War is in decline all over the world, as argued in Joshua Goldstein's Winning the War on War.

Judge as of 2011-10-06 using conflict data available then (e.g. UCDP/PRIO armed conflict datasets, Human Security Report, Goldstein's Winning the War on War). True: data up to about 2010–2011 show a clear long-term decline (e.g. since the Cold War peak or since WWII) in the number and/or deaths of wars and armed conflicts worldwide, and the decline is broad across regions, not limited to one area. Mostly true: there is a clear global decline in battle deaths or wars, but one or two regions show stable or rising conflict, so 'all over the world' slightly overstates it. Mixed: some measures (e.g. battle deaths) decline while others (e.g. number of conflicts) do not, or the decline holds only for some timeframes. Mostly false: the decline is real only in a narrow sense (e.g. interstate war only) and most global conflict measures are flat or rising. False: the data show no decline, or a rise, in war worldwide over the relevant period.

Set before the research began.

1. E1 Press Conference on 2009/2010 Human Security Report United Nations Department of Public Information (press release) · 2 December 2010

   “More telling was the fact that “high-intensity wars”, or those that killed at least 1,000 people per year, had declined by 78 per cent since 1988.”

2. E2 Press Conference on 2009/2010 Human Security Report United Nations Department of Public Information (press release) · 2 December 2010

   “Highlighting key findings from the current study, he said that overall, the number and intensity of conflicts had declined since the 1950s, largely due to the end of the Cold War and colonial eras, an increase in the interdependency between nations, and a major increase in the number of democracies worldwide.”

3. E3 Press Conference on 2009/2010 Human Security Report United Nations Department of Public Information (press release) · 2 December 2010

   “While there had been an increase in the overall number of conflicts between 2003 and 2008, he said, it was important to note that this was largely due to an increase in minor conflicts – those that killed very few people.”

4. E4 Armed Conflict, 1989–2003 Journal of Peace Research (Oxford Academic) · September 2004

   “The global number of armed conflicts continued to decline in 2003. A total of 29 conflicts in 22 countries were active in 2003, as against 31 conflicts in 23 countries in 2002. This is the lowest level of armed conflict since the early 1970s.”

The 2009/2010 Human Security Report, as summarised by the UN, found that the overall number and intensity of conflicts had declined since the 1950s (E2), and that high-intensity wars had fallen 78 per cent since 1988 (E1). A Journal of Peace Research article reports that the number of armed conflicts continued to decline in 2003, reaching the lowest level since the early 1970s (E4). However, the total number of conflicts rose between 2003 and 2008, mostly through minor conflicts (E3). None of the evidence breaks the trend down by region, so it does not show that the decline was 'all over the world'. That makes the long-term global decline clear, but the claim's full breadth is overstated.