The moral light cone

I have a review of Jeff Sebo’s The Moral Circle forthcoming in Ethics, Policy, & Environment. I think it’ll be a while until it sees the light of day, so here’s an excerpt:

There are approximately ten quintillion (10x10¹⁸) insects on Earth, and Jeff Sebo talks about all of them … in just over 180 pages. Moreover, we should care about them (to some degree). And not just insects, but other invertebrates and digital beings, including artificial intelligence (AI) systems, whose numbers are potentially limitless. It’s no longer an expanding but an exploding moral circle …, a cosmic bang.

One of the book’s basic premises is that there are some things we know and many we don’t. We know some basic moral principles. We can also estimate many probabilities, with more or less precision—and how confident we are in our estimates affects how we should approach different cases. Uncertainty, instead of paralyzing us, should force us to adopt a flexible framework to determine who and what counts, in what ways, and to what degree. More fundamentally, it is because we don’t know some things that we know that we should treat certain beings better. The explosion of the moral circle is therefore not so much a reflection of our increased knowledge … but of our increased moral caution.

Another basic premise is that many kinds of nonhumans could have moral status. We cannot presume that humans will always take priority; indeed, Sebo will argue they should not. From this and from particular observations about other entities (including probability estimates of the sentience of, say, flies or worms), we can conclude that a whole range of entities matter, from cats and dogs to cuttlefish and honeybees, from chickens and pigs to androids and AIs. At the very least, all of those might matter. And knowing that they might, it’s well-advised to treat them like they do.

The book is a lot of fun, important, and very accessible. You should read it. In this post I’d like to expand on a brief note I make in the review concerning the metaphor of the moral circle, which has been a mainstay of discussions in environmental ethics and animal ethics for decades.

The moral circle is meant to illustrate the structure of the moral community, the set of entities that matter morally in their own right—all the things we morally ...