‘Existential risk’ has become something of a cause célèbre in the last decade. Research centres dedicated to ‘The Future of Humanity’, several of which are funded by eccentric billionaires, have sprung up around the globe: at Oxford (where Ord works), at Cambridge, in Boston, and at Berkeley. The Precipice is a manifesto – one might even say, a bible – for the mathematicians, physicists, computer scientists, and philosophers that populate the boards of these institutes. Ord argues for the moral importance of defending humanity’s long-term future and makes an impressive start on identifying and categorising various existential risks. Ord considers both natural risks – in the form of globe-shattering asteroids and comets, ‘super volcanoes’, nearby stars exploding, and other more esoteric cosmological events – and man-made risks, such as nuclear war, global heating, ‘super-intelligences’, and pandemics.

In each case, Ord tries to estimate the magnitude of the risk and to identify actions we might take to prevent, or at least manage, it. In most cases, in the short term, that turns out to be the traditional academic conclusion ‘more research required’, although, to be fair, getting governments to do even that much to protect the long-term future of humanity would be an achievement. In relation to the risk of nuclear war and engineered pandemics, Ord has some sensible, if modest, suggestions for strengthening international institutions to try to reduce the risks of catastrophe owing to these causes.

Toby Ord, 2019 (David Fisher)

However, when it comes to other risks stemming from technology, especially the risk associated with the pursuit of AI, Ord seems to lack the courage of his convictions, arguing only that we should ‘proceed with caution’. Like others who want to alert us to the dangers of new technologies, without threatening the material interests of the companies that champion them and that are often sponsoring the conferences or institutes at which concerns about new technologies are being raised, Ord suggests that we can’t stop new technologies from being developed: it would only take a few rogue actors flouting any ban on a technology to bring it into existence. However, if this is true, it is equally a problem for proposals for regulation of new technologies, whenever regulation would stand in the way of profit or national interest – which is to say precisely when it is important. Consequently, the choices we face in response to the risks posed by new technologies are more difficult than Ord admits.

One of the pleasures of reading The Precipice is watching Ord reveal himself as a prodigious polymath. The book ranges across the natural sciences – including geology, physics, and cosmology – as well as economics, history, and philosophy. The writing is clear, the tone ringing, and Ord buttresses his claims with extensive notes, sources, and several appendices, which together take up nearly half of the manuscript.

Inevitably, the reader is required to take many of Ord’s claims on trust. The book also illustrates one of the difficulties of doing applied philosophy, which is getting the balance right between offering something to address a real-world concern and following ideas where they lead. For many people, I suspect, the immediate risks they face – starvation, disease, civil war, rape – mean that they have no time to consider the long-term survival of humanity. Yet Ord argues that addressing existential risks is one of most pressing challenges of our time. This conclusion follows swiftly from that fact that Ord believes that we should only discount the interests of future people to the extent that we are uncertain whether they will exist or not. According to Ord, this means: ‘Almost all of humanity’s life lies in the future, almost everything of value lies in the future as well: almost all the flourishing; almost all the beauty; our greatest achievements; our most just societies; our most profound discoveries.’

Indeed, the scale and scope of the future The Precipice is concerned with is so large that Ord cannot prevent himself from launching into occasional flights of philosophical fantasy, such as when he suggests that disputes between different schools of philosophy could be resolved by allowing each to colonise different galaxies! Moreover, although Ord denies this, his argument risks the conclusion that we should abandon all our current worldly concerns for the sake of the well-being of those who will live in this distant future.

Even more problematically, Ord’s focus on existential risk itself risks distracting our attention from disasters short of extinction, which are arguably more pressing. This is especially true of the book’s treatment of the climate crisis. Ord suggests that, although it would be an ‘unparalleled human and environmental tragedy,’ even an extreme of 20° C of warming is unlikely to cause our extinction. Given the pace at which global heating is occurring, and the scale of the disasters that have resulted from just the 1° C warming that we have already experienced, this strikes me as small comfort.

That being said, both the looming catastrophe of global heating and the risk of a pandemic of the sort we are currently experiencing were predicted decades ago. Governments, and the global community more generally, didn’t take these risks sufficiently seriously at the time and failed to do what was required to avert them. The Precipice is a clarion call that we should not make the same mistake again when it comes to the other risks that threaten life on planet Earth. I only hope we heed it.