Can we talk about the Civil War rationally?

I think not secession but ethnostates within the union was, and remains, the natural way to go. Lincoln and Davis were both right and both wrong. We need the union to protect ourselves should other outside powers attack us, but the union needs to relate to real human nature.

Ethnostates or an ethnopluralism of ethnostates relates best to real human nature, which remains as it has always been throughout human history: kin-centered, gender defined, age-graded, heterosexual, marriage-making, hierarchical, ethnocentric, even xenophobic, and religious-making, among other things, with group-selection (or ethnic selection) as the primary unit of successful selection, followed by individual selection.

An ethnopluralism of ethnostates or regions could even be established legally in the United States with our constitutional separation of powers and states, protected by federalism. It may require a few constitutional amendments to give more power to the states.

As to the slavery of the South it was wrong on many levels, but it was naturally falling away with new technically advanced machines for the cotton plantations. In any case, force is not the best long-term way to integrate different ethnic groups, who do not really assimilate, as we see in our prison communities. The military now brags about its integration of races but virtually uses force to do it, rejecting or destroying anyone who doesn't go along with it.

The Ancient Greeks had a better, more natural, way of forming a federation of state militias when the Greek federation was threatened by outside forces. Sure there was competition between the states, and some states were better fighters than others, but what's wrong with that? The competition improved all groups.