Over the years some people have noticed humans have an unfortunate and largely anachronistic tendency to form tribal groups and to designate other tribal groups as The Enemy. Whether these groups identify on grounds of nationality, religion, ethnicity or something else entirely is immaterial. The danger lies in the psychological mechanism itself.
The problem being it inevitably leads to death, destruction and suffering, sometimes on a small scale, like the recent mob violence directed against Zimbabweans in South Africa, or on a large scale, such as the wars in the Balkans in the 1990s, or on an unprecedented and world changing scale, as happened under Hitler.
A lot of energy has gone into short-circuiting this mechanism since the end of the second world war. Because it seems to be innate, constant vigilance is required to prevent it from being triggered. Now you may think this is all in vain, and that Man shouldn’t set himself against Nature, but I disagree. Whatever the shortcomings of Liberal Humanism, I think that in this regard it is Noble and Necessary.
When ‘leftists’ squawk and flap and denounce Trump, for example, as Hitler, or as a Fascist, this may seem hysterical but ultimately it is a response to seeing someone reaching for the big red Tribal Passions button. We know what happens when that button gets pressed. It’s not pretty.
There’s lots of issues around this subject to talk about and squabble over, and I'd enjoy doing that, but there’s also something non-negotiable at its heart.