The mission of the Arithmetic of Compassion Website is to raise awareness of psychological obstacles to compassion, including psychic numbingpseudoinefficacy, and the prominence effect.

We believe that by raising awareness of these phenomena we can lessen the impact they have on our humanitarian decision making. We provide suggestions for how you can take action to combat these cognitive biases and tackle problems like mass atrocities, famine, climate change, and other critical issues.

A famous saying goes, “One death is a tragedy; a million deaths is a statistic.”

Due to psychic numbing, our sympathy for suffering and loss declines precipitously when we are presented with increasing numbers of victims.

Research has shown that compassion fade can begin to occur when a threat to a single person expands to as few as two people.

Saving one life is of utmost importance, but saving 1 + 1 lives feels less important than saving two lives and sometimes less important than saving one.

Confronting this peculiar “arithmetic of compassion” in our daily lives and our national policy decisions is of critical importance in a world facing catastrophic threats from violence, disease, poverty, and natural disasters.

Click on the links below to learn about three related cognitive biases or visit our Take Action page to learn how you can combat these obstacles to compassion. Our Stories page connects these concepts to current events.

Why do we respond to the needs of "the one," but not of "the many"? 

Why do we lose interest in helping if we can't help everyone?

What prevents us from acting in the face of mass atrocities? 


The Arithmetic of Compassion Website is supported by Decision Research, a nonprofit research institute that investigates decision making.

About the banner image

The Kigali Memorial Centre contains this gallery of photographs depicting victims of the Rwandan genocide. The remains of 250,000 victims are interred at the center. Photo by Radu Sigheti