Philosophers and social scientists have frequently noted the propensity of humans to commit violent acts not only as individuals but as groups. The twentieth century is a legacy of the ability of humanity to engage willingly in acts of warfare and atrocity.

The study of mass killing

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Since the 19th century various historians have investigated the number of deaths that could be attributed to warfare or ideology. In the 20th century Joel David Singer and Melvin Small analyzed conflicts and Singer argued in The Wages of War, that a conflict with a particular death toll is statistically related to time of events. In recent years there has been an increasing belief among those who study conflict and fatalities related to it, that civil wars in particular are related to measurable economic phenomenon, and the scale of conflict is related to the reach of these factors.

Several researchers have adopted the term democide to refer to fatalities caused by government intention, calling it "murder by government", and they argue that wars should be included with genocide among totals of deaths caused by government action. Others, such as Gregory H. Stanton have adopted the term politicide. He argues that there are eight distinct phases to genocide or other mass killing: Classification, Symbolization, Dehumanization, Organization, Polarization, Preparation, Extermination and Denial. What he labels "Stage 7" conflicts are those with active killing, but that conflicts can cycle through Polarization, Preparation and Extermination repeatedly. His organization tracks killings since 1945 ^*.

The field of Peace studies has been the source for continuing work on deaths because of conflict or other state decision. Marxist historian Eric Hobsbawm in The Age of Extremes: A History of the World, 1914– 1991 (1994) wrote that 187 million people died in the "short 20th century" because of what he termed "government decision". Robert McNamara published a 1991 paper entitled "The Post-Cold War World: Implications for Military Expenditure in the Developing Countries" which estimated 40 million deaths in the developing economies since World War II.

Estimates of mass killings

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Milton Leitenberg's estimate

Milton Leitenberg, of the Center for International and Security Studies, published a 2003 paper which focused on the post war era, and gave very detailed estimates for all major conflicts between 1945 and 2000. His estimate for the total century is based on the following numbers:

• World War I mortality, between 13 and 15 million.
• The Armenian Genocide of 1915, 1 million
• The Russian civil war of 1918–1922 and the Polish-Soviet conflict towards its end, deaths of over 12.5 million in Russia alone.
• The Chaco War, between Paraguay and Bolivia, 1928–1933, approximately 3 million deaths.
• The Spanish Civil War, 1936–1939, 600,000 deaths.
• Various colonial wars, approximately 1.5 million deaths.
• World War II, deaths of between 50 and 60 million.
• Wars/conflicts between 1945 and 2000, deaths of 40 million.
• Soviet collectivization and "dekulakization" 16 million to 50 million, though some included in World War II totals in these estimates.
• Deaths under Mao, between 16 million and 30 million.

Adding in a variety of other pogroms and civil wars, he comes to a final estimate of 216 million. This does not include what he calls "structural violence": deaths in under-developed nations because of crime, poverty, environmental degradation, disease, malnutrition not part of famine, contaminated water and lack of available medicine. He estimates that this reached 17 or 18 million per year by 2000.

Matthew White's estimate

Matthew White has conducted a study, based on figures quoted from a number of divergent and reliable sources to arrive at a conservative estimate of nearly 170 million lives lost to war and major atrocities in the last century. Because fatality statistics are subject to a great deal of uncertainty in turbulent times, White has opted to conservatism in his reporting of statistics. He also employs a commonly-used statistical strategem which forces extreme values at the upper and lower ends of the data field to cancel each other out, resulting in a value closer to the probable mean.

Using existing data, White categorizes these twentieth century events according to most reliable fatality data. While "minor" atrocities and civil conflicts will add to the number, this table compiles those conflicts whose death tolls are close to or exceed half a million souls.

Major mass killings of the Twentieth Century

Rank	Deaths	Event	Time Frame
1	50 000 000	World War II	1937-1945
2	40 000 000	China: Mao Zedong's regime	1949-1976
3	20 000 000	USSR: Stalin's regime	1924-1953
4	15 000 000	World War I	1914-1918
5	8 800 000	Russian Civil War	1918-1921
6	4 000 000	China: Warlord & Nationalist Era	1917-1937
7	3 000 000	Congo Free State	1900-1908
8	2 800 000	Korean War	1950-1953
9	2 700 000	2nd Indochina War (incl. Laos & Cambodia)	1960-1975
10	2 500 000	Chinese Civil War	1945-1949
11	2 100 000	Expulsion of Germans after World War II	1945-1947
12	1 900 000	Second Sudanese Civil War	1983-1999
13	1 700 000	Congolese Civil War	1998-1999
13	1 500 000	Turkish Genocide against Armenia	1915-1923
14	1 000 000	Cambodia: Khmer Rouge regime	1975-1979
15	1 400 000	Afghanistan Civil War	1980-1999
15	1 400 000	Ethiopian Civil Wars	1962-1992
17	1 250 000	Mexican Revolution	1910-1920
18	1 250 000	East Pakistan massacres	1971
19	1 000 000	Iran-Iraq War	1980-1988
19	1 000 000	Nigeria: Biafra	1967-1970
21	800 000	Mozambique Civil War	1976-1992
21	800 000	Rwanda	1994
23	675 000	French-Algerian War	1954-1962
24	600 000	First Indochina War	1945-1954
24	600 000	Angolan Civil War	1975-1994
26	500 000	Indonesia: Massacre of Communists	1965-1967
26	500 000	India-Pakistan Partition	1947
26	500 000	First Sudanese Civil War	1955-1972
26	500 000	Amazonian Indian decline	1900-1999
30	365 000	Spanish Civil War	1936-1939
??	>350 000	Somalia	1991-1999
??	>400 000	North Korean Communist regime	1948-1999

These figures are subject to the usual margins of error. They also include a number of collateral fatalities: civilian casualties of war, democide, famine, and other hardships caused by the social and economic disruption which results from large-scale conflict. For conflicts which began before 1900 or ended after 1999, only those deaths within the 20th century are included.

See also

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• List of wars and disasters by death toll.

External links

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• Twentieth Century Atlas - Top-ranked Atrocities
• [http://www.hawaii.edu/powerkills/ University of Hawaii, professor RJ Rummels page on Freedom,

Democracy, Peace; Power,Democide, and War]

Disaster lists | Violence | 20th century