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What Part of the Brain is Responsible for Moral Reasoning?

PS2007's picture

What Part of the Brain is Responsible for Moral Reasoning?


            I read a really interesting article last year in the New York Times that researchers were finding more and more evidence that there is a specific part of the brain that is active when we are trying to decide a moral dilemma.  They discovered that when this area, or areas around it suffered from damage it affected moral decision making (1).  I found this article really interesting because how we view ourselves has humans has a lot to do with morality; it is partly how we separate ourselves from animals.  The idea of a neurological basis for moral reasoning brought up a lot of questions for me.  If we cannot control our morals, how can criminals be blamed for their actions?  How can anyone be held responsible or praised for their actions if they are just doing what they are programmed to do?  The answers to these questions will be debated until we know a lot more about the brain, but I think the implications are fascinating. 

            The study I referenced earlier was published in 2007 by researchers from the University of Iowa, the University of South California and the California Institute of Technology.  They found that damage to the brain behind the forehead transforms the way people make moral judgments in life-or-death situations.  This area is called the ventromedial area and can become damaged from aneurysms or tumors.  People with this injury are talkative and intelligent, but can be socially awkward.  Researchers found that people with this injury expressed increased willingness to kill or harm another person if doing so would save others' lives.  The New York Times notes that, “The findings are the most direct evidence to date that humans’ native revulsion for hurting others relies on a part of neural anatomy, one that likely evolved before the brain regions responsible for analysis and planning.”  This means that being compassionate and empathetic may be hardwired into our brains (1). 

            Another scientific theory that tries to explain our feelings of empathy involves mirror neurons.  These are a type of brain cell that respond the same whether we perform an action or we watch someone else perform an action.  Neuroscientist Jean Decety hypothesized that these cells and the emotions that they cause were a key step forward in the evolution of social behavior and morality.  Researchers were able to prove that these neurons existed in monkeys, but they have not yet been able to establish their existence in humans (2).

            Jonathan Cohen, a cognitive neuroscientist, discovered other evidence that respect for the human life is innate.  Cohen used an MRI to examine people’s brains when posed with a moral dilemma that caused them to think about killing another human being to save several.  The experiment showed activity in the media parts of the frontal lobe, the dorsolateral parts of the frontal lobe, and the anterior cingulated cortex.  The brain scans also showed conflict between an urge coming from one part of the brain and an advisory coming from another.  The researchers hypothesized that this was conflict between the emotional parts of the brain and the rational ones (3). 

Although we may not yet be able to pinpoint exactly what part of the brain is involved in moral reasoning, we have come a long way in understanding our most basic emotions.  It is kind of nice to believe that all humans find the idea of hurting another person terrible, and that the people who are able to carry out these horrific acts are only able to do so because of a brain malfunction.  It is also interesting to think about the effects these studies may have on our legal system.  Jurors have reduced sentences based on brain imaging results, and this research could help provide evidence for insanity defenses for all murderers.  I think the main question these studies bring up is how difficult is it for humans to overcome our innate impulses—or lack thereof?  How much of our behavior is determined by the structure of our brain?  It may be a long time before we know the answers to these questions but neuroscience research will keep us questioning human nature until we do. 

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Zoe Fuller-Young's picture

Normal Morality

On a similar note, what is found of similar moralities? What I mean is, is there a set of ethical behavior that is found in most people? Or is it always cultural, i.e. how our brain is shaped throughout our lives and what we come to expect as morality from others and ourselves? I find this information about morality interesting with concerns to the "I-Function." Is this the part of the brain that is the home of the "I-Function," along with other responsibilities? Or, is morality simply a small portion of the "I-Function?"
Paul Grobstein's picture

neuroethics, morality

If Emily is right, then it is indeed going to turn out that ethical and moral judgements, indeed ethics and morality itself, is a function of the brain. And varies in different people? So what follows from this? Is there a new picture of "human nature" emerging, and what would it look like.

For some more explorations along these lines, see

See also