Non-state actors deliberately using powerful new technologies to cause harm could be bad in a number of ways:^[1]

By directly causing the deaths of millions of people
By creating instability and thus compromising humanity’s ability to combat other existential risks
In worst case scenarios, by directly posing an existential risk, via irreparable civilizational collapse or human extinction

But how plausible is it really that non-state actors would cause this much harm?

Crudely, this breaks down into two questions:

How many actors will be capable of committing harm in this way?
How many actors will be willing to commit harm in this way?

Question 1 is about future technologies: how cheap they will be, how easy it will be to access the relevant information, what human and natural resources will be necessary to create them, and how much harm they will be capable of. I don’t have the expertise to say sensible things about this.

Question 2 is about people. I think that to form an overall answer to the question there are a number of different approaches to consider:

Historical approaches: base rates for things like terrorist attacks, mass murders with omnicidal intent, genocides etc; qualitative histories of past omnicidal actors and past uses of dangerous technologies
Security approach: identifying and monitoring actors in the present who seem most worrying from this perspective
Psychological approach: base rates for things like dark triad traits, omnicidal wishes etc
Structural approach: factors which influence the rates of things like terrorist attacks, instability, political violence; and how these factors might change in future

This post doesn’t attempt an overall answer. Instead, it offers one concrete piece of the puzzle: some data on the base rates of terrorist attacks.

For a range of different groups, I’ve pulled together data on the number of attacks per million group members over roughly the last decade. This gives a sense of how common terrorist attacks are, and of how much the rates vary between groups.

In the main post, I discuss a summary table of the main findings. For each of the groups I look at, there’s also a more detailed appendix.

I think information like this helps us think about what rates of terrorism might be like in future, and contributes to getting a better sense of how big the risks from non-state actors are.

Summary table

The table below shows an annual rate of terrorist attacks for various different groups.

The data for terrorist attacks is an average of attacks from 2010-2019 from the Global Terrorism Database.
The data for groups comes from various years and sources. Follow the links for more detailed tables. Hover over the footnotes to see the data source for the group.

Group	Attacks per million	Definition of group
Northern Irish nationalists^[2]	57	Self-reported
Northern Irish unionists^[2]	8	Self-reported
US Muslims^[3]	1.7	-
US radical Muslims^[4]	23	US Muslims who think that suicide bombing is sometimes justified in defense of Islam
UK Muslims^[5]	0.5	-
UK radical Muslims^[6]	12	UK Muslims who have sympathy with suicide bombers
US radical right (see definition)^[7]	0.21	Republicans who think political violence is sometimes justified
US pro-lifers^[8]	0.01	Self-reported pro-lifers
UK right^[9]	0.6	Self-reported right wing people
US radical left (see definition)^[7]	0.04	Democrats who think political violence is sometimes justified
UK left^[9]	0.3	Self-reported left wing people
US environmentalists^[10]	0.01	Self-reported active participants in the environmentalist movement
US vegans^[11]	0.1	-
UK environmentalists^[12]	0.016	People who think the environment is one of the three most important issues facing the country
UK vegans^[13]	0.1	-
The World^[14]	1.45	-
The West^[15]	0.3	Countries included: the EU, UK, Norway, Iceland, Switzerland, US, Canada, Australia, New Zealand.

Discussion

There are some salient problems with these numbers:

The groups aren’t directly comparable to one another. Are Muslims in the UK who think suicide bombings are sometimes justified comparable to vegans in the UK? Or to environmentalists? Are Republicans who think that political violence is sometimes justified comparable to people in the UK who say they are right wing? I would caution against reading this table as a straightforward indication of relative rates of attacks. The tables in the appendices often contain additional categories for each group (e.g. UK vegans but also UK vegetarians, UK green voters etc). If you’re interested, you can play around with these numbers to see how they change the comparative rates.
The selection of groups isn’t random. I picked the groups that were most available to me, in terms of data and prior knowledge.
Often the data sources I’m using for group size aren’t great. Sometimes I couldn’t get data for the right years, and used the closest I could get (earliest 2007). Sometimes the sources are self-reports from a single survey. Sometimes I used a secondary source and didn’t bother to find a more authoritative one.
The Global Terrorism Database (GTD) doesn’t contain all terrorist attacks.^[16]
Terrorism is a social rather than a natural category, and calling someone a terrorist is a political act. The activities involved in terrorism blur into other categories like mass murder, state sponsored violence, guerrilla warfare etc.

But the table does give a rough indication of the base rates for terrorist attacks.

Taking the worldwide average as a starting point, you’re looking at roughly one attack per 700,000 people.

However, it’s unlikely that access to the most dangerous emerging technologies will be uniformly distributed around the world. Exactly how it will be distributed is complicated, but if you think access will be concentrated in richer, more stable countries, then you might want to use the Western base rates instead: that’s roughly one attack per 3,000,000 people. So a bit lower.

I think looking at the rates by smaller groups is also interesting: it gives you a sense of how much the rates vary in subpopulations, which could be useful if you wanted to think about risks from specific future groups. To really understand these numbers, I think you need to have a deeper qualitative understanding of the contexts than I do, and I expect this means that some of the numbers are misleading in ways that I can’t see. That said, I think there are still some minimalist things to note

Among the groups I looked at and according to the numbers I found, the groups with the most attacks were self-reported Northern Irish nationalists, with rates of ~60 per million.^[17] Then came Northern Irish unionists and radical Muslims in the UK and US,^[18] with rates in the low 10s per million. UK Muslims, the US radical right, the UK right, UK and US vegans, and the UK left all had rates below 1 per million. (US Muslims were a bit higher at 1.7.) The US radical left, US pro-lifers and UK and US environmentalists^[19] had rates below 0.1 per million. So the rates among the different groups I looked at vary by around two orders of magnitude.

Another thing worth noting is that terrorist attacks are reasonably rare in all of these groups, even where part of the group definition includes thinking that political/religious violence is sometimes justified. It’s cheaper to talk than to act, and we should expect many, many talkers to every act of terrorism (and millions of innocent bystanders whose ideas have been radicalised in ways they would never condone).

Even when it comes to the actual attacks, most of them are clearly not committed with omnicidal intent. Most terrorist attacks have no fatalities, and it’s plausible that terrorism in general isn’t really about causing lots of deaths.^[20] Groups like al-Qaeda or the IRA have political goals which couldn’t be met if everyone died, and ideologies which genuinely support human extinction are mercifully rare. The rate of terrorist attacks with omnicidal intent must be far lower than the rate of terrorist attacks in general.

But given that there are 8 billion people in the world, the rough rates of terrorist attacks I’ve presented here aren’t exactly reassuring when it comes to risks from non-state actors.

Appendices

There’s a more readable version of these tables here.

Appendix 1: Northern Irish nationalists

Category	Number	Year	Number per million nationalists	Source
Nationalist voters	757,000	Average 2010, 2015, 2017, 2019	1,740,000	Wikipedia [a]
Sympathy with republican violence	566,000	2007	1,300,000	NILT [a]
Nationalists	434,000	Average 2010-2019	1,000,000	NILT [b]
Tomorrow would vote to join ROI	415,000	2016	956,000	Ipsos MORI, p. 6
Pro reunifying with Ireland	331,000	Average 2010-2019	763,000	NILT survey via Wikipedia
A lot of sympathy with republican violence	94,300	2007	217,000	NILT [a]
Republican attacks	24.7	Average 2010-2019	57	GTD

Appendix 2: Northern Irish unionists

Category	Number	Year	Number per million unionists	Source	Notes
Pro remaining in the UK, devolution/direct rule	1,230,000	Average 2010-2019	2,130,000	NILT survey via Wikipedia
Tomorrow would vote to stay in the UK	1,190,000	2016	2,060,000	Ipsos MORI, p. 6
Unionist voters	910,000	Average 2010, 2015, 2017, 2019	1,570,000	Wikipedia [a]
Unionists	578,000	Average 2010-2019	1,000,000	NILT [b]
Sympathy with loyalist violence	547,000	2007	946,000	NILT [a]
Pro remaining in the UK, direct rule	287,000	Average 2010-2019	497,000	NILT survey via Wikipedia
A lot of sympathy with loyalist violence	56,600	2007	97,900	NILT [a]
Marching band members	30,000	2013	51,900	Wikipedia [b]	NB this is ‘an all-time high’
Loyalist paramilitaries	12,500	2020	21,600	BBC	NB CFR thinks it’s only several hundred
Loyalist attacks	4.6	Average 2010-2019	8	GTD

Appendix 3: US Muslims

Category	Number	Year	Number per million Muslims	Sources
Muslims	2,550,000	Average 2007, 2011	1,000,000	Pew Research (a)
Suicide bombing and other forms of violence to defend Islam is sometimes justified	179,000	Average 2007, 2011	70,000	Pew Research (b), p. 2
Suicide bombing and other forms of violence to defend Islam is often justified	25,500	Average 2007, 2011	10,000	Pew Research (b), p. 2
Charged with jihadi terrorism	40	Average 2007, 2011	16	Statista
Attempted to join ISIS	60	One fifth of the cumulative total in 2018	24	NPR
Terrorist incidents	4.2	Average 2010-2019	1.7	GTD
Groups involved	0.2	Average 2010-2019	0.1	GTD

Appendix 4: UK Muslims

Category	Number	Year	Number per million Muslims	Sources	Notes
Muslims	3,230,000	Average 2015-2016	1,000,000	ONS Wikipedia	Slight underestimate because the Scottish data is from 2011.
Sympathy with violence organised by groups to protect their own religion	762,000	2015	236,000	Ipsos MORI, p. 69
Support for establishing a Caliphate	222,000		68,800	Ipsos MORI, p. 69	The survey emphasised that this was ISIS’ goal.
Sympathy for suicide bombing	127,000		39,300	Ipsos MORI, p. 70
Sympathy with people organising radical groups/making threats of terrorist actions/committing terrorist actions	65,700	2016	20,300	Ipsos MORI, p. 70	Sympathy for all three statements came out at 2%.
In custody for terrorism	151	Average 2015-2016	47	UK government
British nationals who have fought in Syria or Iraq	150	One sixth of the cumulative 2019 figure	46	Parliament
Islamist terrorist attacks	1.5	Average 2010-2019	0.5	GTD
Groups involved	0.2	Average 2010-2019	0.1	GTD

Appendix 5: US right

Category	Number	Year	Number per million on the right*	Sources	Notes
Republicans who think political violence is sometimes justified [a]	77,400,000	Average 2017-2021	1,000,000	Washington Post PRRI Statista	Some of the numbers from eyeballing.
Faith and flag conservatives plus populist right [b]	69,700,000	2021	901,000	Pew research
Faith and flag conservatives [c]	33,200,000	2021	429,000	Pew research
Devoted conservatives [d]	20,000,000	2018	258,000	Hidden Tribes
Hate groups	938	Average 2017-2020	12.1	SPLC (a)
Extreme antigovernment groups	571	Average 2019-2020	7.4	SPLC (b)
Militias	175	Average 2019-2020	2.3	SPLC (b)
Terrorist plots	45	Average 2015-2020	0.6	Washington Post
Terrorist attacks and plots	42	Average 2017-2019	0.5	CSIS	Numbers from eyeballing.
Right wing terrorist attacks	16.4	Average 2010-2019	0.2	GTD

* See [a].

[a] The average responses to a few different questions over a few different years:

Do you think it is ever justified for citizens to take violent action against the government, or is it never justified?
True American patriots might have to resort to violence in order to save our country
“feel somewhat justified in using varying levels of violence to achieve their political goals” (my source isn’t reasoning transparent about the questions that build this up)

[b] “Populist Right, who have less formal education than most other typology groups and are among the most likely to live in rural areas, are highly critical of both immigrants and major U.S. corporations.” 11% of the population. Plus [c].

[c] “Faith and Flag Conservatives are intensely conservative in all realms; they are far more likely than all other typology groups to say government policies should support religious values and that compromise in politics is just “selling out on what you believe in.”” 10% of the population.

[d] “Devoted Conservatives (6 percent of the population) are deeply engaged with politics and hold strident, uncompromising views. They feel that America is embattled, and they perceive themselves as the last defenders of traditional values that are under threat.”

Appendix 6: US pro-lifers

Category	Number (average 2010-2019)	Number per million pro-lifers	Sources	Notes
Pro lifers	150,000,000	1,000,000	Gallup	US only.
All violence excluding threats	536	3.6	NAF	Includes things like trespassing, stalking, vandalism, burglary. US and Canada to 2013, then US, Canada and Colombia.
Arson/bombing and attempted	2	0.01		US and Canada to 2013, then US, Canada and Colombia.
Arrests at clinical blockades	1.8	0.01		US and Canada to 2013, then US, Canada and Colombia.
Murders and attempted	1.2	0.01		US only.
Terrorist incidents	1.3	0.01	GTD	US and Canada to 2013, then US, Canada and Colombia.

Appendix 7: UK right

Category	Number	Year	Number per million far right people	Source
Voters for right wing parties [a]	14,400,000	Average 2010, 2015, 2017, 2019	2,500,000	BBC 2010, 2015, 2017, 2019 Wikipedia 2010, 2015, 2017, 2019
Voters for far right parties, inc Brexit parties [b]	1,690,000	Average 2010, 2015, 2017, 2019	292,000
Voters for far right parties, exc Brexit parties [c]	171,000	Average 2010, 2015, 2017, 2019	29,600
Right wing people	5,770,000	2013	1,000,000	Ipsos MORI
Terrorist related convictions	12	Average 2019-2020	2.1	Hope not Hate 2018, 2020, 2021
Terrorist attacks [d]	3.6	Average 2010-2019	0.6	GTD

[a] Voters for the following parties: Conservative, Democratic Unionist Party, Ulster Unionist Party, Ulster Conservatives and Unionists—New Force, Traditional Unionist Voice, Christian Peoples Alliance, UKIP, The Brexit Party, Independence from Europe, English Independence Party, Democratic Nationalist Party, Christian Party, English Democrats, Libertarian, National Front, BNP

[b] Voters for the following parties: UKIP, The Brexit Party, Independence from Europe, English Independence Party, Democratic Nationalist Party, Christian Party, English Democrats, Libertarian, National Front, BNP

[c] Voters for the following parties: English Independence Party, Democratic Nationalist Party, Christian Party, English Democrats, Libertarian, National Front, BNP

[d] I included attacks by: Anti-Muslim extremists (and suspected), Anti-Semitic extremists, English Defense League (EDL), Neo-Nazi extremists, Right-wing extremists, White supremacists/nationalists

Appendix 8: US left

Category	Number	Year	Number per million on the left*	Sources
Democrats who think political violence is sometimes justified [a]	57,500,000	Average 2017-2021	1,000,000	Washington Post PRRI Statista
Progressive left plus outsider left [b]	53,100,000	2021	923,000	Pew research
Progressive left [c]	19,900,000	2021	346,000	Pew research
Progressive activists [d]	26,600,000	2021	463,000	Hidden Tribes
Left wing terrorist attacks [e]	2.2	Average 2010-2019	0.04	GTD

* See [a].

[a] The average responses to a few different questions over a few different years:

Do you think it is ever justified for citizens to take violent action against the government, or is it never justified?
True American patriots might have to resort to violence in order to save our country
“feel somewhat justified in using varying levels of violence to achieve their political goals” (my source isn’t reasoning transparent about the questions that build this up)

[b] “Outsider Left, the youngest typology group, voted overwhelmingly for Joe Biden a year ago and are very liberal in most of their views, but they are deeply frustrated with the political system – including the Democratic Party and its leaders.” 10% of the population. Plus below.

[c] “Progressive Left, the only majority White, non-Hispanic group of Democrats, have very liberal views on virtually every issue and support far-reaching changes to address racial injustice and expand the social safety net.” 6% of the population.

[d] “Progressive Activists (8 percent of the population) are deeply concerned with issues concerning equity, fairness, and America’s direction today. They tend to be more secular, cosmopolitan, and highly engaged with social media.”

[e] I included attacks by the following groups: Anarchists, Anti-Fascist Activists, Anti-Police extremists, Anti-Republican extremists, Anti-Trump extremists (and suspected), Left-wing extremists, Students For Insurrection.

Appendix 9: UK left

Category	Number	Year	Number per million left wing people	Source
Left wing people	5,770,000	2013	1,000,000	Ipsos MORI
Voters for leftist parties [a]	26,800	Average 2010, 2015, 2017, 2019	4640	BBC 2010, 2015, 2017, 2019 Wikipedia 2010, 2015, 2017, 2019
Terrorist attacks [b]	1.8	Average 2010-2019	0.3	GTD

[a] Voters for: Respect-Unity Coalition, Trade Unionist and Socialist Coalition, Scottish Socialist Party, Respect Party, Socialist Labour Party, Workers Party, Class War, Workers Revolutionary Party, Workers Party, Socialist Party, Communist, Socialist Alternative, People before profit

[b] Attacks by: All Coppers Are Bastards (ACAB),Angry Foxes Cell, Anarchists (and suspected), Borderless Solidarity Cell (BSC), Informal Anarchist Federation, Random Anarchists

Appendix 10: US environmentalists

Category	Number	Year	Number per million active environmentalists*	Source	Notes
Protecting the environment should be a top priority for the president and Congress	213,000,000	2020	3,640,000	Pew Research
Environmentalists	136,000,000	2021	2,330,000	Gallup	Self reported
Make an effort to live in ways that protect the environment all the time	62,500,000	2019	1,070,000	Pew Research [b]
Active participant in the environmental movement	58,500,000	Average 2010-2017	1,000,000	Gallup [b]
Vegetarian	9,700,000	2021	166,000	The Vou
Vegan	1,000,000	2021	17,100	The Vou
Ecoterrorism indictments	7.5	Average 2005-2008	0.1	FBI
Terrorist attacks	0.8	Average 2010-2019	0.01	GTD	Including animal rights related attacks.
Groups involved	0.3	Average 2010-2019	0.01	GTD	Including animal rights related attacks.

* Defined as ‘active participants in the environmental movement’, self-reported.

Appendix 11: UK environmentalists

Category	Number	Year	Number per million environmentalists	Source	Notes
Environment affects purchase decisions	28,500,000	Average 2019-2021	1,510,000	YouGov (a)	Self reported
Environment affects donation decisions	23,800,000		1,260,000	YouGov (b)	Self reported
Environment most important issue	18,900,000		1,000,000	YouGov (c)
Environment affects career decisions	15,300,000		808,000	YouGov (d)	Self reported
People who would vote green tomorrow in general election	4,270,000	Average 2019-2021	226,000	YouGov (e) YouGov (f)
Green voters general election	850,000	2019	45,000	Wikipedia
Said they’d go meat free	5,670,000	Average 2019-2021	300,000	Finder (a) Finder (b)
Did go meat free	270,000	Average 2019-2021	14,300	Finder (a) Finder (b)
Vegetarians	4,350,000	Average 2019-2021	231,000	Finder (b)
Pescatarians	2,900,000		154,000
Vegans	1,440,000		76,300
XR mailing list	168,000	Average 2019-2021	8,900	XR
Read XR emails	50,400	2022	2,670	XR	Extrapolating their current open rate
XR protestors	7,000	Average 2019-2021	371	James Ozden, correspondence	This is a rough number of people per year attending an in-person protest. James was an XR member at the time.
XR arrests	1,380	Average 2019-2021	73	Independent Guardian Standard Huffington post	Probably doesn’t include all arrests. James thinks these constitute most of the relevant arrests.
Animal Rebellion arrests	115	Average 2020-2021	6	James Ozden, correspondence	James ran Animal Rebellion at the time, and thinks Animal Rebellion arrests constitute the vast majority of animal rights arrests in the period.
Terrorist incidents	0.3	Average 2010-2019	0.016	GTD	Including animal rights related attacks.
Groups involved	0.4	Average 2010-2019	0.021	GTD	Including animal rights related attacks.

Appendix 12: Worldwide terrorist attacks

Category	Average number 2010-2019	Number per million	Source
Global population	7,340,000,000	1,000,000	Wikipedia
Terrorist attacks	10,600	1.45	GTD

Appendix 13: Western terrorist attacks

Category	Number	Year	Number per million	Sources
Population	906,000,000	Average 2010-2019	1,000,000	World Bank
Terrorist attacks	274	Average 2010-2019	0.30	GTD

Countries included: Australia; Austria; Belgium; Bulgaria; Canada; Croatia; Cyprus; Czech Republic; Denmark; Estonia; Finland; France; Germany; Greece; Hungary; Iceland; Ireland; Italy; Latvia; Lithuania; Luxembourg; Malta; Netherlands; New Zealand; Norway; Poland; Portugal; Romania; Slovak Republic; Slovenia; Spain; Sweden; Switzerland; United States; United Kingdom.

Appendix 14: various terrorism related offences per million

Group/Subgroup	Offence type	Number of offences per million group members	Notes
US Muslims who think suicide bombing and other forms of violence to defend Islam is sometimes justified	Charged with jihadi terrorism	223
US Muslims who think suicide bombing and other forms of violence to defend Islam is often justified	Charged with jihadi terrorism	1569
UK Muslims with sympathy with violence organised by groups to protect their own religion	In custody for terrorism	198
UK Muslims with sympathy for establishing a Caliphate	In custody for terrorism	680
US devoted conservatives	Terrorist plots	2
UK far right voters	Terrorist related convictions	7
US vegetarians	Ecoterrorism indictments	1
US vegans	Ecoterrorism indictments	8
UK vegetarians	XR arrests	317	These aren’t really terrorism related, but give an indication of rates of commitment.
UK vegans		958
UK green voters, 2019 general election		1624
UK vegetarians	Animal Rebellion arrests	26
UK vegans		80
UK green voters, 2019 general election		135

Appendix 15: rates of attacks for Northern Irish unionists and nationalists

Category	Attacks per million	Source
Nationalists	57	NILT [b]
Sympathy with republican violence	44	NILT [a]
A lot of sympathy with republican violence	262	NILT [a]
Unionists	8	NILT [b]
Sympathy with loyalist violence	8	NILT [a]
A lot of sympathy with loyalist violence	81	NILT [a]

The data used for this table is from various years between 2007 and 2019.

^
State actors deliberately causing harm in this way could be bad too, but this post doesn’t address those risks.
^
Northern Ireland Life and Times Survey.
^
Pew Research.
^
Pew Research, p. 2.
^
ONS, Wikipedia.
^
Ipsos MORI, p. 70.
^
Washington Post, PRRI, Statista.
^
Gallup.
^
Ipsos MORI.
^
Gallup.
^
The Vou.
^
YouGov.
^
Finder.
^
Wikipedia.
^
World Bank.
^
Though it probably does contain most of them for this time period. See Our World in Data: “ A valuable resource which also provides impressive accounts of terrorist incidents across the world is the many detailed entries in Wikipedia by year, by region or by country. Using this as a cross-reference with the GTD, we have high confidence in the completeness of global data in recent years.”
^
Maybe this is higher than it should be: you could argue that the correct denominator should actually be Irish nationalists, not Northern Irish nationalists.
^
The numbers for radical US and UK Muslims may also be higher than they should be. As Islamist terrorism is so politicised, it seems likely to me that moderate Muslims are less likely to say that suicide bombing is sometimes justified, than moderate Democrats to say that political violence is sometimes justified, for example. So maybe I’m selecting for a more extreme denominator, which inflates the rates.
^
The rates for environmentalists are drawing on terrorist attacks by animal rights groups as well as environmentalist groups, so arguably the real rates should be even lower. Then again, if I could get numbers for environmentalists who think violence is sometimes justified, that might increase the rates quite a lot.
^
See these posts by Gwern. I’m told Bruce Hoffman’s Inside Terrorism also has good discussion of the motivations and aims of terrorist groups, though I haven’t read it myself.

How big are risks from non-state actors? Base rates for terrorist attacks