The political divide in America is usually articulated in the language of political philosophy, but some important answers to the problems of political philosophy have been answered by science.  We owe a debt of gratitude to Jonathan Haidt for his splendid book The Righteous Mind: Why Good People are Divided by Politics and Religion.

Haidt uses the metaphor of taste buds to explain how the most important human values can be reduced to six flavors or foundations, regardless of history, culture, or socioeconomic status.  Extensive cross-cultural empirical evidence supports his claims.  Our values are like taste buds because they are part of our organism (we have a physical receptor for sweetness), yet our particular circumstances shape how we experience them.  To the dismay of many American tourists, ketchup in Latin America is too sweet.

Here are the six value foundations:

1. Care: This foundation is based on attachment theory and the instinct of mothers to protect their children, but this sentiment can be transferred to strangers as well.  Whereas liberals (supposedly) bestow this on all innocent victims around the world, conservatives bestow this primarily on those who have sacrificed for their group.

2. Fairness: This foundation is based on proportionality and the law of karma, but this sentiment can be transferred to strangers as well.  Whereas liberals equate fairness with rewards and equal outcomes, conservatives equate fairness with proportion, reward, or punishment, even if it guarantees unequal outcomes.

3. Loyalty: This foundation is based on our need to meet the adaptive challenge of forming cohesive coalitions, to include identifying team players and traitors.  Whereas liberals (supposedly) tend toward universalism or globalism, at least in the abstract, conservatives tend toward concrete nationalism.

4. Authority: This foundation is based on the benefits of respecting authority or hierarchical relationships, which includes the burden of responsibility and should not be confused with power.  Whereas liberals often define themselves in opposition to this (unless they are in charge), conservatives tend to embrace it.

5. Sanctity: This foundation is based on a conflict between neophilia (attraction to new things) and neophobia (fear of new things), as it relates to food and sanitation, but extends to people and society.  Whereas liberals sanctify organic food or clean energy, conservatives sanctify religion, guns, and flags.

6. Liberty: This foundation is based on the challenge of avoiding domination in groups and often conflicts with the authority foundation.  Whereas liberals (supposedly) support equality for underdogs, victims, and powerless groups everywhere, conservatives support liberty for their group.

In addition to the evidence-based research on these six value foundations, Haidt's research also reveals how liberals and conservatives view them.  Liberals prioritize care, liberty, and fairness, in that order, but have limited interest in or even disdain for loyalty, authority, and sanctity.  The most sacred value for liberals is care for victims of oppression.  On the other hand, conservatives respect and embrace all six foundations because all six are essential for a meaningful life and a functioning society.  The most sacred value for conservatives is preserving the institutions and traditions that sustain a moral community.