The ability to think clearly and make good decisions is on almost every society’s list of virtues. In this essay I discuss the debate over different aspects of intelligence, the degree to which they are shaped by genes, chemistry and society, and the role of intelligence in other virtues.
In this series:
Wisdom and the Intellectual Virtues
In this project I have avoided use of the term “wisdom.” There are psychological instruments that attempt to measure wisdom, but not very coherently. They ask respondents to answer questions about themselves that tap lots of different strengths such as emotional regulation, perspective on life, curiosity, compassion, sense of humor, tolerance of uncertainty and spirituality. In other words, wisdom is often a kind of catchall for all of the virtues that I am discussing in this project. In this essay I want to narrow in on a much more specific form of wisdom: the ability to reason, plan and think abstractly, to understand complex ideas, to learn quickly, and to apply an understanding of oneself, other people and the world to making good decisions.  In other words, intelligence.
Perhaps it is not a surprise that I would arrive at the conclusion that intelligence is a virtue since the two principal transhumanist obsessions are life extension and cognitive enhancement. But intellectual virtues are a part of most virtue ethics schemes. The positive psychologists’ Virtues in Action or "character strengths" scheme includes a number of intellectual virtues: prudence, creativity, curiosity, judgment, love of learning, and perspective. Buddhism focuses on two broad types of intellectual virtue, the abstract capacity for “penetrating insight” (prajna) and the ability to skillfully apply insight and knowledge to make good decisions in life (upaya). Similarly for Artistotle intellectual virtues were divided into abstract abilities like the capacity for reason (nous), theoretical insight (sophia), the ability to deliberate (euboulia) and judgment (gnome), and more practical abilities like empirical knowledge (episteme), prudence (phronesis) and cleverness (deinotes). Virtue itself is form of learning for Aristotle, the ability to learn what is right and then convert doing the right thing from a conscious effort into an unconscious habit.
What is Intelligence?
As with the other virtues, our capacity for intelligence is somewhat fixed at birth but can also be impaired or improved by environment and behavior. Studies of twins and of family heritability suggest that differences in general intelligence are between 60% and 80% genetic, and the degree to which genes predict our intellectual abilities increases as we age and our brains mature. Inherited genetic capacities for intelligence at birth and general intelligence in childhood predicts academic achievement, job performance and income, as well as health and longevity. General intelligence is correlated with brain volume and cortical thickness, features which are also partly genetically determined,   but which can also be boosted by lifelong learning.
Although the genetic influence on intelligence is strong, there are many genes that shape general intelligence, and none have been found that individually have a large effect. The genes for intelligence are finite though; in a recent study of more than 3000 pairs of twins a British team identified genes that accounted for two-thirds of the genetic influences on general intelligence. Genes for general intelligence shape our cognitive capacities in many domains, contributing for instance to both our reading and mathematical abilities, which is why a single intelligence model works as well as a multiple intelligence model.
Psychometricians do find it useful to distinguish between fluid intelligence and crystallized intelligence however. Fluid intelligence is the ability to solve novel problems, and is the more genetically innate ability, tied to the size and efficiency of the prefrontal cortex. Cystallized intelligence is the amount of knowledge we have about the world and about ways of doing things, like mathematical calculation. Differences in crystallized intelligence are also shaped genetically, but less so than fluid intelligence, and the two abilities are shaped by different features of the brain. Environmental enrichment and education can improve crystallized intelligence but less so fluid intelligence. Fluid intelligence peaks around age twenty while crystallized intelligence continues to grow until we begin suffering memory loss in old age.
Other sub-types of intellectual abilities can also be teased out, such as executive functioning, creativity, reading comprehension, mathematical ability, spatial visualization, and social and emotional intelligence. But it turns out that all these abilities are pretty closely tied to overall or “general intelligence,” which is why my Venn diagram of the virtues has intelligence overlapping with self-control, caring and positivity.
- Flourishing, which is the use of intelligence to cultivate a meaningful and fulfilling life (Enhancing Virtues: Positivity)
- Mindfulness or executive function, which is a component of both self-control and intelligence (Enhancing Virtues: Self-Control and Mindfulness)
- Social intelligence, intelligence about one’s own and other people’s minds, which is necessary for cognitive empathy (Enhancing Virtues: Caring)
- Fairness, which is the application of intelligence to moral reasoning and to habits of mind that reduce cognitive biases (Enhancing Virtues: Fairness)
- Transcendence, which is the experience of creativity and unusual states of consciousness that bring insight and perspective, “spiritual intelligence,” into daily life (Enhancing Virtues: Transcendence)
Openness to Experience In personality research the “openness to experience” trait is the strongest correlate of intelligence.  Like the other OCEAN personality traits our genetic settings at birth account for about half of the variation in openness. A study of 9400 partcipants from Canada, Germany, Japan and Italy found that the heritability of openness was better than 50%. Our genetic settings for openness also appear to be closely related to our settings for general intellgience. A study of 650 sets of twins’ found that shared genes accounted for almost all of the correlation between the twins’ openness to experience and their intelligence, suggesting that they are in fact two aspects of the same thing at the genetic and neurological level. Some personality theorists have even relabeled the personality trait as Openness/Intellect.
Curiosity and Need for Cognition Both intelligence and openness to experience are related to a tolerance for, and even enthusiasm for, ambiguity, novelty and complexity. People differ in their capacity for complex thought, but they also differ in their enjoyment of complex thought. In psychology the degree to which we are drawn to challenging thoughts and tasks is known as “need for cognition.” Of course need for cognition is also correlated with general intelligence, since we are less likely to enjoy doing things we find hard. 
Intelligent Views The capacity to think complexly and the enthusiasm for novel and complex ideas is why both intelligence and openness are correlated with secularism (specifically less religious affiliation and fundamentalist beliefs) and political liberalism.   Intelligence and openness also tend to undermine social conformity,  and support analytical modes of thought that undermine dependence on dogmas and orthodoxies. I will discuss openness again in the next essay in relation to the neurological and genetic effects on political ideology and cognitive biases, and again in the essay on transcendence and altered states of consciousness.
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