The Molecule of More

A runaway train hurtles down the tracks toward a group of five workers. 
If nothing is done, they will all die. It’s possible, however, to stop the train 
by pushing a bystander onto the tracks. His death will slow down the train 
enough to save the five workers. Would you push the bystander onto the tracks?
In this scenario, most people would be unable to push the bystander 
onto the tracks—unable to kill a person with their own hands even to 
save the lives of five other people. The H&N neurotransmitters in play 
are responsible for generating empathy for others and will overwhelm 
dopamine’s calculated reason in most people. The H&N reaction is so 
strong in this situation because we’re so close, right in the peripersonal 
zone. We would have to actually put our hands on the victim as we 
send him to his death. That would be impossible for all but the most 
detached person.
But since H&N’s strongest influence is in the peripersonal space—in 
the immediate realm of what the five senses tell us—what would happen 
if we moved back, one step at a time, incrementally diminishing H&N’s 
influence on our decision? Does our willingness—our ability—to trade 

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one life for five increase as we get literally farther away from our victim, 
as we move out of the H&N peripersonal space into the dopaminergic 
extrapersonal?
Start by eliminating the H&N sensation of physical contact. Imag-
ine you’re standing some distance away watching the scene unfold. 
There’s a switch you can pull that will divert the train from the track 
with five people on it to a track that will kill only one. Do nothing, and 
the five will die. Will you throw the switch?
Pull back farther. Imagine you are sitting at a desk in a different city 
on the other side of the country. The phone rings and a frantic railway 
worker describes the situation. From your desk you control the path of
the train. You can activate a switch and divert the train to a track with 
only one person on it, or do nothing and allow the train to hit the five 
people. Will you throw the switch?
Finally, make the situation as abstract as possible: squeeze out all 
the H&N and make it purely dopaminergic. Imagine that you are a 
transportation systems engineer, designing the safety features of the 
railway track. Cameras have been installed by the side of the tracks to 
provide information about who is standing where. You have the oppor-
tunity to write a computer program that will control the switch. The 
program will use the camera information to choose which track will kill 
the fewest people. Will you write the software that in the future might 
save five people by killing one?
The scenarios change but the outcomes will be the same: one life 
is sacrificed so that five can be saved, or five lives are lost to avoid the 
direct killing of one person. Very few people would put their hands on 
an innocent person’s back and push him to his death. Yet very few peo-
ple would hesitate to write the software that would manage the track 
switches in a way that minimizes loss of life. It’s almost as if there were 
two separate minds evaluating the situation. One mind is rational, mak-
ing decisions based on reason alone. The other is empathic, unable to 
kill a man, regardless of the big-picture outcome. One seeks to domi-
nate the situation by imposing control to maximize the number of lives 
saved; the other does not. Whether a person chooses one outcome or 
the other partly depends on activity within the dopamine circuits.

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THE MOLECULE OF MORE
HARD DECISIONS IN THE REAL WORLD
This problem is more than just theoretical; it confronts developers of
self-driving cars. If a fatal crash between two cars is inevitable, what 
should the self-driving car be programmed to do? Should it swerve in 
one direction to protect the life of its owner, or should it swerve in the 
opposite direction, killing its owner, if fewer people in the other car will 
die? Consumer tip: If you’re in the market for a self-driving car, ask the 
salesperson how it’s been programmed.
Another example of the problem was depicted in the 2016 film Eye 
in the Sky. Terrorists in Kenya are preparing two suicide bombers for an 
attack that will kill as many as two hundred people. There’s very little 
time to stop them. On the other side of the world, the remote pilot of
a drone is poised to launch a missile to kill the terrorists. Just before 
he fires, a young girl sets up a table to sell bread next to the terrorists’ 
house. If the drone pilot does nothing, hundreds will die. But to save 
those lives, he must kill the little girl along with the terrorists. The film 
documents the intense debate over which choice to make in this realis-
tic portrayal of the “trolley problem.”
Sometimes we act one way: cold, calculating, seeking to dominate 
the environment for future gain. Sometimes we act another: warm, 
empathic, sharing what we have for the present joy of making others 
happy. Dopamine control circuits and H&N circuits work in opposition, 
creating a balance that allows us to be humane toward others, while 
safeguarding our own survival. Since balance is essential, the brain 
often wires circuits in opposition. It works so well that sometimes there 
is even opposition wired into the same neurotransmitter system. The 
dopamine system operates in this way, so what happens when dopa-
mine opposes dopamine?
THE RADISHES-AND-COOKIES CHALLENGE
The neurotransmitter dopamine is the source of desire (via the desire 
circuit) and tenacity (via the control circuit); the passion that points the 

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way and the willpower that gets us there. Usually the two work together, 
but when desire fixates on things that will bring us harm in the long 
run—a third piece of cake, an extramarital affair, or an IV injection of
heroin—dopaminergic willpower turns around, and does battle with its 
companion circuit.
Willpower isn’t the only tool control dopamine has in its arsenal 
when it needs to oppose desire. It can also use planning, strategy, and 
abstraction, such as the ability to imagine the long-term consequences 
of alternate choices. But when we need to resist harmful urges, will-
power is the tool we reach for first. As it turns out, that might not be 
such a good idea. Willpower can help an alcoholic say no to a drink 
once, but it’s probably not going to work if he has to say no over and 
over again for months or years. Willpower is like a muscle. It becomes 
fatigued with use, and after a fairly short period of time, it gives out. 
One of the best experiments that demonstrated the limits of willpower 
was the famous radishes-and-cookies study. This study relied on decep-
tion. Volunteers were told that they were signing up for a food-tasting 
study. Here is how one scientist described it:
The laboratory room was carefully set up before participants in the food 
conditions arrived. Chocolate chip cookies were baked in the room in a small 
oven, and, as a result, the laboratory was filled with the delicious aroma of
fresh chocolate and baking. Two foods were displayed on the table at which 
the participant was seated. One display consisted of a stack of chocolate 
chip cookies augmented by some chocolate candies. The other consisted of a 
bowl of red and white radishes.
When the participants arrived, they were hungry. They had been told 
to skip a meal before coming to the laboratory. The sight and smell 
of the freshly baked chocolate chip cookies were very tempting under 
these conditions. One at a time the participants were ushered into the 
laboratory where the chocolate chip cookies had just come out of the 
oven, and they were told to sample two or three cookies or two or three 
radishes, depending on which group they had been assigned to. Before 

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the participant began to eat, the scientist left the room, reminding the