Existential risks from a

Thomist Christian

perspective

 Stefan Riedener

Global Priorities Institute | January 2021

GPI Working Paper No . 1-2021

Existential risks
from a Thomist Christian perspective
Stefan Riedener, University of Zurich
1 Introduction
Let’s say with Nick Bostrom that an ‘existential risk’ (or ‘x-risk’) is a risk that
‘threatens the premature extinction of Earth-originating intelligent life or the
permanent and drastic destruction of its potential for desirable future develop-
ment’ (2013, 15). There are a number of such risks: nuclear wars, developments
in biotechnology or artiﬁcial intelligence, climate change, pandemics, supervol-
canos, asteroids, and so on (see e.g. Bostrom and Ćirković 2008). So the future
might bring
Extinction : We die out this century.
In fact, Extinction may be more likely than most of us think. In an informal
poll, risk experts reckoned that we’ll die out this century with a 19% probability
(Sandberg and Bostrom 2008). The Stern Review on the Economics of Climate
Change, commissioned by the UK government, assumed a 9.5% likelihood of
our dying out in the next 100 years (UK Treasury 2006). And a recent report
by the Global Challenges Foundation suggests that climate change, nuclear war
andartiﬁcialintelligencealonemightultimatelyresultinextinctionwithaprob-
ability of between 5% and 10% (Pamlin and Armstrong 2015).1But the future
needn’t be so grim. It may also bring
Survival : We survive for another billion years, and on average there
are always 10 billion people, who live very good 100-year-long lives.
So there are 100 million billion future people with very good lives.
This may sound optimistic. But it’s also possible. The earth seems to remain
sustainably inhabitable by at least 10 billion people (United Nations 2001, 30),
and for another 1.75 billion years (Rushby et al. 2013). The quality of our lives
seems to have increased continuously (see e.g. the data collected in Pinker 2018),
and it seems possible for this trend to continue. Notably, it partly depends on us
1More precisely, the report distinguishes between ‘inﬁnite impact’, ‘where civilisation col-
lapses to a state of great suﬀering and does not recover, or a situation where all human life
ends’, and an ‘inﬁnite impact threshold’, ‘an impact that can trigger a chain of events that
could result ﬁrst in a civilisation collapse, and then later result in an inﬁnite impact’ (2015,
40). The above numbers are their estimates for inﬁnite impact thresholds.
1
whether Extinction or Survival will materialise. In fact it may depend on what
we dotoday. We could now promote academic research on x-risks (Bostrom and
Ćirković 2008), global political measures for peace, sustainability or AI safety
(Cave and ÓhÉigeartaigh 2019), the development of asteroid defence systems
(Bucknam and Gold 2008), shelters (Hanson 2008), risk-proof food technologies
(Denkenberger and Pearce 2015), and so on. And while none of these measures
will bring x-risks down to zero, they’ll arguably at least reduce them. So all of
this raises a very real practical question. How important is it, morally speaking,
that we now take measures to make Survival more likely?
The answer depends on the correct moral theory. It’s most straightforward
on standard utilitarianism. Suppose we increase the probability of Survival
over Extinction by just 1 millionth of a percentage point. In terms of overall
expected welfare (setting nonhuman sentience aside), this is equivalent to sav-
ing about 1 billionlives, with certainty. So according to utilitarianism, even
such tiny increases in probability are astronomically important. Indeed, Nick
Bostrom suggested that x-risk reduction ‘has such high utility that standard
utilitarians ought to focus alltheir eﬀorts on it’ (2003, 308ﬀ.; see also Parﬁt
1984, 452f., Beckstead 2013). But this implication isn’t restricted to utilitar-
ianism. Something very similar will emerge on any view that assigns weight
to expected impartial welfare increases. Consider Eﬀective Altruism (or ‘EA’).
Eﬀective Altruism is the project of using evidence and reasoning to determine
how we can do the most good, and taking action on this basis (see MacAskill
2015). This doesn’t presuppose any speciﬁc moral theory about what the ‘good’
is, or about what other reasons we have beyond doing the most good. But Ef-
fective Altruists typically give considerable weight to impartial expected welfare
considerations. And as long as we do, the utilitarian rationale will loom large.
Thus according to a 2018 survey, EA-leaders consider measures targeted at the
far future (e.g. x-risk reduction) 33 times more eﬀective than measures targeted
at poverty reduction (Wiblin and Lempel 2018). The EA-organisation 80’000
hours suggests that ‘if you want to help people in general, your key concern
shouldn’t be to help the present generation, but to ensure that the future goes
well in the long-term’ (Todd 2017). And many Eﬀective Altruists already do-
nate their money towards x-risk reduction rather than, say, short term animal
welfare improvements.
In this paper, I’ll ask how the importance of x-risk reduction should be as-
sessed on a Christian moral theory. My main claim will be that Christian moral-
ity largely agrees with EA that x-risk reduction is extremely important—albeit
for diﬀerent reasons. So Christians should emphatically support the abovemen-
tioned measures to increase the probability of Survival.
Let me clarify. First, there’s no such thing as theChristian moral doctrine.
One of the philosophically most elaborate and historically most inﬂuential de-
velopments of Christian thought is the work of Aquinas. So I’ll take this as my
starting point, and argue ﬁrst and foremost that core Thomist assumptions sup-
port x-risk reduction. Thomas’s speciﬁc interpretation of these assumptions are
often unappealing today. But I’ll also claim that they can be interpreted more
plausibly, that their core idea is still authoritative for many Christians, and that
on any plausible interpretation they ground an argument for x-risk reduction.
So while I’ll start with Thomas, my conclusions should appeal to quite many
contemporary Christians. Indeed, I’ll ultimately indicate that these assump-
tions needn’t even be interpreted in a speciﬁcally Christian manner, but emerge
2
in some form or other from a number of worldviews (cf. section 4). Second,
there are diﬀerent x-risk scenarios, and they raise diﬀerent moral issues. I think
the case is clearest for ways in which humanity might literally go extinct, before
being superseded by non-human intelligence, and as a direct consequence of our
own actions. I’ll refer to these cases as as ‘non-transitionary anthropogenic ex-
tinction’, andit’sonthesecasesthatI’llfocus. Itwouldbeinterestingtoexplore
other scenarios: cases in which we’re replaced by another form of intelligence,
non-extinction ‘x-risks’ (which Bostrom’s deﬁnition includes) like an extended
stage of suﬀering, or scenarios of natural extinction like volcano eruptions. My
arguments will have upshots for such cases too. But I won’t explore them here.
Third, there are diﬀerent ways in which, or diﬀerent agents for whom, x-risk
reduction might be ‘important’. In what follows, I’ll mostly be considering a
collective perspective. That is, I’ll assume that we as humanity collectively do
certain things. And I’ll focus on whether weought to do anything to mitigate
x-risks—rather than on whether you individually ought to. The existence of this
collective perspective might be controversial. But I think it’s plausible (see e.g.
Dietz 2019). Christian moral theory, or at least Thomas, also seems to assume
it (cf. section 2.1). And many important issues emerge only or more clearly
from it. So I’ll assume it in what follows.
In short, my question is about how important it is, on roughly Thomist
premises, for us to reduce risks of non-transitionary anthropogenic extinction.
I’ll ﬁrst present three considerations to the eﬀect that, if we diddrive ourselves
extinct, thiswouldbemorallyveryproblematic—ahubristicfailureinperfection
with cosmologically bad eﬀects (section 2). I’ll then discuss some countervailing
considerations, suggesting that even though such extinction would be bad, we
needn’t take measures against it—because God won’t let it happen, or because
we wouldn’t intendit, or because at any rate it isn’t imminent (section 3). I’ll
argue that none of these latter considerations cut any ice. So I’ll conclude that
on roughly Thomist premises it’s extremely important for us to reduce x-risks.
2 Three Thomist Considerations
There are many Thomist considerations that would bear on x-risks. For in-
stance, in driving ourselves extinct, we’d presumably kill the last representatives
of humanity. On a Thomist perspective, those killings will be morally problem-
atic simply as killings (see ST, ii-II, q64). Yet this has nothing to do with the
fact that those killings lead to extinction. So let’s see whether there would be
anything distinctly problematic about extinction, if we brought it about. There
is.
2.1 The natural law
A ﬁrst consideration follows from Thomas’s teleology, or from the Aristotelian
strand in his thinking. Recall that for Thomas the order of the cosmos is
teleological. This teleology is grounded in the fact that the cosmos is subject
to God. And it takes the form of a law for us: ‘the universe is governed by
Divine Reason. Wherefore the very Idea of the government of things in God
[...] has the nature of a law.’ (ST, i-II, q91 a1, co) For Thomas, following this
‘eternal law’—or Divine ‘will’ (ST, i-II, q93 a4, ad1) or ‘plan’ (ST, i-II, q93 a3,
3
co) for all things—is theethical imperative for us. So what does it command?
We can’t know God’s intent ‘in itself’ (ST, i-II, q93 a2, co), at least not in this
earthly life (see ST, i-II, q93 a2, co; ST, I, q12 a11). But we can know it ‘in
its eﬀect’, through its manifestations in creation, or through the ‘natural law’
that we recognise as structuring the physical universe. In particular, we can
detect God’s plan for us through the natural inclinations He’s implanted in us:
‘all things partake somewhat of the eternal law[:] [...] from its being imprinted
on them, they derive their respective inclinations to their proper acts and ends’
(ST,i-II,q91a2, co). Inotherwords, ourinclinationsallowanindirectcognition
of the essence of God’s will, quite like sunrays allow an indirect cognition of the
substance of the sun (ST, i-II, q93 a2, co). So what are our natural inclinations?
Thomas speaks of three kinds: ‘in man there is ﬁrst of all an inclination [...]
which he has in common with all substances: [...] the preservation of its own
being [...]. Secondly, there is in man an inclination [...] which he has in common
with other animals: [...] sexual intercourse, education of oﬀspring and so forth.
Thirdly, there is in man an inclination to good, according to the nature of his
reason [...]: [...] to know the truth about God’ (ST, i-II, q94 a2, co). What’s
crucial for present purposes is the second type of inclination. Procreation or
the ‘preservation of the species’ is ﬁrmly part of our ‘natural good’ (SCG, III,
122-9), or of what the natural law commands us to do.
Now Thomas doesn’t believe that everyone must follow all of these inclina-
tions, or that everyone must have oﬀspring. It’s permissible for some to remain
celibate (see e.g. ST ii-II, q152). But we as a collective have a duty—a ‘duty [...]
to be fulﬁlled by the multitude’ (ST ii-II, q152 a2, ad1)—to procreate. So this
grounds a straightforward consideration for x-risk reduction. By going extinct,
we’d fail to attain our end, or to accord with the natural law. Indeed, our failure
would be profound. It wouldn’t just be some of us ﬂouting this law—the bad
apples in an overall virtuous whole. We’d fail collectively , as an entire species,
to attain our end. And (at least as far as this life’s concerned) we wouldn’t just
fail in one aspect of perfection, while still able to excel in others. Our survival is
a precondition for any aspect of our ﬂourishing. So our extinction would mean
we failcomprehensively , in all respects of our end. And of course we wouldn’t
just temporarily fall short of our calling. Once we’ve gone extinct, there’s no
second bite at the apple. It would mean we’ve foundered irreversibly . So the
moral failure in anthropogenic extinction would seem complete . In short:
Natural law: We ought to attain our natural end. Our extinction
would prevent us from doing so—collectively, comprehensively, and
irreversibly. Thus non-transitionary anthropogenic extinction would
amount to a total moral failure of us as a species.
That’s a ﬁrst consideration for why our extinction would be problematic.
Now I suppose that this kind of rationale isn’t parochially Thomist, but
should appeal to Christians quite broadly. Thomas himself interprets the nat-
ural law pertaining to procreation very radically—e.g. as permitting a non-
procreative life only for the sake of the ‘contemplation of truth’ (ST ii-II, q152
a2, co; also ST ii-II, q153 a2, co),2and as prohibiting any intercourse known to
2Thomas doesn’t say this explicitly in these passages. He says that the goods of the body
are subordinate or ‘directed’ to the goods of the soul, and that virginity (or a lack of bodily
good) is justiﬁed if done for the sake of Divine contemplation (or good of the soul; ST ii-II,
q152 a2, co). I’m reading the conditional here as a biconditional.
4
be non-reproductive (SCG, III, 122; also ST ii-II, q153 a2, co). This would mean
that our procreation-related obligations go much beyond preventing extinction.
And it would mean that contemporary liberal moral thought is radically wrong
about the good human life, and about intercourse among people of the same
sex, or people who for whatever reasons cannot or don’t want to reproduce.
Many contemporary Christians will want to resist these implications. But we
needn’t understand the general idea of a ‘natural law’ in this manner. Plau-
sibly, other aspects of the human end (athletic, social, emotional) are just as
integral as ‘the contemplation of truth’. So there are good lives without chil-
dren beyond those of philosophers and priests (see e.g. Nussbaum 1987 or 2011).
Also, perhaps there are other functions of human sexuality (e.g. bonding), such
that non-reproductive intercourse isn’t a misuse of sexual organs. After all,
there’s plenty of non-reproductive sexuality among non-human animals (see e.g.
Bagemihl 1999). The details of the natural law are a matter of large debate.3
But I presume that the generalidea of a ‘natural law’ is still quite prominent
for Christians today. Indeed, assuming the universe manifests God’s intentions,
it’s a very natural assumption. And I suppose that on any plausible interpre-
tation, it will ground a consideration against extinction: whatever it implies
about childfree individuals, contraception or homosexuality, it seems hard to
square the natural law with an heirless self-eradication of our species. If the law
commands anything, it seems, it commands us to ‘be fruitful and multiply’ (Gen
1:28). So a consideration along these lines should be authoritative to Christians
quite broadly. Self-inﬂicted extinction would constitute a total failure in our
executing our designated role.4
2.2 Humility
However, there’s more to anthropogenic extinction than a failure to reproduce.
Let’s look at the precise way in which, through anthropogenic extinction, we’d
fail to attain our end. According to Thomas, there are diﬀerent ways to fall
short of perfection. One is through utter passivity, or sloth, or a ‘sorrow’ that
‘so oppresses man as to draw him away entirely from good deeds’ (ST, ii-II,
q35 a2, co). So we might just not bother to do anything much at all, and
therefore fail in perfection. Another way of failing lies in falling too low, or
being overcome with ‘the lower appetite, namely the concupiscible’ (ST, ii-II,
q153 a5, co). So we might behave like lower animals, and fail to live upto our
standards. But drawing on Augustine, Thomas says that ‘the most grievous of
sins’ (ST, ii-II, q162 a6, co) consists in aiming too high—in failing to respect
our limitations, or acting as if we were God. To do so is to commit the sin
of pride, hubris, or superbia. Following the church father (De Civ. Dei XIV,
13), Thomas characterises a prideful man as someone who ‘aims higher than
he is’, or does not ‘tend to that which is proportionate to him’ (ST, ii-II, q162
a1, co). And what’s proportionate to us is of course not so by coincidence,
but due to Divine assignment. So pride is opposed speciﬁcally to humility:
3For a classic systematic exploration of natural law, see Finnis (2011). For an in-depth
treatment of Aquinas’s theory, see e.g.—among very many others—Lisska (1998).
4Historically, this broad rationale hasn’t appealed to all Christians, of course. Paul himself
seems to suggest it would be best if everyone was celibate (see 1 Cor 7:7). And the Cathars
even thought reproduction was a moral evil. I thank Felix Timmermann and Christoph Halbig
for pointing this out to me.
5
‘humility properly regards the subjection of man to God [...]. Hence pride
properly regards lack of this subjection, in so far as a man raises himself above
that which is appointed to him according to the Divine rule’ (ST, ii-II, q162 a5,
co). And in this sense, as far as the ‘aversion from the immutable good’ (ST,
ii-II, q162 a6, co) is concerned, pride is the most grievous sin: it’s not just a
failure through ignorance or weakness or an innocent desire for another good,
but an active ‘withstanding’ or ‘resisting’ or manifesting ‘contempt of’ God (ST,
ii-II, q162 a6, co).
What does this imply in practice? Thomas speciﬁes what he means. Pride
isn’t any old undue desire. It’s, speciﬁcally, an ‘appetite for excellence in excess
of right reason’—or an inordinate imitation of the powers or competences of
God (ST, ii-II, q162 a1, ad2; emphasis added). This may take various forms.
We may be pridefully curious about things we can’t know, such as facts about
good and evil (ST, ii-II, q163 a1, ad3). Or we may unduly discard our need for
Divine grace, deeming ourselves capable of happiness on our own (ST, ii-II, q163
a2, co). But a more speciﬁc power that isn’t appointed to us is decisions about
life and death: ‘it belongs to God alone to pronounce sentence of death and
life’ (ST, ii-II, q64 a5, co). Thus to kill someone, or (I take it) actively prevent
them from coming into existence, is generally to show an appetite for a power
that doesn’t pertain to us. And if all of this is true, then non-transitionary
anthropogenic extinction in particular would manifest an enormous form of
pride. Note that on most such scenarios, we’d fall prey to technologies we
were unable to control—nuclear weapons, artiﬁcial intelligence, biotechnology,
orwhatever. Soourextinctionwouldmeanthatwe’doverestimatedourmastery
over these fabrications, and the invulnerability we could leverage in the face of
them. It would mean we were prideful in the general sense of desiring an undue
excellence. And the upshot of this would be, speciﬁcally, a life-death decision
on an astronomical scale: preventing lives perhaps by the million billions. It
would mean we were prideful in this more speciﬁc sense too. Or in short:
Humility: Non-transitionary anthropogenic extinction would mean
we overstrained our power as a species. And the upshot of it would
be a life-death decision on an astronomical scale. Thus it would
amount to an enormous form of superbia.
That’s a second consideration for why our extinction would be problematic.
And here too, I suppose this consideration should appeal to Christians
quite broadly. Again, Thomas’s speciﬁc interpretation of God’s authority over
life/death-decisions should be controversial. He suggests that, while permitting
us to execute death penalty (ST, ii-II, q64 a2, co), this authority absolutely pro-
hibits suicide (ST, ii-II, q64 a5, co), and prohibits abortion from the moment of
ensoulment (see e.g. ST, I, q118f.)—which some people have claimed, according
to Thomas’s metaphysical principles and the known facts about embryology,
takes place at the moment of fertilisation (Haldane and Lee 2003, 273).5This
would mean self-extinction can under no circumstances be permissible. And it
would mean that contemporary liberal moral thought is radically wrong about
death penalty, abortion, or suicide and euthanasia. Many contemporary Chris-
tians will want to resist these implications. But again we needn’t interpret the
5In the Scriptum super Sententiis , following Aristotle, Thomas himself suggests that the
soul is infused after 40 days for males and after 90 days for females (SSS III, d3 q5 a2, co).
6
general idea of superbia in this manner. After all, it’s implausible that crim-
inals are ‘dangerous and infectious to the community’ and must be cut away
like an infected part of a body (ST, ii-II, q64 a2, co). Perhaps suicide can in
some instances of extreme pain, or loss of autonomy or dignity, be a manifes-
tation of self-love. And if so, perhaps we can then view ourselves as authorised
by God—or His commandment to love ourselves (e.g. Mat 22:39)—to end our
lives. After all, Thomas himself (defending Abraham’s intention to kill Isaac)
suggests that ‘he who at God’s command kills an innocent man does not sin’
(ST, ii-II, q64 a6, ad1). Perhaps some forms of abortion (e.g. after rape) can
also be seen as an expression of self-love or -respect. Or perhaps we must as-
cribe to Aquinas a diﬀerent view of ensoulment (Pasnau 2002), or simply reject
some of his metaphysics in light of more recent discoveries. Again, the details
ofsuperbia are contested.6But I assume that the pertinent general idea is still
prominent among Christians today. Indeed, that playing God is a sin is a natu-
ral corollary of theism. The in-principle-ban on life/death-decisions has a very
ﬁrm grounding in the Bible (Thomas cites Deut 32:39, for instance). And I sup-
pose that on any plausible interpretation, these ideas ground a consideration
against extinction: whatever they imply about death penalty, abortion, and
suicide, the dictates of humility seem hardly compatible with our developing a
technology that accidentally seals the fate of our whole species. So again, such
a consideration should have import for Christians quite broadly. Self-inﬂicted
extinction would constitute a shattering form of superbia.
2.3 The value of humanity
But we need to see another aspect of Thomas’s view of humanity too, which
is perhaps most distinctly Biblical, and which is implicit in the third kind of
inclinationheascribesus. Forsure, we’renotGod. Butwearenonethelessmade
to know the truth about Him. In fact, of all corporeal things (i.e., disregarding
angels) we’re the only ones whose nature enables such knowledge. And this, for
Thomas, marks our ‘dignity’. It’s this dignity which made it ﬁtting for Jesus
to adopt humannature, rather than becoming an animal or any other thing:
‘in the irrational creature the ﬁtness of dignity is wanting.’ (ST, III, q4 a1,
co) Indeed, it’s these intellectual capacities that ground our likeness to God—
a likeness greater than that of any non-reasoned creature (see ST, I, q93 a2,
co), and suﬃcient to say we’re His ‘image’: ‘intellectual creatures alone [...]
are made to God’s image.’ (ST, I, q93 a2, co) And it’s this which ultimately
manifests that God loves us more than any other thing. So Aquinas quotes
Augustine approvingly: “‘God loves all things that He has made, and amongst
them rational creatures more, and of these especially those who are members of
His only-begotten Son Himself.”’ (ST, I, q20 a3, sc)
In other words, and as Thomas says very explicitly (ST, I, q20 a4, co), of all
6There’s a lot of recent literature concerning Thomas on humility. For longer treatments,
see e.g. Tadie (2006) or Fullam (2001). As far as I see, Thomas himself doesn’t discuss whether
birth control or contraception infringes on God’s dominion over life/death-decisions. But the
Catholicchurchhassinceleveragedthisargument. Yetperhapsabanoncontraceptionneedn’t
follow from humility either. Perhaps Thomists may appeal to the doctrine of double eﬀect,
and compare well-intentioned prevention of fertilisation with well-intentioned killing in self-
defense (cf. section 3.2). Or perhaps they might again claim to be authorised in this decision
by the commandment to love ourselves, and love our partners, and our (potential) children
for whom we couldn’t be suﬃciently responsible parents.
7
corporeal things we are the most valuable, or those with most ‘goodness’. And
this diﬀerence is categorical. So our extinction would have cosmological rami-
ﬁcations. For standard utilitarians, there’s no categorical diﬀerence between a
world populated by ﬂourishing societies of people and a world populated by one
lonely lizard basking in the sun and feeling a tinge of pleasure. The diﬀerence
is a matter of degree. For Aquinas that’s diﬀerent. In a world devoid of higher
intelligence, there’s nothing that’s made to God’s image—nothing with our spe-
cial dignity or perfection. This would radically undercut the perfection of the
universe, as God created it, which depends on the varieties of goodness (see e.g.
ST, I, q47). So our extinction would change the face of creation. Or in short:
The value of humanity: Non-transitionary anthropogenic extinc-
tion would constitute the destruction of the most valuable aspect of
creation—and thus a loss of categorical cosmological signiﬁcance.
That’s a third consideration for why our extinction would be problematic.
Again, I suppose that this consideration should appeal to Christians very
broadly. Thomasinterpretstheorderofcreationveryradically. Hesuggeststhat
everythingelseexists for us(ST,ii-II,q64a1,co)—suchthatwemayuseanimals
simply as means for our ends, say, and the self-interested killing of another
person’s ox wrongs at most its owner (ST, ii-II, q64 a1, co). This would mean
that our extinction would literally destroy the purpose of the physical universe.
And it would mean that much contemporary thought is radically wrong about
animals, or other aspects of the natural world. Again, many Christians will
want to resist these implications, or so I hope. But the distinct value of humans
needn’t be interpreted this radically. Perhaps our ‘dominion’ over animals (Gen
1:26) doesn’t mean we can use them simply as means. Perhaps it means we
must use our de factopower in the manner of a loving and respectful and liberal
guard (see e.g. Linzey 2016, ch. 2). And similarly with every other aspect of
creation—ecosystems, plants, and the climate. Again, the exact nature of our
status is a large question. But the general idea of our special value still seems
very prominent. It does seem hard to avoid if we take seriously that man is
‘God’s image’, or has a special (perhaps responsibility-implying) dominion over
the earth—and very plausible given God’s human embodiment in Christ. And
on any interpretation, our special status will ground a consideration against
extinction: whatever it implies about our responsibilities towards animals, the
faceofcreationwillbechangedcategoricallyifwedriveourselvesextinct. Sothis
consideration should be authoritative to Christians very broadly. Self-inﬂicted
extinction would constitute a destruction with cosmological import.
Plausibly, there are other Christian considerations that bear on x-risks, at
least once we move beyond Thomas. Most notably, perhaps Christian caritas
simply gives us reasons to increase expected impartial welfare (see e.g. William
Paley’s utilitarian Christianity, in his Principles of Moral and Political Philoso-
phy; Paley 2014, esp. book II). If it does, the EA rationale will be very pertinent
to Christians as it stands. But whether that’s an apt interpretation of the Chris-
tian virtue—or whether, as I personally ﬁnd more likely, the latter is more about
making people happy than about making happy people—will be controversial.
And at any rate, I think these are the three most distinctly Christian concerns.
So let me leave it at that for now.
8
3 Discussion
If all of this is right, non-transitionary anthropogenic extinction would be a
morally highly problematic result. Such extinction wouldn’t just amount to a
regrettable form of imprudence—but to a failure to fulﬁll our God-given role.
It wouldn’t amount to any old failure of this kind—but to a prideful miss of our
end. And it wouldn’t be just an inconsequential overstepping of our dominion—
but an unauthorised decision with categorical cosmological ramiﬁcations.7But
as mentioned, humanity can now (in the form of the present generation) take
measures to reduce the likelihood that it will eventually eﬀect this result. So
this suggests that we have very strong reasons to take some such measures.
It suggests that Christians too have strong reasons to donate their money to-
wardsx-riskreductionratherthan, say, disasterrelief; toconductx-riskresearch
rather than enquiries about the cause of the grief of a neighbour; or to advocate
political measures for long-term safety rather than for short-term caritative pur-
poses. But let’s not get ahead of ourselves. Some considerations in Thomas’s
philosophy seem to suggest that even if extinction would, as far as we know, be
bad, it’s not important that we now do much about it in practice. So let me
turn to some of these theological and moral countervailing concerns. This will
not simply corroborate the results so far. It will also help clarify the precise
form and weight of what the above rationale implies.
3.1 Theological considerations: Divine providence
One apparent reason against x-risk activism is Divine providence. Again, for
Thomas, everything is subject to God. And Thomas’s God is all-knowing, all-
powerful, and all-good: ‘In God there exists the most perfect knowledge’ (ST,
I, q14 a1, co), ‘He can do all things that are possible absolutely [or don’t imply
a contradiction in terms]’ (ST, I, q25 a3, co); and He ‘loves all existing things’
(ST, I, q20 a2, co). One might conclude from this that God won’t allow us to go
extinct, or that if He does it’s somehow just for the better. And from this one
might infer that we needn’t do anything to prevent our extinction in practice.
X-risk reduction is obviated by the rule of a loving God.
Now this is diﬃcult and well-trodden terrain. But God’s existence doesn’t in
generalseem to warrant any heedlessness. Consider risks of road accidents, say.
And suppose any accident accords with His will. It’s an interesting question
what precisely this implies. Perhaps it warrants a certain ultimate serenity or
comfort: a reassurance at the thought that whatever happens on our roads has
its mysterious rightness in the grander scheme of things. Perhaps it warrants
a fundamental form of trust: a consolation in the belief that our diligence will
be duly rewarded (see ST, ii-II, q22 a1, co). But God’s unfathomable values
cannot act as a guide for us, or as an excuse to depart from the norms and
expectationswe’regiven. SotheseformsofChristianhopemustbedistinguished
from optimism that accidents won’t occur, or from feeling exonerated from the
need to take caution. Christians ought to see to it that they stop at red lights,
respect speed limits, and check their brakes—and just as carefully as everyone
else. Indeed, Thomas is the ﬁrst to emphasise that we’re obligated to such
7Perhaps it’s worth noting that in principle, these considerations are logically independent.
One might accept some but not all of them. For instance, one might doubt that our natural
inclinations reveal a Divine law, but still accept the cosmological disvalue of human extinction.
9
circumspection (see e.g. ST, ii-II, q64 a8, co). In short, Divine providence
doesn’t aﬀect our need to reduce road risks in practice. But then it’s unclear
why it should do so with risks of human extinction.8
One might suggest that there’s something special about human extinction,
setting it apart from everyday hazards, and making it particularly unlikely.
Perhaps it’s precisely because we’re His ‘image’, or uniquely most valuable,
that God won’t allow us to perish. Perhaps Jesus’s redemption of mankind
would have been futile if some sorrowful two thousand years later He let us
burn up or wither away.9Or perhaps, more speciﬁcally, there’s evidence in
scripture that we’ll survive: the primal great ﬂood precisely didn’terase us,
and after that deluge there seems to have been a promise of survival—that
‘never again will all life be destroyed by the waters of a ﬂood.’ (Gen 9:11)
This isn’t the place to dive deep into Christian theology. But it’s hard to
see why such reasonings should give us much conﬁdence. The Lord moves in
mysterious ways. If all known misery is compatible with His providence, it
must surely at least be possible that He’d allow us go extinct. In particular,
there are many more passages in scripture painting a grim prospect of extinction
than promising a boundless glorious future. And many such visions of the ‘end
of time’ indicate anthropogenic extermination—that ‘the nations in the four
cornersoftheearth’aregatheredfor‘battle’or‘war’(Rev20:8),rightbefore‘the
earth andthe heavens’ are gone(Rev 20:11). Ifanything, accordingto the Bible,
anthropogenic extinction seems a very live option. So Divine providence might
have implications for the metaphysics and ultimate unfathomable signiﬁcance
of our doomsday. But it doesn’t seem to warrant ourheedlessness about x-risks
in practice. If the above considerations are sound, we, just as any generation in
the future, must see to it that it isn’t uswho bring a Johannine ﬁnale about.
3.2 Moral considerations: deontology
Let’s look at moral considerations that might mitigate the importance of x-
risk reduction. One such consideration concerns intentions. For Thomas, the
permissibility of our actions can depend on what we intend. More precisely, he
held, or indeed introduced, the doctrine of double eﬀect (or ‘DDE’). According
to this doctrine, there’s a diﬀerence between the eﬀects we intend an action to
have, and the eﬀects we merely foresee but don’t speciﬁcally intend. While it’s
alwaysimpermissibletointendevileﬀects, itcanbepermissibletocausethem, if
what you intend is good. For instance, you may kill in self-defence, if you intend
to save your life and merely foresee the death of your aggressor (see ST, ii-II,
q64 a7, co). This bears on x-risks. Perhaps non-transitionary anthropogenic
extinction would be a very bad result. But one might suggest that as long as we
don’tintendtoeﬀectit, wewouldn’thaveactedimpermissibly: anunintentional
8In his contribution to this collection, Dominic Roser suggests that Christianity warrants a
certain renunciation of control. I’m not sure whether he intends this to contradict my claims
here—and to imply, say, that Christians may reasonably check their brakes half as often as
atheists. If so, his view seems to me, among other things, unstable. It seems that God’s
existence would either require standard full-blown caution (as I think Thomas suggests), or
would warrant totalrelinquishment of it. It seems hard to see why He would warrant a certain
butonlya certain trust in the course of events. At any rate, I’d think most Christians don’t
understand their faith in this manner. And even if Roser is right, any such limitedtrust in
things would arguably still not undermine my practical conclusions.
9I thank Felix Koch for mentioning this thought to me.
10
mass life-prevention isn’t prideful, and an unintentional thwarting of perfection
or erasing of God’s image isn’t morally wrong. So if our intentions are ﬁne, we
needn’t worry about x-risk reduction.10
But this argument is a non-starter. It might well be worse to intend our ex-
tinction rather than to merely foresee it. For Thomas, it would mean that our
action would lack ‘goodness from its end’, and not just from its circumstances
or species (ST, i-II, q18, esp. a7, co). But this doesn’t mean that unintentional
extinction wouldn’t be wrong, or even speciﬁcally prideful. There’s no blanket
permission for the well-intentioned. You mustn’t speed through the cross-walk
and put people at risk, even with the laudable aim of being punctual at the fac-
ulty meeting. Thomas says explicitly that you are ‘in a sense guilty of voluntary
homicide’—and thus (I take it) of superbia—if you kill someone unintentionally
but without having taken ‘due care’ (ST, ii-II, q64 a8, co). He doesn’t specify
when precisely the DDE allows you to accept a foreseen evil. But he suggests
it depends on ( i) the expected goodness of the intended good, ( ii) the expected
badness of the foreseen evil—or on the ‘proportion’ between the two (ST, ii-II,
q64 a7, co)—and ( iii) on whether the harmful action is ‘necessary’ (ST, ii-II,
q64 a7, co) for the good, or whether there are ways of securing the good with-
out these bad eﬀects. These criteria decidedly command x-risk reduction. Sure,
many technologies that involve such risks also promise important goods. But if
my arguments are right, the moral costs are potentially tremendous. And there
are less risky courses of action which detract little from the expected good. The
above-mentioned measures would reduce x-risks, but wouldn’t really jeopardise
the beneﬁts these technologies promise. So it seems absolutely obligatory to
take them. Going on as we do does seem like scorching through the cross-walk
for timeliness at the meeting. That isn’t killing for the sake of the killing. But
it’s a serious violation of the negative constraint of the DDE. And thus it’s
surely grave enough.11
Let’sconsideranothercountervailingconsideration. Perhapsextinctionwould
be terrible. But for all we know, it isn’t actually imminent. Indeed, compared
to more immediate moral callings like global poverty, gender justice, or dis-
aster relief, it seems very remote. According to utilitarianism or EA, such
distance doesn’t matter. These views are absolutely impartial. But perhaps
Christian morality is diﬀerent. One might suggest Christian morality is more
concerned with visible, immediate, near-at-hand moral problems—the wounded
person alongside the road (Luke 10:30), or perhaps the literal ‘neighbor’ (Mark
12:31)—and doesn’t warrant too much concern about such far-distant matters.
In fact, Thomas himself is explicit that we should be partial, at least in the
virtue of caritas: ‘Among our neighbors, we should love them more who are
10I thank Eric Sampson and Jonathan Erhardt for mentioning this thought to me.
11Strictlyspeaking, perhapsextinctionwouldn’tevenbea‘foreseen’eﬀectofouractions. By
‘foreseen’ [ praecogitatus ] Thomas seems to mean ‘known with certainty to result’ (see e.g. ST,
i-II, q20 a5, co). But we aren’t certain that promoting AI, say, will result in extinction. We’re
just not certain that it won’t. In discussing the DDE, Thomas doesn’t deal with uncertainty.
But he does elsewhere. In ST, i-II, q20 a5, co, he says: ‘if the consequences [of an action] are
not foreseen, we must make a distinction. Because if they follow from the nature of the action
and in the majority of cases [...] the consequences increase the goodness or malice of that
action [...]. On the other hand, if the consequences follow by accident and seldom, then they
do not increase the goodness or malice of the action.’ This can’t be right. Throwing stones
oﬀ a cliﬀ might kill passersby below in only 5% of cases. But then it’s nonetheless wrong.
Thomas lacked the concept of expected value. Today, we’d surely interpret the doctrine in
terms of that concept, or some related one.
11
more closely connected to us’ (DQV, q2 a9, co; cf. ST ii-II, q31 a3, co). So one
might conclude that although our extinction would be bad, we needn’t worry
about x-risk reduction—or at least not now, or not with resources we could
direct towards these more immediate concerns.
But this would be a mistake. Christian morality may be partialist about
caritas. So there may be a tension between Christian benevolence and the
impartialist EA-directive to ‘do the most good’. But on the considerations
I’ve sketched, reducing x-risks isn’t a form of ‘doing good’, or of charity, or
of fulﬁlling any positive obligation. It’s to ensure—or make more likely—that
we don’t ﬂout our end, overstep our dominion, or wreck the crown of creation.
Formally, it’s to ensure we satisfy the constraint of the DDE. In other words,
it’s to respect a perfect negative duty. And Thomas doesn’t seem to endorse
partiality or discounting in such negative duties, and neither does Christian
morality more broadly. On Christian morality, killing, say, is wrong. And doing
what will kill someone in a month is presumably ceteris paribus just as wrong as
doing what will kill someone in a year, or in a thousand years for that matter.
So the sheer temporal distance of human extinction in itself doesn’t seem to
obviate x-risk reduction. On the contrary, note that the negative character of
this obligation has implications for how it may be weighed against others. For
utilitarians, the obligation to reduce x-risk is formally on a par with (other)
obligations of benevolence, such as obligations to support the poor. So it ought
to be weighed against them. For Christians, if I’m right, this is diﬀerent. As a
negative obligation, the obligation to reduce x-risks must not be weighed against
positive imperfect obligations, or can’t be discharged by doing enough by way
of benevolence elsewhere. It’s quite simply a perfect duty.
There’s a ﬁnal point worth noting. For utilitarians, notoriously, we may take
any means for the sake of the good end. If killing an innocent scientist reduces
x-risks, we presumably ought to kill them. For Thomist Christians this will be
diﬀerent. Thomas explicitly accepts deontological constraints: ‘some [actions]
are evil, whatever their result may be.’ (ST ii-II, q88 a2, ad2) So Thomist
Christians must not do anything to reduce such risks. They generally mustn’t
kill or lie or steal for that purpose. In practice, however, this won’t make much
of a diﬀerence. The most salient means of x-risk reduction include academic
research, or global measures for peace, sustainability or AI safety. None of
these measures seem to violate any constraints. So even if Christian morality
is deontological in nature, there’s plenty of good ways to start making Survival
more likely.
4 Conclusion
Ifallofthisisright, it’snotjustthatnon-transitionaryanthropogenicextinction
would, as far as we know, be a disastrous result—a cosomologically salient
prideful miss of our end. At least in practice, and as a matter of a negative
constraint against lack of ‘due care’ that in principle seems neither discountable
nor weighable against positive obligations, Thomist Christians have very strong
reasons to take deontologically permissible means to prevent such extinction:
to conduct research on risks and risk-reduction, promote political arrangements
with an eye to the very far future, donate heir money towards x-risk mitigation,
and so on. Indeed, given the gravity of the possible eﬀect, and the perfect or
12
negative form of the duty, they seem to have reason to do this even if it will
considerably constrain their resources for classical forms of caritas.
Or that’s as far as our argument takes us. There are many considerations
relevant to non-transitionary anthropogenic extinction that I haven’t yet ad-
dressed. For instance, it would be interesting to explore the implications of
Christian love for our question; to consider the relevance of other Christian
virtues—such as temperance, diligence, or patience; or to integrate the assump-
tion that in some form or other we’ll always live on, or that in this sense we
can’t really die out.12That’s beyond the scope of this paper. It would also
be interesting to consider the implications of my arguments for issues beyond
my core question. Take risks of natural extinction. If we ought to ensure the
preservation of the species, we must generally guard ourselves also against as-
teroid hits. It would presumably be a form of superbia to presume that no such
event could erase us. And to let it happen would mean to let creation’s most
valuable part be destroyed. Allowing natural extinction might not be as grave
as actively extinguishing ourselves, but still seems a large-scale moral failure.
Another, and more intricate question, concerns the issue of non-human higher
intelligence. Suppose we turned into a nun-human AI and left mankind behind.
Would we then miss our end (in the non-preservation of the species), or would
we precisely fulﬁll it (in the perfection of our ingenuity)? Would it be a form of
superbia to thus intervene in the nature of species, or would that belong to our
natural proportionate capacities? And would the most valuable aspect of the
universe be lost, or would the cosmos become more valuable if inhabited by a
more perfect form of reason?13Again, these are questions for another occasion.
There’s also the question whether similar arguments emerge on other reli-
gious or non-religious worldviews. They arguably do. The normative core of the
ﬁrst two arguments is simply a kind of perfectionism; and the core of the third
argument is the idea of a special value of humanity. In Christianity these as-
sumptions are grounded in the existence of the Christian God. But they needn’t
be. Insomeformorother, youcanadoptthemwithoutbelievinginthatGod, or
indeed in any form of theism. We might see them as emerging, at bottom, from
very general aspects of the Christian view of ourselves: from the ambivalent
sense that there’s something greater than us, but that we nonetheless are quite
great indeed. Perfectionism expresses the idea that what structures the universe
exceeds mankind and is somehow commanding for us—so that we ought to fulﬁll
our role in the scheme of things, and accept the limitations of it. The idea of our
special value expresses that we have a certain greatness nonetheless—that our
role isn’t any old role, and that it would matterif we were gone. It’s at bottom
this dichotomous nature, fallen and fragile yet valuable, which implies we should
be exceedingly careful with ourselves. Christians, and everyone with a similar
view of mankind, and of our obligations and limitations and value, should agree
with Eﬀective Altruists that x-risk reduction is extremely important.
Acknowledgments. For helpful comments on earlier versions of this paper, I thank the par-
ticipants of the workshop ‘Religious Perspectives on Eﬀective Altruism’, the participants of
the 5th Oxford Workshop on Global Priorities Research, as well as Christoph Halbig, Samuel
Hughes, Sebastian Muders, Dominic Roser, Philipp Schwind and Felix Timmermann.
12I thank Dominic Roser for mentioning this thought to me.
13I thank Mara-Daria Cojocaru and Carin Ism for mentioning these questions to me. For a
generally positive Christian stance on enhancement, see e.g. Keenan (2014).
13
References
Aquinas, Thomas. 2010. Disputed Questions on Virtue [DQV]. Translated by
Jeﬀrey Hause and Claudia Eisen Murphy. Indianapolis: Hackett.
Aquinas, Thomas. 1920. Summa Theologica [ST], second and revised edition.
Translated by Fathers of the English Dominican Province. London: Burns
Oates & Washbourne.
Aquinas, Thomas. 1955-57. Summa Contra Gentiles [SCG].TranlatedbyAnton
C. Pegis, James F. Anderson, Vernon J. Bourke, Charles J. O’Neil, edited by
Joseph Kenny O.P. New York: Hanover House.
Aquinas, Thomas. Scriptum super Sententiis [SSS]. Accessed September 17,
2019. http://www.corpusthomisticum.org/iopera.html.
Augustine. 2017. The City of God Books XIII and XIV [De Civ. Dei]. Edited
and Translated by Peter G. Walsh. Liverpool: Liverpool University Press.
Bagemihl, Bruce. 1999. Biological Exuberance: Animal Homosexuality and
Natural Diversity . New York: St Martin’s Press.
Bostrom, Nick, and Milan M. and Ćirković, eds. 2008. Global catastrophic risks .
Oxford: Oxford University Press.
Bostrom, Nick. 2003. “Astronomical Waste: The opportunity cost of delayed
technological development.” Utilitas15(3): 308-314.
Bostrom, Nick. 2013. “Existential Risk Prevention as Global Priority.” Global
Policy4 (1): 15-31.
Beckstead, Nick. 2013. “On the overwhelming Importance of Shaping the Far
Future.” PhD diss., Rutgers.
Bucknam, Mark, and Robert Gold. 2008. “Asteroid Threat? The Problem of
Planetary Defence.” Survival 50 (5): 141-156.
Cave, Stephen, and Seán S. ÓhÉigeartaigh. 2019. “Bridging near- and long-
term concerns about AI.” Nature Machine Intelligence 1: 5-6.
Denkenberger, David, and Joshua M. Pearce. 2015. Feeding Everyone No Mat-
ter What: Managing Food Security After Global Catastrophe . London: Else-
vier.
Dietz, Alexander. 2019. “Eﬀective Altruism and Collective Obligations.” Utili-
tas31 (1):106-115.
Finnis, John. 2011. Natural Law and Natural Rights . Oxford: Oxford Univer-
sity Press.
Fullam, Lisa. 2001. The Virtue of Humility: A Reconstruction Based in Thomas
Aquinas. Ph.D. Dissertation, Harvard University.
Haldane, John, and Patrick Lee. 2003. “Aquinas on human ensoulment, abor-
tion and the value of life.” Philosophy 78 (2):255-278.
14
Hanson, Robin. 2008. “Catastrophe, social collapse, and human extinction.” In
Global catastrophic risks , edited by Nick Bostrom and Milan M. and Ćirković,
363-378. Oxford: Oxford University Press.
Keenan, James F. 2014. “Roman Catholic Christianity, Embodiment and Re-
lationality: Roman Catholic Concerns about Transhumanist Proposals.” in:
Transhumanism and the Body: The World Religions Speak , edited by Calvin
Mercer and Derek F. Maher, 155-171. New York: Palgrave.
Linzey, Andrew. 2016. Christianity and the Rights of Animals . Eugene: Wipf
and Stock Publishers.
Lisska, Anthony J. 1998. Aquinas’s Theory of Natural Law: An Analytic Re-
construction . Oxford: Oxford University Press.
MacAskill, William. 2015. Doing good better: how eﬀective altruism can help
you make a diﬀerence . New York: Gotham Books.
Nussbaum, Martha C. 2011. Creating Capabilities: The Human Development
Approach . Cambridge, MA: Belknap /Harvard University Press.
Nussbaum, MarthaC.1987. “Non-RelativeVirtues: AnAristotelianApproach.”
Midwest Studies in Philosophy 13 (1):32-53.
Paley, William. 2014. The Principles of Moral and Political Philosophy . Cam-
bridge: Cambridge University Press.
Pamlin, Dennis, and Stuart Armstrong. 2015. “Global Challenges: 12 Risks
thatthreatenhumancivilisation.” AccessedAugust8,2019. https://api.global
challenges.org/static/wp-content/uploads/12-Risks-with-inﬁnite-impact.pdf.
Parﬁt, Derek. 1984. Reasons and Persons . Oxford: Oxford University Press.
Pasnau, Robert. 2002, Thomas Aquinas and Human Nature . Cambridge: Cam-
bridge University Press.
Pinker, Steven. 2018. Enlightenment Now: The Case for Reason, Science,
Humanism, and Progress . New York: Penguin.
Richter, Daniel, Rainer Grün, Renaud Joannes-Boyau, Teresa E. Steele, Fethi
Amani, Mathieu Rué, Paul Fernandes, Jean-Paul Raynal, Denis Geraads,
Abdelouahed Ben-Ncer, Jean-Jacques Hublin, and Shannon P. McPherron.
2017. “The age of the hominin fossils from Jebel Irhoud, Morocco, and the
origins of the Middle Stone Age.” Nature546: 293-296.
Rushby, Andrew J., Mark W. Claire, Hugh Osborn, and Andrew J. Watson.
2013. “Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars.”
Astrobiology 13 (9): 833-849.
Sandberg, Anders, and Nick Bostrom. 2008. “Global catastrophic risks sur-
vey.”Future of Humanity Institute Technical Report . Accessed May 15, 2019.
http://www.global-catastrophic-risks.com/docs/ 2008-1.pdf.
Tadie, JosephLawrence. 2006. Between humilities: A retrieval of Saint Thomas
Aquinas on the virtue of humility . Ph.D. Dissertation, Boston College.
15
Todd, Benjamin. 2017. “Presenting the long-term value thesis.” Accessed May
15, 2019. https://80000hours.org/articles/future-generations/.
UK Treasury. 2006. “Stern review on the economics of climate change.” Ac-
cessedMay15,2019. https://webarchive.nationalarchives.gov.uk/20100407172811/
http://www.hm-treasury.gov.uk/stern\_review\_report.htm.
United Nations, Department of Economic and Social Aﬀairs, Population Divi-
sion. 2001. “World population monitoring, 2001: population, environment
anddevelopment.” AccessedMay15,2019. https://www.un.org/en/development/
desa/population/publications/pdf/environment/population-monitoring.pdf.
Wiblin, Robert, and Howie Lempel. 2018. “What skills or experience are most
neededwithinprofessionaleﬀectivealtruismin2018? Andwhichproblemsare
most eﬀective to work on? New survey of organisational leaders.” Accessed
May 15, 2019. https://80000hours.org/2018/10/2018-talent-gaps-survey/.
16