The Neuroscience of Moral Decisions Philosophical and Legal Implications

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The Neuroscience of Moral DecisionsPhilosophical
and Legal Implications
Joshua Greene, Harvard University Dana Center,
Washington D.C., June 29 2006
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The Liberal Says
Dont blame him. Blame his brain!
Most of the developmental research measures
behaviors, self-perceptions, or attitudes, but
mounting evidence suggests that at least some of
the differences between adults and adolescents
have neuropsychological and neurobiological
underpinnings. --Laurence Steinberg and
Elizabeth Scott (2003) Less Guilty by Reason of
Adolescence
Assumption If your brain is responsible for your
behavior, then you are not.
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The Conservative Says
Dont blame his brain. Blame him!

By locating addiction in the brain, not the
person, the National Institute of Drug Abuse
has generated an unwarranted level of enthusiasm
about pharmacology for drug addiction. --Sally
Satel and Frederick Goodwin (1998) Is Addiction
a Brain Disease?
Assumption If youre still a person, then you
cant blame it all on your brain.
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The Law Says
If hes rational, blame him. If hes not
rational, blame his brain.
Rationality is the touchstone of legal
responsibility. --Stephen Morse (2004) New
Neuroscience, Old Problems
Assumption Rationality is what really matters
for responsibility.
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The Neuroscientist Says
Blame him? Blame his brain?Its all the same!
I am my brain. --Thomas Nagel (1986) The View
from Nowhere
Assumption Whatever responsibility is, its NOT
a matter of blaming you instead of your brain.
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A Case StudyThe Child Molester
Burns and Swerdlow, 2003
Why does brain damage excuse? Moral intuition
(liberal and conservative) The cause is
something external to him--his brain. The Law
Damage compromised his rationality
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A Thought ExperimentTwo Villains
A Normal Villain Same genes Same
experience Same brain/mind Same behavior
Science Project lousy genes lousy
experience criminal mind criminal behavior
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What do we care about?
We want to know whether the bad behavior is
caused by something external to the person, where
the person is a mind or soul distinct from his
brain.
Problem Is there an immaterial mind/soul? How
do we know what it does?
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What Do Souls Do?
Does the soul have a core competence?
?
Yes Moral Judgment
Is there a soul? translates to Is moral
judgment a purely physical process?
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Moral Judgment as a Physical Brain Process
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The Trolley Problem
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The Footbridge Problem
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Personal vs. Impersonal Moral Judgment
Emotion/Social Cognition Areas Cognitive Areas
(Bilateral)
Inferior Parietal Lobe (Bilateral Not shown)
Brain Activity change MR signal
Non-moral Dilemmas
Greene et al., Science, 2001
Impersonal Moral Dilemmas
Greene et al., Science 2001
Personal MoralDilemmas
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The Crying Baby Problem
P.J. Loughran
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Series of Comparisons
Moral Dilemmas
Personal Moral Dilemmas
Impersonal Moral Dilemmas
Difficult Personal Moral Dilemmas
Easy Personal Moral Dilemmas
vs.
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Prediction 1 Cognitive Conflict
Greene et al., Neuron (2004)
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Prediction 2 Cognitive Control
Greene et al., Neuron (2004)
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Series of Comparisons
Moral Dilemmas
Personal Moral Dilemmas
Impersonal Moral Dilemmas
Difficult Personal Moral Dilemmas
Easy Personal Moral Dilemmas
?
?
vs.
Judgment inappropriate
Judgment appropriate
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Prediction 3Utilitarian Cognitive Control
Note a priori ROI matched for RT Same stimuli
(dilemmas)
Greene et al., Neuron (2004)
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Prediction 3Utilitarian Cognitive Control
Response about here (adjusted for lag)
N 39, p lt .005, cluster 8
?
?
Greene et al., Neuron (2004)
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Keeping a Promisevs.The Greater Good
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Keeping a Promisevs.The Greater Good
?
?
N 22, p lt .02, cluster 10
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So What?
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A Dual Process Model
?
cognitive control
?
controlled, conscious cognitive response
?
?
conflict monitor
judgment
stimulus
?
unconscious appraisal
emotional response
?
?
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If we do find the soul
If we dont find the soul
or
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Punishment Without Soul?
Two rationales for punishment
retribution
deterrence
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Pure Deterrence Thinking
Instead of asking Was it really him, or was it
just his brain? Was he really unable to control
himself? Did he really understand what he was
doing? We ask What are the costs/benefits of
punishing people like him? e.g. Will other
mentally disabled people be deterred?
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Pure Deterrence Thinking
Cold and inhuman?
Or super humane?
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To summarize
Were going to be arguing about this stuff for a
long time.
Because the real issue is metaphysical dualism.
The law avoids this issue by focusing on reason,
which is not what people really care about.
If dualism is correct, then we have to find the
magic line between brain and soul.
If dualism is incorrect, then almost everyones
thinking has to change.
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Jonathan Cohen Leigh Nystrom John Darley Kelly
Lowenberg NIH NSF
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