, it should be noted that following the civil war, government shrank tremendously. In fact, between 1900 to 1910, government spent less as a % of GDP, and taxed less as a % of GDP, than it did during the founding era. World War I created a HUDGE spike in government interference, followed by economic recovery plans and World War II; the government hasn't stopped growing since. But to say that the growth of government in the 1910's was due to a war half a century ago is dubious.
Plan for eliminating the national debt in 10-20 years:
Specific cuts; defense spending: http://rolexian.wordpress.com/2011/01/03/more-detailed-look-a