William MacAskill

It's great that some young philosophers write for a general audience. If I understood the author correctly, this book is basically an introduction to his own field of research, a line of inquiry he calls "longtermism". In short, its purpose is to study present-day choices in light of future generations' wellbeing (or their moral rights, I suppose, but moral theory is not included in this book).

I should preface my criticism by saying that I generally liked the book and thought that it contained good nuggets of wisdom. But the writing is restless especially in the first 100 pages of the book (parts 1 and 2). I appreciate that the author is well-read in both history and science, but he's so eager to demonstrate it that he sometimes skips between three different topics on a single page. Expected value theory, the history of slavery, biological and cultural evolution, human prehistory, ancient Chinese philosophy and artifical intelligence are all blended into a presentation which circles around a few simple ideas (the general idea of longtermism, and value lock-in). I think these ideas could have been explained better with a more focused introduction. This might also have left some space for some speculative questions: what kind of political arrangements could we ideally implement to avoid premature value lock-in? How would we know when our values are mature enough to be locked? And can we even deliberately lock them if we wanted to?

Fortunately, the author finds his focus in the second half of the book. I find it interesting that many of the long-term threats he identifies have figured so prominently in the daily news cycle of the 2020s: pandemics, climate change, artifical intelligence. Just for comparison, overpopulation was considered a massive problem in the 1990s, but not today (the author in fact advocates active procreation). I think the author's putatively broad viewpoint is myopic, and that either none or just one of these three threats will be considered severe by the end of this century. More importantly, I was a little disappointed that authoritarian politics, which I would consider the biggest threat since it stifles all moral action, is only mentioned briefly in passing. But I could of course be wrong.

Speaking of being wrong, the book contains many statements like this: "my colleague Toby Ord puts the risk of human extinction this century from engineered pandemics at around 3 percent" (page 162). Based on what? This can only be a wild guess. There is no computer simulation which models all of human society with accuracy. It is therefore senseless to pretend that you can assess the probability of an event which is contingent on the actions of a small number of people, or maybe even a single person (a bioscientist-turned-terrorist). The author frequently presents some random number as an educated guess ("I think the risk of this is x %"), even though it must, by definition, an uneducated one. I understand that this extreme simplification serves a political "we must take action" purpose, but it's still intellectually dishonest.

The chapter on civilizational collapse is interesting and original, but the author thinks very much like an engineer. The discussion focuses solely on the availability of physical resources for post-collapse populations. The author ponders whether or not they would be able to redevelop technologies starting from a low level. A social-scientific and political perspective would have been a lot more interesting: how should these populations organize themselves (would monarchy be best)? Is there any way to reduce the risk of war between surviving populations? It might also not be a foregone conclusion that present-day knowledge would be preserved in the collapse, particularly the tacit agricultural knowledge that farmers pass on from generation to generation. The author's engineering perspective is unnecessarily narrow.

Part four was the one I enjoyed the most. Here the author actually engages in some philosophy when he discusses various alternative living standard scenarios for the long-term future. I found particular personal gratification in the author's advocation of procreation in the final chapter of the book. I have found it regrettable that many environmentalists consider it their moral duty not to have children. The logical conclusion is that the next generation will be raised by people who are not environmentalists. This question is actually a good illustration of an everyday decision which looks quite different in a longtermist perspective.

In conclusion, I can see this book doing a lot of good in the near future. I the long term, I hope it will be surpassed by better works on the subject.… (más)