In 1966, Paul Ehrlich visited India to study butterflies. This trip provided a perfect rhetorical device to help his readers imagine the dangers of overpopulation. He was able to describe his firsthand reaction to Delhi:
As we crawled through the city, we entered a crowded slum area.... the streets seemed alive with people. People eating, people washing, people sleeping. People visiting, arguing, and screaming. People thrusting their hands through the taxi window, begging. People defecating and urinating.... People, people, people, people.
Forcing people to look at poverty generates a strong emotional response. For example, many people who go on island vacations are deeply disturbed by the poverty of the local area. These emotional responses can mislead people into underestimating the merits of an increasing human population. Humans are on a hedonic treadmill; they have a tendency to adapt to increasing standards of living. Empathetic people who have adapted to a high income will almost certainly find the poor more disturbing than the poor find each other. Unfortunately, empathy for the poor can backfire if it leads a vacationer to visit a wealthier island or if, as in Ehrlich's case, it helps spur a life-long struggle against humanity.
Viewing poverty makes us uncomfortable, and so we look away. Interestingly, poverty and famine aren't even pictured on Paul Ehrlich's Wikipedia page. His page contains a striking crowd scene from China. However, it isn't a picture of the poor and suffering; it's a picture of people trying to see the Olympic torch.
Our reaction to pictures are based on the average wellbeing of those depicted. A picture of two joyful people can be just as pleasing as a joyous crowd scene. Consider the following chart summarizing the populations of two countries. Now imagine random pictures taken in these countries.
The average picture of country B will be depressing and might lead to the view that overpopulation is a problem. Well-meaning people might think that country B should aspire to be more like country A. Compared to country A, however, country B has more of every possible type of person. It has both more ecstatic people and more content people. The people in the lowest category are still better alive than dead; we shouldn't wish them away.
Although fears of overpopulation have subsided since the publication of The Population Bomb, the view that there are too many people is alive and well. For example, overpopulation is the spiritual villain of Dan Brown's latest novel, Inferno. Many environmentalists link overpopulation to ills like global warming. If increased temperatures become palpable to the average person, overpopulation fears could make a strong resurgence.
HT: Matthew Connelly's Fatal Misconception for the Ehrlich lead.