Can Evolution Explain Why There Are Two Predominant Ideologies Rather Than Just One? Maybe Yes.

Evolution shaped our minds as well as our bodies. 

Our bodies are all the same. We all have the same basic structure, organs, etc., and they all work the same way.

It seems only natural that our minds would all work the same way too.

But that’s not the case. Research into human thought consistently shows it to be dominated by two different ways of perceiving, processing, understanding, and reacting to the world. People experience the world differently depending upon which of the two wiring schemes they’re born with. They have different conceptions of what it is, how it operates, what it can be, and what it should be. They have different conceptions of the nature and purpose of knowledge and reason, and the amount of influence they have over all of it. Based on these differences they respond to the world differently, situate themselves within it differently. They have different conceptions about their role in all of it. They live in different realities. Parallel universes do exist.

How could that be? How could the adaptive pressures that gave all of us essentially the same physical body have given us two such different types of brains?

One possible explanation is offered by Arthur Herman, in his book The Cave and the Light: Plato Versus Aristotle, and the Struggle for the Soul of Western Civilization. Quoting at length from Chapter 21, but even so telling the story in only broad strokes:

The result was the first full-blown theory of human progress. It divided human history into four distinct stages of growth, based on how human beings make their living (what later Marx would call “the means of production”). “Hunting and fishing,” Lord Kames wrote, “were the original occupations of man,” when the notion of human society hardly existed. The second stage of human evolution came when humans learned to follow animal herds and later domesticate them.

This pastoral nomadic stage was the world of Scottish Highlanders as well as the Laplanders of northern Europe and historically the Germanic tribes who had invaded the Roman Empire. The pastoral nomadic society is built around the extended family ties of tribe and clan. “If that may be called a society,” Kames added, perhaps with a uneasy glance toward the Highlands outside his window, “which hath scarce any other than a local connection” and lacks any awareness of a larger world outside itself. 32

Instead, for Kames “the true spirit of society” was one that Aristotle would recognize. It “consists of mutual benefits and making the industry of individuals profitable to themselves as well as others.” This must wait until the third stage, the agrarian stage, when the need to bring in an annual harvest “connects individuals in an intimate society of support.” The community ceases to be mobile and becomes fixed in the village, farm, and field. New crafts arise—plowman, blacksmith, carpenter—and new relationships: lord and tenant, master and slave.

This was the medieval Europe of the Domesday Book and the Crusades—but also the Magna Carta. Civil society in its agrarian stage supplies new forms of cooperation, but also new conflicts. With it comes the first sense of natural right as well, Aquinas’s and Locke’s individual claims and obligations, which in Lord Kames’s words, “earlier custom cannot control.” Resolving them requires for the first time written law and permanent government. The law code, the circuit judge, and the royal palace gradually replace the patriarch of the clan or elders of the tribe. For those who depend on their authority, this is a marked advance. However, they owe this advance not to the benevolent character of their rulers or divine sanction, as rulers themselves try to pretend, but to the changing nature of society itself. “In every society,” Kames concluded, “the advances of government toward perfection are strictly proportioned to the advance of society” toward mutual cooperation and improvement. The better we all get along, in other words, the more benign our rulers can afford to be.

However, the progress of civil society is still not done. There is a fourth, commercial stage to come: the world of the businessman and tradesman. The scene of the action shifts from the village to the town and seaport, from farming and cultivating the land to trade and cultivating the exchange of goods and services. A new kind of community springs up, the polished urban world Voltaire and Shaftesbury praised. It is a community with a new complexity, but also with a new unprecedented dynamism.

Commercial society, wrote Kames’s friend William Robertson, is “a society of human beings bound together by one of the strongest of all ties, the desire of supplying their mutual wants.” Cleric as well as historian, and famed provost of the University of Edinburgh, Robertson is not as well known a name as Adam Smith or even David Hume.

Yet Robertson’s crucial contribution was overlaying Kames’s dynamic four-stage theory onto the history of Europe. The result was something of a surprise, especially to those writers like Voltaire used to celebrating the Renaissance as the “rebirth of letters” and the start of the modern spirit. What Robertson discovered was that the crucial start of Europe’s commercial stage came in the Middle Ages, that despised epoch that Voltaire, Shaftesbury, and many others dismissed as an age of Gothic barbarism. (That term, “Gothic,” would stick for describing its architecture.) The reason was the Middle Ages had also witnessed a brisk revival of trade, especially after the Crusades, which brought a spirit of freedom and independence to its cities that gradually spread across western Europe. “A great body of the people were released from servitude,” Robertson wrote. “Towns became so many little republics, governed by known and equal laws, and liberty was deemed such an essential and characteristic part in the constitution” that any escaped slave living there a year and a day was instantly declared free. 33 In short, what had made the Florence of 1402 free wasn’t Divine Providence or even its laws, but how it made its money through trade and industry—which in turn made men change the laws to accommodate their new sense of freedom.

It was a pathbreaking way of seeing man’s freedom, not as a divine gift but as a product of society itself. Not only did commerce and liberty go together, but they gave history an entirely new, hopeful direction. For Polybius, Saint Augustine, and the other heirs of Plato, human history had been an inevitable downward slide. Now thanks to Kames and Robertson, it turned into a steady upward climb. Robertson conceded some places in Europe had felt the progress of change more quickly than others, as in the Italy of Leonardo and Michelangelo and the Low Countries of Erasmus. Others never did, like the mountainous Balkan regions and the Highlands of Scotland. (p. 376-378)

Social scientist Jonathan Haidt describes something similar in this lecture, in which he discusses how values change within societies as they mature, and uses the following graphic to illustrate the process:

Haidt’s book is divided into three sections. Each section describes one of his three principles of moral psychology:

1) Intuition comes first, strategic reasoning second
2) There’s more to morality than care and fairness
3) Morality binds and blinds

Those three principles do not explain everything that happens in the social world. I suggest that at least one additional principle is necessary:

Missing Principle of Moral Psychology:

Cognitive style comes first, moral matrices follow.

I suggest that brain type precedes, and possibly even determines, Haidt’s moral matrices.