In the 20th century, at least 170 million people - and perhaps as many as 360 million - have been murdered by their own governments. This is more than four times the approximately 42 million deaths from civil and international wars. 1 The Union of Soviet Socialist Republics, the People's Republic of China and Nazi Germany killed on an appalling scale. But state-sponsored murder also is quite common elsewhere. When the state murders some of its general population, it is called democide; when it murders minorities, the term is genocide.

Authoritarian states employ democide to maintain power. It is part of a broader program of state-approved terror designed to intimidate, demoralize or subjugate the citizenry. Terror has an obvious chilling effect on actual or potential enemies, and it raises the cost of opposition.

Democide has been employed to enforce ideologies (as in the Spanish Inquisition, the Cultural Revolution in China and Muslim fundamentalist states) 2and policies (as in the liquidation of the Kulaks to facilitate Soviet collectivization) 3 . It is not always successful in the long run, as illustrated by the collapse of socialist dictatorships in Eastern Europe and the Soviet Union and the end of the Marcos regime in the Philippines. But it often succeeds for a time, as it has in China, Cuba, North Korea, Pinochet's Chile, Haiti, Iraq, Libya and a number of other African nations.

Genocide typically is directed at a group identified by race, religion, ethnicity or tribe. 4It has occurred in environments as diverse as Germany, the Soviet Union, Bosnia, Burundi, Rwanda, Paraguay, Iraq, Bangladesh, India and Pakistan.

Murder is the most extreme expression of enmity. It may be spontaneous, as dominant group members massacre other groups, or it may be very well planned. This study is concerned only with the mass killings practiced by governments: democide, including genocide.

For example, the study does not include the approximately 3,400 lynchings of Negroes, mainly in the U.S. South, between 1882 and 1935; the 52 people killed in the Los Angeles riot of 1992, the worst in U.S. history; or even the large-scale killings of Muslims and Hindus in the early days of India's independence. Nor does it include civilian casualties of war. It does include deaths from democide and genocide during wartime.

Table I demonstrates that democide occurs mainly in authoritarian regimes. 5 Democracies have not always been averse to democide, but they have usually inflicted it on colonial populations. Democracies account for about 1 percent of the total deaths. The vast majority of 20th-century killing has been done by Communist regimes. 6All Communist states have committed democide and about one-fourth have practiced genocide. Numerically, the Soviet Union and China had the highest levels of killing.

• The Soviet Union killed 54.7 million between 1917 and 1987.

• China killed 35.6 million between 1949 and 1987.

• The Khmer Rouge killed a much larger percentage of its nation's people, liquidating about a third of all Cambodians between 1975 and 1979.

Authoritarian regimes and noncommunist totalitarian governments committed a third of the murders. Overall, about a third of noncommunist nations have practiced democide or genocide since World War II. This includes more than a third of the African states, such as Sudan, Uganda, Nigeria and Rwanda, which killed about half a million of its citizens in 1994. Fifteen South and Central American countries are represented, with Brazil, Guatemala and Colombia killing on a large scale. In Asia and the Middle East, 13 nations have committed democide, Pakistan and Indonesia most extensively. In Europe, besides Nazi Germany, state-sponsored murder has occurred in Cyprus, France (mainly during the German occupation), Greece, Italy (during the fascist period), Spain, Turkey (mainly against the Armenians, but also the Kurds) and the United Kingdom (Ireland, Northern Ireland).

A rough negative correlation exists between the level of state killing and real gross domestic product (GDP) per capita. For example, the Central and South American nations that have modest levels of democide have higher income levels than many of the African and Asian nations that have killed on a larger scale. This suggests that where per capita income is low, life is viewed by the authorities as cheap. Where per capita income is higher, states may be constrained by the cost of killing their populations.

This suggests that "price", measured as output per person, may restrict the amount of state-sponsored murder. A rational dictator or ruling group will practice democide or genocide up to the point at which the marginal benefit equals the marginal cost. In other words, the dictator or ruling group will weigh the incremental benefit of continued rule and a share in the "rents" that are generated through centralized political and economic control (plus any "pleasure" obtained from inflicting terror) against the "cost" - the incremental national output lost from the killing. 7

Civilized people view government-sponsored murder as demented, the murderers as sociopaths. But many aspects of life that are immoral are nevertheless explicable by the amoral apparatus of supply and demand. To explore the relationship between democide and demand, one can estimate a crude demand function illustrating the relationship between the quantity demanded and the price. This study takes the midyear of the period over which democide occurred and obtains the value of the real GDP per capita (in 1985 dollars) for that year. 8 The sample comprises 31 nations which killed 10,000 or more of their citizens and for which real per capita GDP figures were available. 8

The result is a highly significant association: the higher the productivity, the lower the democide level. There is an inverse relationship between the amount of state-sponsored killing of the domestic population and the "value" of the people being killed. A 1 percent increase in real GDP "buys" about a 1.4 percent decline in democide. The estimated demand function for democide is shown in Figure I.

There is also some evidence that democidal governments in higher per capita income nations exercise some self-restraint. This may even help our understanding of the slowdown in the pace of state killings that occurred in the Soviet Union and China. During the Stalin era in the Soviet Union (1929-53), about 42.7 million people were murdered by the state. About 8.1 million were killed in the 34-year period after Stalin (1954-87). While the latter number is still large, Stalin's pace of killing would have resulted in 63.5 million deaths. Despite the poor performance of socialism, the Soviet Union had experienced economic growth. Comrades were increasingly expensive to liquidate. Thus the decreased rate of killing seems attributable to economics rather than to any civility of the post-Stalin Communist leadership.

The 28-year rule of Mao Tse-tung in China (1949-76) yielded 34.4 million killed. In the post-Mao era (1977-87), characterized by rapid economic growth, 874,000 were killed. Again, the slowdown in the rate of murder may be due to the economic fact that the population was more productive and thus more valuable.