Defense in depth (DiD) (sometimes spelled defense-in-depth or defense in-depth) is the use of multiple defense layers to protect against an external threat. The concept was originally developed in the context of military strategy, but has since been applied to many other domains.[1]
Defense in depth against human extinction
A paper by Owen Cotton-Barratt, Max Daniel and Anders Sandberg proposes a defense in depth approach for handling risks of human extinction.[2] Such risks may be analyzed as involving three successive stages in the unfolding of a terminal event: the origination of the catastrophe, its attainment of global scale, and the destruction of everyone alive. To each of these three threats (origin, scaling and endgame) corresponds a particular type of defense layer: prevention, response and resilience. Besides serving to clarify the nature of the risks involved, this analysis can assist efforts to prioritize the allocation of resources among the different defense layers. In particular, if the threats that the layers protect against interact multiplicatively with one another, the impact on overall risk reduction of strengthening a particular layer will depend on the relative size of the change to the probability that the associated threat will get past it: halving the risk posed by a threat reduces total risk by the same degree regardless of the absolute magnitude of the change.
Further reading
Cotton-Barratt, Owen, Max Daniel & Anders Sandberg (2020) Defence in depth against human extinction: Prevention, response, resilience, and why they all matter, Global Policy, vol. 11, pp. 271–282.
Related entries
estimation of existential risk | existential risk | existential risk factor | existential security | global catastrophic risk | unknown existential risk | unprecedented risks
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Muehlhauser, Luke (2021) A personal take on longtermist AI governance, Effective Altruism Forum, July 21, fn. 19.
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Cotton-Barratt, Owen, Max Daniel & Anders Sandberg (2020) Defence in depth against human extinction: Prevention, response, resilience, and why they all matter, Global Policy, vol. 11, pp. 271–282.
Wishlist for a heroic editor to someday tick off:
Add an explanation of the basic concept
Add a mention or explanation of the many similar/identical concepts that go by different terms
Here’s a list from Luke Muehlhauser:
“Related (and in some cases near-identical) concepts include the “web of prevention” (Rappert & McLeish 2007; Revill 2016), the “Swiss cheese model” (Reason 1990; Reason et al. 2006; Larouzee & Le Coze 2020), “layers of protection” (Center for Chemical Process Safety 2017), “multilayered defense” or “diversity of defense” (Chapple et al. 2018, p. 352), “onion skin” or “lines of defense” (Beaudry 2016, p. 388), or “layered defense” (May et al. 2006, p. 115).”
Add discussion of how this concept is relevant to existential risk in general or various specific existential risks, global catastrophic risks, existential risk factors, and/or risks of other negative trajectory changes
Things this could draw on include the Cotton‐Barratt, Daniel & Sandberg paper; footnote 19 from Muehlhauser; and https://forum.effectivealtruism.org/posts/emvBqtzYYRQwGrazx/the-web-of-prevention
I have in mind the concept’s relevance both to risk analysis and to risk mitigation
Maybe add discussion of how this concept has been applied in various mainstream (non-EA) fields/communities/etc.
This could again draw on footnote 19 from Muehlhauser
(Man, that’s a good footnote)
Look through some of the sources cited in the tagged posts, add some to the Bibliography here, and draw on ideas from some of them for the text of the entry itself