Hi Nick. Thanks for the kind words about the MWP. We agree that it would be great to have other people tackling this problem from different angles, including ones that are unfriendly to animals. We've always said that our work was meant to be a first pass, not the final word. A diversity of perspectives would be valuable here.

For what it’s worth, we have lots of thoughts about how to extend, refine, and reimagine the MWP. We lay out several of them here. In addition, we’d like to adapt the work we’ve been doing on our Digital Consciousness Model for the MWP, which uses a Bayesian approach. Funding is, and long has been, the bottleneck—which explains why there haven’t been many public updates about the MWP since we finished it (apart from the book, which refines the methodology in notable ways). But if people are interested in supporting these or related projects, we’d be very glad to work on them.

I’ll just add: I’ve long thought that one important criticism of the MWP is that it’s badly named. We don’t actually give “moral weights,” at least if that phrase is understood as “all things considered assessments of the importance of benefiting some animals relative to others” (whether human or nonhuman). Instead, we give estimates of the differences in the possible intensities of valenced states across species—which only double as moral weights given lots of contentious assumptions. 

All things considered assessments may be possible. But if we want them, we need to grapple with a huge number of uncertainties, including uncertainties over theories of welfare, operationalizations of theories of welfare, approaches to handling data gaps, normative theories, and much else besides. The full project is enormous and, in my view, is only feasible if tackled collaboratively. So, while I understand the call for independent teams, I’d much prefer a consortium of researchers trying to make progress together.

Someone should commission new moral weights work in the next year

I’d like to see it expanded to even smaller animals if possible, like @Vasco Grilo🔸 asks here.

I'm not an expert on moral weights research itself, but approaching this rationally, I’m strongly in favour of commissioning an independent, methodologically distinct reassessment of moral weights—precisely because a single, highly-cited study can become an invisible “gravity well” for the whole field.

Two design suggestions that echo robustness principles in other scientific domains:

1. Build in structured scepticism.
   Even a small team can add value if its members are explicitly chosen for diverse priors, including at least one (ideally several) researchers who are publicly on record as cautious about high animal weights. The goal is not to “dilute” the cause, but to surface hidden assumptions and push every parameter through an adversarial filter.
2. Consider parallel, blind teams.
   A light-weight version of adversarial collaboration: one sub-team starts from a welfare-maximising animal-advocacy stance, another from a welfare-sceptical stance. Each produces its own model and headline numbers under pre-registered methods; then the groups reconcile differences. Where all three sets of numbers (Team A, Team B, RP) converge, we gain confidence. Where they diverge, at least we know which assumptions drive the spread.

The result doesn’t have to dethrone RP; even showing that key conclusions are insensitive to modelling choices (or, conversely, highly sensitive) would be valuable decision information for funders.

In other words: additional estimates may not be “better” in isolation, but they increase our collective confidence interval—and for something as consequential as cross-species moral weights, that’s well worth the cost.

I'm not sure it needs a whole other large project, especially one started from scratch. You could just have a few people push further on these points, which seem like the most likely cruxes:

1. Further developing and defending measures that scale with neuron counts.
2. Assessing animals on normative stances besides expectational hedonistic utilitarianism.
3. Defending less animal-friendly responses to the two envelopes problem (see prior writing and the comments here, here, here, here, here and here).
4. EDIT, also: Assessing the probability that invertebrates of interest (and perhaps other animals of interest) can experience excruciating or unbearable pain, as effectively all-consuming pain an animal would be desperate and take incredible risks to avoid.

And then have them come up with their own models and estimates. They could mostly rely on the studies and data RP collected on animals, although they could check the ones that seem most cruxy, too.

I'd like to see a few more surveys on moral weights, with larger samples of both animal welfare experts and lay people, than this small one (n=100) I conducted in Belgium https://brill.com/view/journals/jaae/7/1/article-p91_6.xml