In a perceptive blog post on the present dust-up in Ukraine, Walter Russel Mead pointed out that most of the media believed that economics would prevent Putin from invading Ukraine. Whether because of his weak economy or resultant trade problems, the possibility of serious economic damage would prevent him from sending troops across the border.

The sad thing is that we’ve been here before: both in 1914 and in 1939, experts around the world believed for the exact same reasons that Europe would not collapse into warfare. Countries were too economically interconnected, they said. A war would devastate everyone, they said. No-one would really gain from such a war, they said.

Here’s the thing, though: the experts were absolutely right. Both WWI and WWII destroyed European trade and commerce. They ended tens of millions of lives and destroyed their families, turned tens of millions of civilians from working citizens into destitute refugees, thriving factories, farms, bridges and roads into bomb craters and food-exporting regions into scenes of hunger. By any rational economic calculation, the wars made no sense.

But that’s the point — people are not purely rational calculating machines, thinking only about profit and loss. We are people of emotions and other, less tangible values such as love, honor, revenge and many more which cannot be swept away or easily dismissed by an Austrian economist or by Freakonomics. Much as our present liberal or even our libertarian thinkers would like to believe, human behavior – be it on an individual or state level — cannot be reduced to mathematical equations or hypothetical discussions of incentives. We’re far too complex for that.

You would think that the 20th century would teach us this lesson for good. Apparently, we need to be retaught every generation.