If we keep the cart and the horse in their proper places, this is not so difficult.Tariffs as a cause of war makes some sense. But the Midwest states had been adamant about free trade on the Mississippi since the admission of Louisiana. Further Davis administered a toxic rebuke to the shipping companies in New York and Boston when he began to issue Letters of Marque. These things all combined to force a blockade and for foreign countries to limit the rights of the Confederate raiders. Hard to crew a Confederate raider if the crew cannot sell the captures except by taking them into a blockaded port.
The Morrill Tariff was signed into law right before Lincoln took office. It significantly raised tariff rates and could not have passed Congress but for the absent Southern opposition; the Confederacy was being formed at the same time. This was not a cause of secession.
Shortly after this the now formed Confederacy declared for free trade on the Mississippi, and retained a revenue tariff similar to the one in place in the US at the time of secession.
There is at this point no war.
The 1860 Republican Platform declared for Protectionism. US manufactured goods will now have to complete in the Confederacy on an even basis with overseas products. The point of protectionism was that US goods were not competitive. If the Confederacy stands, US manufacturers lose market share, and US wholesalers import fewer goods, decreasing Federal revenue. I can think of no more compelling reasons for Lincoln to take aggressive action against secession. Blockades, commerce raiding, smuggling, all this comes after war starts.
Most public figures were cloaking their intentions with mysticism, invocations of morality and so forth, but, this was about economics.
Lincoln chose war, but in a way that began a conflict he might well have lost.