Why your brain might be the real source of your moral compass.
What is the foundation of our morality? For centuries, philosophers have argued that moral values come from divine command, abstract reasoning, or innate philosophical principles. But what if the origins of morality are rooted not in the realms of philosophy or religion, but in the biological structures of our own brains? In her groundbreaking book Braintrust: What Neuroscience Tells Us About Morality, neurophilosophy pioneer Patricia Churchland argues precisely that. She presents a compelling case that morality originates in the neurobiology of attachment and bonding, shaped by evolution and refined by culture 1 .
This provocative perspective suggests that the very fabric of our moral intuitions—our sense of fairness, our capacity for empathy, our commitment to helping others—stems from ancient brain systems that first evolved to ensure the survival of mammalian offspring. At the heart of this story is oxytocin, an ancient neurochemical that plays a crucial role in social bonding, trust, and the circle of caring that extends from family to friends and eventually to strangers 2 .
Churchland's central argument is that morality is a natural phenomenon—"constrained by the forces of natural selection, rooted in neurobiology, shaped by the local ecology, and modified by cultural developments" 2 . She challenges the traditional philosophical approaches that have long dominated moral theory, suggesting instead that we must look to the biological basis of social behavior to understand where our values come from.
The foundation of morality, in Churchland's view, lies in what she calls the "neurobiological platform of bonding" 1 . This platform initially evolved in mammals to support the caring for offspring—a behavior essential for species survival. The same neural circuitry that enables a mother to attend to her child's needs, experience distress at separation, and find pleasure in connection, provides the basic neural architecture upon which human morality is built 7 .
Morality is constrained by natural selection, rooted in neurobiology, and shaped by ecology and culture 2 .
The neurobiological platform of bonding provides the foundation for human morality 1 .
How does the simple biological impulse to care for offspring develop into complex moral systems? Churchland traces this expansion through several key mechanisms:
Churchland aligns with philosopher David Hume in viewing morality as grounded in sentiments rather than pure reason 8 . However, she takes this further by identifying the specific neurobiological components underlying these moral sentiments.
At the heart of Churchland's neurobiological account of morality is oxytocin, a peptide hormone and neurotransmitter that plays a crucial role in social bonding across mammalian species 2 . Oxytocin operates as a key facilitator of the social behaviors that form the foundation of morality.
Churchland emphasizes that oxytocin doesn't work in isolation but functions within what she calls the "oxytocin-vasopressin network," a complex system involving multiple neurochemicals, receptor distributions, and neural pathways throughout the limbic system, brainstem, and prefrontal cortex 2 .
One of the most compelling pieces of evidence for oxytocin's role in social behavior comes from experiments where researchers administered oxytocin via nasal spray to study its effects on trust and cooperation.
Researchers recruited healthy volunteers for the study
Participants received either oxytocin or a placebo via nasal spray
Participants played trust games requiring them to make financial decisions that involved potential cooperation with others
Researchers measured the degree of trust and cooperation displayed by participants
The results were striking: participants who received oxytocin nasal spray showed significantly higher levels of trust and cooperation compared to those who received the placebo 2 . This suggested that oxytocin plays a direct role in facilitating the prosocial behaviors that underlie moral systems.
| Behavior | Effect of Oxytocin | Potential Moral Significance |
|---|---|---|
| Trust in economic games | Increased | Foundation for cooperative societies |
| Maternal bonding | Strengthened | Basis for extended caring |
| Social anxiety | Reduced | Enables wider social connections |
| Wound healing | Accelerated | Physical manifestation of social support benefits |
| Pair bonding | Enhanced | Extends caring beyond offspring |
While oxytocin plays a crucial role, Churchland is careful to place it within a broader neurobiological context. Morality, she argues, depends on multiple interacting brain systems:
Churchland also addresses the question of innate moral principles, expressing skepticism toward strongly nativist views that propose specialized moral modules in the brain 9 . She emphasizes the complexity of gene-behavior relationships and the importance of learning and cultural transmission in shaping our moral intuitions 2 .
Churchland's biological approach to morality has significant implications for philosophical ethics. She argues that the traditional quest for absolute moral rules or a universal ethical system is misguided 2 . Instead, she suggests that moral problem-solving typically occurs through constraint satisfaction rather than deductive reasoning from first principles 8 .
In this view, when we face moral dilemmas, we don't apply rigid rules but rather weigh multiple, sometimes conflicting considerations—much like how our brains process other complex information 8 . This explains why moral concepts cannot be neatly defined with necessary and sufficient conditions, and why moral decision-making often feels messy and intuitive rather than logical and deductive 8 .
Churchland also rejects the idea that morality requires a religious foundation or supernatural source 2 . If moral values are rooted in our neurobiology, they emerge naturally from our identity as social mammals rather than being imposed from outside our natural world.
| Aspect | Traditional Philosophical Views | Churchland's Neurobiological View |
|---|---|---|
| Source of morality | Divine command, abstract reason, innate ideas | Neurobiology of attachment and bonding |
| Primary moral faculty | Reason | Emotion-guided learning with reasoning |
| Moral motivation | Duty, principle | Social attachment, caring |
| Nature of moral concepts | Definable with necessary and sufficient conditions | Messy prototypes learned through experience |
| Moral problem-solving | Deductive reasoning from principles | Constraint satisfaction weighing multiple factors |
Despite its innovative approach, Churchland's theory has drawn criticism from several quarters. Some scholars question whether neuroscience can truly explain moral values, raising Hume's famous is-ought problem—the philosophical challenge of deriving moral prescriptions ("ought") from factual descriptions ("is") 8 .
Some argue that knowing about oxytocin tells us little about how we debate complex moral issues like capital punishment or abortion
Churchland's approach may understate the role of cultural and social factors in shaping morality 2
One review suggests Churchland successfully explains the "how" of morality but falls short on the "why"—why morality evolved the way it did 2
The connection between neurochemical processes and concrete moral decision-making remains ambiguous in many cases
Churchland acknowledges some of these limitations, particularly the current gaps in neuroscientific knowledge 2 . She positions her work as an initial framework for understanding morality naturally rather than as a complete theory.
| Research Tool/Method | Function in Moral Neuroscience Research |
|---|---|
| Oxytocin/Vasopressin nasal spray | Measures effects of neuropeptides on trust and cooperation |
| fMRI (functional Magnetic Resonance Imaging) | Identifies brain regions active during moral decision-making |
| Economic games (Trust Game, Ultimatum Game) | Quantifies social behaviors in controlled laboratory settings |
| Behavioral genetics | Explores heritability of social traits and moral tendencies |
| Lesion studies | Examines how brain damage affects moral judgment |
| Psychophysiological measures | Tracks bodily responses (heart rate, sweating) during moral dilemmas |
Patricia Churchland's Braintrust offers a revolutionary perspective on the age-old question of morality's origins. By rooting moral values in the neurobiology of attachment and bonding, she provides a naturalistic framework that challenges both religious and traditional philosophical accounts.
While the neurobiological approach may not answer every moral question, it provides something potentially more valuable: a scientifically-grounded understanding of how our capacity for morality emerged and developed. This perspective suggests that our moral intuitions are not mysterious revelations or purely rational constructions, but natural capacities that evolved because they enhanced survival and flourishing in highly social species.
As Churchland herself notes, the core of this biological approach isn't entirely new, but her synthesis of data from neuroscience, evolutionary biology, and philosophy offers a fresh perspective on one of humanity's most cherished attributes 2 . The message is both humbling and inspiring: our highest values—our sense of justice, our capacity for compassion, our commitment to others—may be deeply embedded in the very structure and chemistry of our brains.
As research in this field continues to evolve, we can expect even deeper insights into how our biology shapes our morality, potentially offering new ways to understand and enhance human cooperation and social flourishing.