Thanks, Jim — that’s a thoughtful attempt to restate our terms, and it touches on something important you asked in the other thread about bandwidth–acuity vs range–resolution.

Our range concept maps fairly closely onto the welfare range used in Rethink Priorities’ Moral Weight project — it refers to the upper bound of affective intensity an organism can plausibly access .

Where we’d adjust is resolution. In the earlier draft your summary makes it sound like resolution is just “precision within a bounded range,” but that framing risks suggesting that resolution is always subordinate to range in motivational function. In fact, from a pure information-encoding perspective, resolution is as versatile as range for enabling intensity-based prioritization, because in principle both could be increased indefinitely: range by extending the extreme ends of the scale, and resolution by subdividing any given range into arbitrarily fine gradations. We develop this point in the The Function and Evolution of Affective Scales section of the Do primitive sentient organisms feel extreme pain?  paper

So the distinction isn’t “range = strength, resolution = detail”; it’s that range and resolution are two orthogonal axes along which affective systems can vary, each capable of supporting graded prioritization. A system with high resolution but modest range could still distinguish and act on nuanced motivational differences without accessing extreme affective intensities at all.

Thanks Jim

On the cost point you raised — “extra integration, valuation, and modulatory capacity are costly only if they decrease fitness in some way, right?” — selection indeed acts on net fitness. Still, it’s both useful and standard to keep costs and benefits analytically separate before recombining them. A trait can be costly in terms of resources or architecture even when it increases fitness overall; brains and immune systems are classic examples. 

On your footnote #3 — “the question of whether organisms with narrower welfare ranges could feel extreme pain” — I think there may be a bit of a contradiction in terms. If an organism has a genuinely narrower welfare range, then by definition (or at least under the operational definitions I’m using), it does not reach disabling or excruciating levels of negative affect. In that framing, the relevant question is precisely where the negative-intensity ceiling lies.

Thanks, Jim — that does get to the crux.

I think your scenario is plausible in principle: once an alarm is “loud enough,” further increases in intensity could be selectively neutral, so unnecessarily loud alarms might persist by drift, much like neutral variants in molecular evolution.

My hesitation is about how often extreme felt intensity actually falls into that neutral regime. For neutrality to hold, extra intensity must add no benefit and impose no additional costs or constraints. If affective states are whole-organism control states rather than simple sensory readouts, then escalating intensity plausibly requires extra integration, valuation, or modulatory capacity. In that case, intensity beyond “loud enough” would not be strictly neutral, and drift would be limited.

So I see neutral drift as a live alternative, but not the default. The framework is meant to clarify when neutrality is plausible versus when selection should instead cap, reshape, or avoid extreme intensity altogether.
 

Thanks, Vasco — I really appreciate that.

Yes, some dedicated funding would be very welcome to help expand and accelerate the comparative analysis of affective capacity. I have a few ideas I’d be keen to discuss once the follow-up piece is out and the framework is more fully specified.

Let’s definitely stay in touch — I’ll make sure to loop back..

Thanks, Itamar. I’m glad you found the framework useful, and thanks for laying out these concerns.

(1) On selection in life-or-death situations.
I’m less convinced that life-or-death contexts should be treated as marginal for evolutionary explanation. Many such hazards (e.g. fire, severe injury, predation) recur across generations, and even small increases in the probability of rapid withdrawal and survival can be strongly selected for. In that sense, excruciating pain in these contexts looks like a straightforward case of ordinary evolutionary logic at work, rather than a special case where costs become irrelevant or selection effectively “switches off.”

(2) On alternative mechanisms (linear transduction, hormones, etc.).
I’m very sympathetic to the idea of carefully considering non-adaptive explanations, since some features can indeed arise as byproducts of other selective pressures. I was an avid reader of Stephen Jay Gould, and The Spandrels of San Marco remains a classic reminder of this point. So I agree that high-intensity pain could arise largely as a byproduct of how damage signals scale at the sensory or cellular level, rather than because intensity itself was directly selected for. At the same time, this kind of “linear transduction” may itself carry adaptive value (i.e. function as an exaptation, again in Gould’s sense), since greater damage would naturally call for more urgent behavioral responses to stop it.

On the point about hormones or other system-wide mechanisms, I may be missing what you have in mind — I’d be very interested in a concrete example and in how you think it would change the cost–benefit picture.

Thanks a lot, Vasco — and thanks for the upvote!

You’re absolutely right to push us toward the practical question of how to compare affective capacity across species. That’s ultimately where this line of work needs to go. At the same time, we’ve been deliberately cautious here, because we think this is one of those cases where moving too quickly to numbers or rankings risks making the waters muddier rather than clearer.

Our sense is that the comparison of affective capacity across species hinges on a set of upstream scientific questions that are still poorly articulated- especially around when sentience arises at all, and when it plausibly extends to very intense affective states. The aim of this piece was to stress-test a way of structuring those questions before turning them into quantitative tools.

That said, we do see this as complementary to RP’s research agenda on valuing impacts across species. In fact, we think cost–benefit reasoning about sentience and affective intensity can help discipline some of the assumptions that go into moral-weight or welfare-capacity estimates, rather than replacing them.

We’re currently working on a follow-up that moves closer to a practical comparative framework, and we’re very much treating the present work as groundwork for that. Happy to loop back and share it once it’s ready — and we’d be keen to hear your thoughts then as well.

Thanks a lot for the kind words, Jim — and for the thoughtful pushback.

I think your point holds if we assume that the only way to implement a very strong alarm is via extreme felt intensity — but that assumption is exactly what we’re questioning.

I agree that in genuinely catastrophic situations, evolution should tolerate very “loud” alarms. The open question, though, is whether those alarms need to be implemented as extreme affective states, rather than through non-affective or lower-intensity control mechanisms.

On the benefit side, there seem to be two distinct roles a very strong signal could play. First, triggering an immediate reaction in life-or-death situations. But this doesn’t require affect at all: many organisms (including very simple ones) already show robust threat responses via non-felt control. Even in sentient organisms, immediate escape could in principle be driven by low-intensity affect if thresholds are set low enough, especially where behavioral options are limited.

Second, overriding other ongoing motivations in organisms with richer behavioral repertoires. Here, stronger affective signals become more plausibly useful, as they can reliably dominate competing drives (foraging, mating, self-maintenance, etc.). One way to achieve this is by expanding affective range rather than relying only on finer discrimination within a narrow range.

On the cost side, generating and sustaining very high-intensity affective states may plausibly require substantial architectural capacity of the kind we discuss above. In systems with limited computational or neural resources—and especially in organisms with few available behavioral options—extreme felt states may therefore be difficult or unnecessary to implement, regardless of how valuable a very loud alarm would be.

Thanks, Becca — really glad you took a look and liked it.

On your point about how this relates to certifications and similar tools: we see this as strongly complementary to them, not an alternative. When Welfare Footprint estimates become available, our hope is that they’ll be usable in many different ways by different stakeholders — including certification initiatives themselves — rather than being tied to a single interface or application.

This app is best understood as an early exploratory step: a way of seeing how people actually engage with welfare information, what resonates or causes confusion, and how different framings influence choices. We hope these insights can be useful not just for us, but for anyone thinking about how WFF-style estimates might be effectively deployed beyond a single app.

Thanks for spelling this out, Vasco — yes, that’s a fair clarification.

When we say that pain intensities are defined as “absolute” in WFF, this is meant in a conceptual and operational sense within a shared intensity vocabulary, not as a claim that no interspecific adjustments are needed in practice. The statement you quote is explicitly conditional (“if shrimps were capable of experiencing Excruciating pain”) and is held as a temporary, simplifying assumption to allow measurement of time spent in different intensity categories, while recognizing that the true placement of experiences on an absolute scale across taxa remains an open scientific problem.
 

At a personal scientific level, I find it very implausible that the affective capacity of a shrimp and that of a human are comparable. However, because this remains an unresolved empirical question, the framework itself is intentionally agnostic and requires that any interspecific adjustments be made explicitly and post-quantification, rather than being implicitly embedded in the core estimates.

Thanks, Vasco. We recognize that for most specific interspecies comparisons, affective capacity (not probability of sentience) is indeed crucial, but this remains an open scientific question. For that reason, the Welfare Footprint Framework is intentionally agnostic about correction values for interspecific scaling: welfare estimates are produced without such corrections, and any assumptions about differences in affective capacity must be applied explicitly and transparently as optional post-quantification adjustments when particular comparisons require them, rather than being implicitly folded into the core estimates.