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imagine you're watching a runaway
trolley barreling down the tracks
straight towards five workers who can't
escape you happen to be standing next to
a switch that will divert the trolley
onto a second track here's the problem
that track has a worker on it too but
just one what do you do do you sacrifice
one person to save five this is the
trolley problem a version of an ethical
dilemma that philosopher Philippa foot
devised in 1967 it's popular because it
forces us to think about how to choose
when there are no good choices do we
pick the action with the best outcome or
stick to a moral code that prohibits
causing someone's death in one survey
about 90% of respondents said that it's
okay to flip the switch letting one
worker die to save five and other
studies including a virtual reality
simulation of the dilemma have found
similar results these judgments are
consistent with the philosophical
principle of utilitarianism which argues
that the morally correct decision is the
one that maximizes well-being for the
greatest number of people the five lives
outweigh one even if achieving that
outcome requires condemning someone to
death but people don't always take the
utilitarian view which we can see by
changing the trolley problem a bit this
time you're standing on a bridge over
the track as the runaway trolley
approaches now there's no second track
but there is a very large man on the
bridge next to you if you push him over
his body will stop the trolley saving
the five workers but he'll die to
utilitarians
the decision is exactly the same lose
one life to save five but in this case
only about 10% of people say that it's
okay to throw the man onto the tracks
our instincts tell us that deliberately
causing someone's death is different
than allowing them to die as collateral
damage
it just feels wrong for reasons that are
hard to explain this intersection
between ethics and psychology is what's
so interesting about the trolley problem
the dilemma and its many variations
reveal that what we think is right or
wrong depends on factors other than a
logical weighing of the pros and cons
for example men are more likely than
women to say it's okay to push the man
over the bridge so are people who watch
a comedy clip before doing the thought
experiment and in one virtual reality
study people were more willing to
sacrifice men than women researchers
have studied the brain activity of
people thinking through the classic and
bridge versions both scenarios activate
areas of the brain involved in conscious
decision making and emotional responses
but in the bridge version the emotional
response is much stronger so is activity
in an area of the brain associated with
processing internal conflict why the
difference one explanation is that
pushing someone to their death feels
more personal activating an emotional
aversion to killing another person but
we feel conflicted because we know it's
still the logical choice
trolley ology has been criticized by
some philosophers and psychologists they
argue that it doesn't reveal anything
because its premise is so unrealistic
that study participants don't take it
seriously but new technology is making
this kind of ethical analysis more
important than ever for example
driverless cars may have to handle
choices like causing a small accident to
prevent a larger one meanwhile
governments are researching autonomous
military drones that could wind up
making decisions of whether they'll risk
civilian casualties to attack a
high-value target if we want these
actions to be ethical we have to decide
in advance how to value human life and
judge the greater good so researchers
who study autonomous systems are
collaborating with philosophers to
address a complex problem of programming
ethics into machines
which goes to show that even
hypothetical dilemmas can wind up on a
collision course with the real world
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