Science Book Review: Braintrust: What neuroscience tells us about morality

by Patricia S. ChurchlandBrain Trust

Reviewed by Mandy Bekhbat

Where do moral values come from? To date, most moral philosophers have proposed pure reason (e.g. Kant) – reason exempt from emotion and passion – or innate knowledge of basic, universal moral principles (e.g. Plato, Marc Hauser) as a source for moral behavior. In this thought-provoking, data-driven book, neurophilosopher Patricia S. Churchland rejects both camps and proposes an alternative hypothesis on the origins of morality. Her hypothesis takes into account the social aspect of human behavior and its underlying biology. While the author does not believe that science provides an authority on what is moral and what is not, she hopes that understanding what it is that makes humans and other animals social, and why we care about others will lead to more effective ways to cope with social problems.

She begins by noting that the idea of reason detached from emotion as the source of morality ignores the fact that emotions are Mother Nature’s way of dictating how we ought to behave in a social setting. Employing a variety of findings from the fields of neuroscience and cognitive science, Churchland extends the views of David Hume, a naturalist who believed that “moral behavior, though informed by understanding and reflection, is rooted in a deep, widespread, and enduring social motivation.” Churchland poses morality as part of social behavior consisting of two components. The biological component of morality is the urge to be social, a behavior reinforced by the evolutionary benefits of group-living. The cultural aspect of morality depends on our capacity to learn and solve complex problems in a social context. Therefore at the core of morality are social behaviors shaped by four main brain processes: 1) caring for self and others, 2) recognizing others’ state of mind, 3) problem-solving in a social context, 4) social learning.

Churchland adeptly observes that social emotions, values, and behavior have adopted existing mechanisms which serve basic physiological functions. Natural selection has deemed self-preservation as a core value in mammals, and in times of homeostatic need the self-preserving circuitry for homeostasis are swiftly activated through the autonomic nervous system, limbic system, and the brainstem. Along with the activation of these “self-preserving” circuits, a motivational emotion such as fear and unpleasantness is generated. Consequently an appropriate behavioral response is shaped by integrating signals from brainstem-limbic circuitry as well as structures such as the insula and anterior cingulate cortex. In this way the circuitry for self-caring gives rise to the core value of being alive and well. Caring for others is made possible by extending self-preservation to the preservation of kin and kith, through the oxytocin/vasopressin systems. The reward/pain circuits mediate the experience of pain and anxiety when separated from kin, and pleasure when reunited with kin, and thus reinforces the values of social living.

While social living affords many survival benefits it also leads to within-group and inter-group social competition and conflicts. Similar to her presentation of the neural basis for caring, Churchland discusses in-depth the distinct neural mechanisms underlying trust and cooperation, the ability to predict another person’s inner state, imitate another’s behavior, and solve complex problems in a social context. Extremely attentive to details and nuances of the studies cited, Churchland cautions the readers against overgeneralizing and making conclusions unsupported by the data. In the spirit of good scientific writing she emphasizes the importance of delving into hands-on studies in order to derive meaningful insights about how scientific findings help create an explanation for aspects of human behavior.

Braintrust does an excellent job in providing compelling neuroscientific data in order to support her hypothesis on the origins of morality. However, Churchland doesn’t address exactly how understanding the neural underpinnings of morality could guide the reader through moral dilemmas that we face in our contemporary society. For example, the finding that cortical areas important for social interactions such as the insula and the anterior cingulate cortex are smaller/less functionally active in psychopaths only seems to add to the complexity of the question of whether psychopaths should be punishable for their criminal actions. Given her arguments in this book, she would likely say that each moral decision ought to be inferred by carefully weighing all relevant factors and analyzing the situation at hand, rather than deriving what we ought to do from a set of hard-set rules such as Kant’s categorical imperatives.

Such a view is consistent with moral relativism, the idea that different cultures/people have differing ideas of what is right or wrong. Human cultural practices and conventions continuously change as solutions to social problems emerge and evolve. If one is to accept morality as part of social behavior then it follows that morality is relative and that nothing is inherently good or bad. Also consistent with moral relativism is the author’s rejection of innate, universal knowledge of moral conduct as a source of human moral behavior. Researcher Jonathan Haidt proposed that humans make moral decisions by appealing to an innate, universal “moral organ” which allows us to decide what is right or wrong without much deliberation. Churchland thinks that universality of a moral practice such as a preference for truth, is certainly consistent with the idea of innateness. However, she points out, universality of moral values can alternatively be just a good solution to a common social problem much like convergent evolution of the eye is a good solution to sensing the environment. While we do not possess an innate moral organ, she concludes, we can make fairly solid attempts at tackling complex moral questions by analyzing the facts and circumstances, examining our moral intuitions, and understanding of how our brains have evolved to value certain social behaviors and practices.


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