Food Prices and Malthusian Economics--Posner's Comment
Becker is right of course that a growing demand for food, resulting from world population growth, relative to supply cannot explain the very steep food-price increases that have occurred since 2006; world food prices are 75 percent higher than they were that year and obviously world population has not grown by that percentage, But I do not take this to be a refutation of Malthus, whose insights have relevance to the modern world.
Malthus argued that if a population is living at the subsistence level, if population increases geometrically (for example, a couple has three children, each of the three children eventually marries and produces three children, and so on) but food production only arithmetically, there will be more people than can be fed, and so population will decline through starvation, disease, or war until a new equilibrium is reached. (Because the population is assumed to be living at the subsistence level, the equilibrium cannot be achieved through higher food prices.) Malthus did not foresee the technological advances that have resulted in a faster rate of increase in the food supply than in the population, or increases in wealth that enable food prices to rise to prevent shortages should demand outrun supply. Nor did he foresee modern contraception technology, or China‚Äôs one-child policy. But given his assumptions, his analysis is sound and it gave Darwin the clue he needed to develop the theory of natural selection. In Malthus's model people kill each other to avoid starvation, and those who do best in the desperate struggle survive--hence survival of the fittest as determined by a competitive process.
As Becker points out, Paul Ehrlich and others predicted in the 1970s (beginning with the first "Earth Day," in 1970) mass starvation as a result of continuing population growth. They were wrong, in part by failing to predict the Green Revolution, which greatly reduced the cost of food production. The situation today is different.
The demand for agricultural products has grown, though not as a result of population growth; instead as a result of increased demand for ethanol and other biofuels, and for food that requires more agricultural acreage to produce. Today, besides people and pigs eating corn, our motor vehicles "eat" corn that has been converted into ethanol. And in China and India, which together contain a third of the world's population, increased wealth has led to an increased demand for meat, in China for beef. Cattle eat corn and other crops and are in turn eaten, but the amount of crops consumed in this process is several times greater than the amount that would be consumed if people ate the crops directly, rather than indirectly by eating vegetarian farm animals. China's consumption of beef, which has been growing rapidly for a number of years, is expected to grow 4 percent this year--yet it will still be only about 15 percent of U.S. beef consumption per capita.
Increased demand for agricultural products should lead to increased supply, but the supply response is limited because of the higher price of gasoline, an important input into food production, and because of scarcity of good agricultural land (in part a result of population growth), which implies an upward-sloping supply curve for food..
The fact that increased demand for agricultural products, and resulting high prices, are due to factors other than growth of population does not make a demand-supply imbalance any the less serious. We may be seeing the beginnings of an attenuated Malthusian response in Egypt, where there have been riots recently over food prices. Egypt is a poor country, and to avoid violence the government has had to increase its food subsidies--making the country poorer and hence more vulnerable to political instability, which could result in an Islamic insurrection. In poor countries today, as in ancient Rome, keeping the urban population happy is the foremost political imperative, because urban riots, especially in a nation's capital, can bring the government down. Urban residents are not farmers, so rising food prices only hurt, and do not help, them. But urban food subsidies immiserate the rural population, and limits on food exports, designed to control domestic food prices, disrupt the international agriculture market.
Our ethanol subsidies, and equivalent policies, such as the European Union's rejection of genetically modified foods, and the wealthy nations' (including the United States') tariffs on agricultural imports, could in principle be abandoned in order to increase the supply of food. But domestic interest-group pressures (which in the United States include the disproportionate influence that Iowa exerts in presidential politics) make reform unlikely.