Great post. As you point out, this is one of the important unresolved questions in science, and much more research aimed at generating relevant evidence is needed.
Meanwhile, I find the evolutionary perspective especially useful at this stage, so I wanted to raise one disagreement with the claim that there is “every evolutionary reason” for relatively simple organisms to feel intense pain. The adaptive value of a rapid and dramatic response does not, by itself, tell us how intense the underlying felt state must be. Reflexive behavior, for example, can be rapid and dramatic without involving affective experience at all. Even in a sentient organism, a strong behavioral response could be triggered by a low response threshold rather than by an extremely intense felt state.
Framed as a cost–benefit question, I therefore do not think evolutionary reasoning alone makes high-intensity pain in simpler sentient organisms the parsimonious default. We explored that broader perspective here.
Briefly, affective scales help organisms prioritize among competing needs and actions. Organisms with simpler nervous systems are expected to have more limited behavioral repertoires and fewer competing motivations, in which case a lower-resolution affective scale may be sufficient. Organisms with richer behavioral and cognitive repertoires, by contrast, needs to integrate a much larger set of memories, sensory inputs, and competing priorities.
Lower resolution does not by itself imply a narrow affective range. But expanding the range to include extreme states is only one possible way of producing urgent behavioral prioritization. All else being equal, selection should favor a less costly mechanism when it provides the same functional benefit. Very high affective intensity probably involves additional energetic, physiological, or architectural demands
Taken together, these considerations do not rule out intense pain in insects or decapods. But evolution makes high-intensity pain an important hypothesis to investigate, not a default conclusion (We explored the distinction between affective range and resolution more directly here).
Thanks, Vasco. I had already acknowledged that the analogies were no longer helping, and then I fell into offering another one, so I concede that mistake. I do not think my underlying point is coming across, but I have laid it out as clearly as I can in our exchange. But just addressing your questions:
If one organism truly had affective experience and the other did not, the ceiling analysis would apply only to the former. For the latter, an affective ceiling would be inapplicable, not merely lower. If we could not tell which was which, the tool should reflect that uncertainty and proceed only conditionally.
(One clarification: this sentience gate belongs to our experimental Ψ approach, not to the core WFF).
Your final question captures the crux: if I regarded sentience as merely a matter of human convention, I would not retain it as a scientific gate. My position, as I mentioned before, is that whether anything feels good or bad is a real fact about the organism, even when we cannot determine it confidently.
Thanks, Vasco. I think your final paragraph shows that our positions are now closer than they initially appeared, and that part of the disagreement came from asking the word sentience to do two different jobs: describe whether affective experience is present, and determine whether an entity has non-zero moral value. In our tool, it is used only in the first sense.
On the scientific question, yes: under a categorical account of sentience, arbitrarily small changes near the relevant biological threshold could in principle place otherwise extremely similar organisms on opposite sides of it. I do not regard this as incoherent. Continuous underlying variables can produce categorical system-level events; a neuron, for example, may or may not fire an action potential as its membrane potential crosses a threshold. This analogy does not establish that sentience is categorical, but it shows that gradual biological change does not rule out a categorical onset.
The sentience gate in our tool therefore does not assign moral worth. It asks whether welfare-relevant affective experience is plausible enough for an affective-ceiling analysis to be meaningful. Whether entities without sentience may nevertheless have moral value, or whether moral status should vary continuously, are separate normative questions.
So perhaps our remaining scientific disagreement is now quite narrow: whether the minimal presence of affective experience is itself graded or categorical. On almost everything surrounding that boundary, however, we seem to agree: the biological capacities supporting sentience, our evidence for it, and the affective range, resolution, and intensity that follow are all graded. That is quite a lot of common ground! :) Thanks, Vasco, for the careful and constructive exchange.
Thanks, Vasco. I think our respective positions are now becoming quite clear, and we may be reaching the point where further progress depends more on scientific and theoretical work than on extending the analogies.
My exoplanet example was intended only to distinguish graded evidence from the underlying fact being investigated. Whether a candidate celestial body exists is different from whether an already known body satisfies one of several proposed definitions of a planet. Margot’s figure addresses the latter question. My analogy concerned the former.
As I noted above, my position is that the biological capacities supporting sentience (and our evidence about them) can vary continuously even if the minimal presence of affective experience is categorical. What I would add here is that gradual evolution does not make such a transition implausible. Existing structures and capacities can be co-opted into a new functional role, as captured by the concept of exaptation: a feature that originally evolved for one function, or for no particular function, may later acquire another. This may make the evolutionary onset of sentience especially difficult to locate, because there need not be an obvious biological marker separating the earliest sentient organisms from their closest non-sentient relatives. The transition may have depended on a very small biological change, or even on a change in context that allowed existing mechanisms to perform a new role.
So yes: under my hypothesis, two organisms could in principle be extremely similar while affective experience was present in one and absent in the other. I do not find that paradoxical. A small difference in a complex system can sometimes make a new causal process possible. The supporting architecture may vary continuously even though the process we are asking about either occurs or does not occur in a particular organism at a particular time.
Your concern about one organism receiving some moral value while the other receives exactly none introduces a separate normative question. That conclusion does not follow automatically from the claim that sentience is categorical. The sentience gate in the tool is not intended to assign moral worth. Its focus is narrower—and appropriately so, given that it concerns one of the biggest mysteries in science: it asks whether affective states, and therefore sentience in the relevant sense, plausibly occur in the target taxon.
Turning to the normative question, assuming that every organism has more than exactly zero moral value is a possible normative position, but it is not a scientific consequence of treating biological capacities as continuous. It would require its own justification.
Speaking only for myself—and separately from the analytical commitments of the Welfare Footprint Framework—my principal concern is severe suffering, particularly Disabling and Excruciating Pain. Annoying and Hurtful experiences remain genuine components of welfare and should be recorded in WFF analyses. But the presence of lower-intensity negative affect alone would not ordinarily make an organism or intervention a leading priority for me, especially given the scale of severe suffering that already exists and the need to consider where effective intervention is possible.
This is one reason the affective-ceiling question matters so much to me. Nature is not benign, and neither are most modern animal-production systems. Given the scale of severe suffering that already exists, I think our attention should be concentrated where the most intense suffering is possible. If biologically simpler sentient organisms have narrow affective ranges and cannot experience severe Pain, I would find that reassuring.
I therefore think our remaining disagreement concerns at least two distinct questions. Scientifically, you favor treating sentience itself as graded, whereas I regard its minimal presence as categorical while treating our evidence—and subsequent affective range, resolution, and intensity—as graded. Normatively, you favor assigning every organism more than zero moral value, whereas my own priorities are concentrated on organisms capable of severe suffering, particularly where meaningful intervention is possible.
I should first clarify whose position is being discussed: The Welfare Footprint Framework itself does not prescribe a particular theory of sentience or affective capacity. It treats positive and negative affective experiences as the core of welfare, but it remains open about the precise biological mechanisms that produce them and about how affective capacities should ultimately be compared across species. The ideas in this series of posts are therefore better understood as our provisional contribution to this problem, developed largely for the practical purpose of making interspecific Welfare Footprint comparisons possible. They should not be presented as an official WFF position on whether sentience is categorical or graded.
My own personal view is that the biological capacities associated with sentience can vary continuously, while the minimal presence of affective experience is categorical. Nociception, memory, learning, integration and considerable information-processing capacities may all have existed in pre-sentient ancestors. My hypothesis is that, at some point, affective states became part of the control system, providing a common currency through which signals and memories could be valued and used to guide behaviour. Under this view, there is a difference between a system in which something can feel good or bad and one in which nothing does, even though the capacities supporting that transition and the affective capacities that follow it are graded.
An analogy would be an exoplanet candidate. Astronomers may have evidence of varying strength that a planet exists around a distant star. Their confidence may be 20%, 70% or 99%, but the planet itself either exists or does not. Graded evidence does not require the underlying fact to be graded.
Likewise, the fact that behavioural, neural and physiological evidence exists on continua does not by itself imply that sentience must exist on a continuum. It means that our confidence about its presence is graded. This not requires assuming a simple or already known boundary in the evidential space. The biological transition may be complex, and we may be deeply uncertain about where it lies.
In your hypothetical, if we had both complete physical evidence and an adequate biological account of which forms of organization generate affective states, then yes: under my working view, the answer for a particular organism at a particular time would be either that affective experience was present or that it was absent. Our proposed classifications reflect our incomplete evidence and incomplete biological understanding, not a claim that the organism is partially sentient in proportion to our confidence.
This is also why the tool uses a sentience-plausibility gate followed by a separate affective-capacity analysis. The first asks whether there is sufficient reason to infer that anything can feel good or bad for the organism. The second asks, conditional on that, how differentiated and intense those states could be. The first is treated categorically in the underlying hypothesis but uncertain in our knowledge; the second is explicitly graded.
Thanks, Vasco — this is a very interesting challenge, and the pieces by Kammerer and Frankish are highly relevant.
I am not sure, however, that our use of sentience depends on the traditional conception of phenomenal consciousness that you are criticizing. In the Welfare Footprint Framework, the relevant question is whether an organism can have positive or negative affective states—states that can make its situation better or worse for it. We try to infer those states from converging behavioural, physiological, neural, pharmacological, cognitive, evolutionary, and ecological evidence.
This is why I would hesitate to focus only on what an organism can do. Behaviour and functional capacities are important evidence, but they are not themselves welfare. A biological or artificial system may avoid damage, learn, prioritize certain outcomes, and change its behaviour without anything necessarily feeling good or bad for it. The distinction between affective and non-affective control is therefore part of the question we are trying to investigate, rather than something we can simply set aside.
I would also hesitate to describe the empirical proxies as arbitrary. They are indirect and uncertain, and their interpretation depends partly on one’s theory of consciousness. But some proxies are clearly more informative than others. Their value can be assessed through causal and comparative evidence, experimental interventions, and whether different classes of indicators point toward the same conclusion.
That said, your comment suggests a useful improvement to the tool. We could define the sentience gate more carefully and make clearer that it is not trying to identify an ineffable property disconnected from observable biological processes.
The workflow itself would remain the same. First, we ask whether the available evidence supports the existence of any positive or negative affective states. Only then, conditional on that assessment, do we ask how intense those states could plausibly become. These are related but distinct questions: the sentience gate concerns whether there is any affective welfare subject at all, whereas the ceiling analysis concerns the upper limit of that subject’s affective range.
Some of the same evidence may inform both stages, but the inferential targets are different. We could make this distinction clearer in the article and in the tool, while also separating the observable evidence from the further inference about affective experience at each stage.
Someone sympathetic to Frankish’s view might interpret the same evidence without appealing to phenomenal properties as traditionally conceived. But for the WFF, we still need to distinguish systems that merely process information and regulate behaviour from organisms for which conditions can plausibly feel better or worse.
Thank you for drawing our attention to this. I think it may help us clarify both the article and the tool without changing the basic sequence of the analysis, and without requiring us to settle the broader philosophical debate before making practical progress.
Thanks, Jim! I think Dolores/Mildred is actually a very helpful toy example.
If both Dolores and Mildred already cross the threshold needed to lexically prioritize starvation, then Dolores’s stronger feeling may indeed add no extra functional value. That’s very close to the point we tried to make in the revised Figure 1 of Do primitive sentient organisms feel extreme pain?: two systems can differ in range while still being equally effective for prioritization, provided the relevant discriminative structure is the same.
So yes: in your setup, the extra intensity could be selectively neutral if it also carries no extra costs or constraints. That’s where the framework still bites. Our point isn’t that higher intensity must always be selected against, but that it shouldn’t automatically be treated as either necessary or neutral.
On your second point, I also agree that we should be careful: I would not want to claim, as a general rule, that “more intense” always means “more expensive.” The more modest claim is that some ways of implementing very high intensity may require broader integration, stronger modulation, or greater whole-system involvement, and if they do not, then your neutrality story remains a live possibility (even if it is not the default expectation in the framework).
This is also part of why we’ve been trying to make these distinctions more explicit in the more recent Interspecific Affect GPT post: not because it settles cases like this, but because it forces us to state more explicitly where the ceiling question depends on extra commitments, where neutrality remains a serious live possibility, and how this kind of reasoning can be pushed toward real taxa - something that matters directly for interspecific comparisons of the capacity to feel pain.
Since writing this post, our thinking on this work has evolved in a few important ways.
In particular, what we originally referred to as the Pain Atlas Project is now better understood as part of a broader effort: the development of a Welfare Footprint Atlas. The goal is to enable the generation of structured, comparable, and inspectable estimates of animal welfare across products, production systems, and species.
The key shift is not simply the use of AI, but the ability to produce first-pass estimates at scale, making it easier to identify where suffering is concentrated and where interventions may have the greatest impact — while keeping assumptions explicit and open to revision.
We’ve updated the main text of the post to reflect this evolution, and we’re continuing to develop the underlying tools and methods that make this possible.
Thanks Vasco — that’s a reasonable concern, but I think it assumes a stronger claim than the framework is actually making.
We are not attempting to define a finely resolved ratio scale covering the entire possible range of pain intensities across taxa. The four intensities are intended as coarse phenomenological anchors, chosen as a practical balance between resolution and scientific tractability.
“we focus on (i) the importance of the pain signal to promote adaptive behaviors and (ii) the disruptive character of the pain experience to classify pain into four discrete categories of intensity [46]. The number of categories was devised to represent a good balance between scientific tractability and resolution, though there is no impediment to the creation of categories intermediate to those presented. Categorizing pain instead of measuring it on a numerical scale of intensity also prevents us from forcing ratings that may not necessarily be linear onto a linear scale.”
So the goal is not to cover the entire theoretical intensity range with fine granularity, but to provide a small number of biologically interpretable categories that can be applied with reasonable consistency. Adding many more levels would only be an improvement if they could be assigned reliably; otherwise it would risk creating false precision.
And importantly, the framework is not committed to four categories as a final solution. If future work supports a better-validated scale with additional intermediate levels, those could be incorporated without difficulty. For now, four levels seem to provide a workable and defensible balance between usability and epistemic caution.
I recently came across this video clip where Michael Pollan argues that artificial systems cannot be conscious. His argument touches on several themes relevant to this post—specifically the conditions for the origin of sentience—but I believe it rests on a fundamental logical error.
Pollan’s core claim is that because feelings originate in the brainstem (a point that is scientifically sound) and are tied to biological vulnerability, they are inherently biological and cannot arise in artificial systems. His logic follows this structure:
Feelings originate in the brainstem.
The brainstem is biological tissue.
Therefore, only biological systems can feel.
This reasoning confuses evolutionary origin with functional requirement. Evolutionary history explains how a trait first appeared given the constraints of carbon-based nervous systems; it does not dictate the physical substrates capable of implementing that functional organization.
The "Feather Analogy" illustrates the flaw perfectly:
Birds fly using feathers.
Feathers are biological.
Conclusion: Airplanes cannot fly.
Clearly, the conclusion is false. If the brainstem's "feelings" are essentially the integration, valuation, and prioritization of internal states—all of which are computational processes—then the relevant question is whether that functional architecture can be implemented in non-biological substrates.
Pollan’s second argument—that sentience begins with "feelings" rather than "thoughts"—is again, backed by solid science. However, he then lapses into what I can only describe as a "word salad" regarding biological vulnerability. He claims feelings "have no weight" and require a mortal, sensible body. This ignores a crucial neurological fact: affective states do not require peripheral sensory input. For example:
Clinical Depression: A profound affective state that can emerge entirely from neurochemical and structural patterns in the brain, independent of external "vulnerability."
Phantom Limb Pain: A vivid "feeling" of pain occurring in the absence of the actual biological body part.
These examples suggest that "feeling" is a representational state within a processing system. Crucially, we should not assume that affective states emerge only when there is a functional need for self-monitoring or goal-valuation. Instead, it is highly plausible that valence and sentience are emergent properties of the information-processing itself.
If a system architecture reaches a certain level of complexity and integration, the resulting "feelings" are ontologically real. To dismiss these states as "less real" because they lack a biological anchor or a "vulnerable body" is a category error; the reality of the experience is a property of the system's internal organization, not its hardware’s chemistry.
Bottom line: Pollan mistakes the "wetware" of our specific evolutionary path for the universal requirements of consciousness. From a welfare perspective, the possibility of sentience in digital minds remains a robust—and high-stakes—concern.
Great post. As you point out, this is one of the important unresolved questions in science, and much more research aimed at generating relevant evidence is needed.
Meanwhile, I find the evolutionary perspective especially useful at this stage, so I wanted to raise one disagreement with the claim that there is “every evolutionary reason” for relatively simple organisms to feel intense pain. The adaptive value of a rapid and dramatic response does not, by itself, tell us how intense the underlying felt state must be. Reflexive behavior, for example, can be rapid and dramatic without involving affective experience at all. Even in a sentient organism, a strong behavioral response could be triggered by a low response threshold rather than by an extremely intense felt state.
Framed as a cost–benefit question, I therefore do not think evolutionary reasoning alone makes high-intensity pain in simpler sentient organisms the parsimonious default. We explored that broader perspective here.
Briefly, affective scales help organisms prioritize among competing needs and actions. Organisms with simpler nervous systems are expected to have more limited behavioral repertoires and fewer competing motivations, in which case a lower-resolution affective scale may be sufficient. Organisms with richer behavioral and cognitive repertoires, by contrast, needs to integrate a much larger set of memories, sensory inputs, and competing priorities.
Lower resolution does not by itself imply a narrow affective range. But expanding the range to include extreme states is only one possible way of producing urgent behavioral prioritization. All else being equal, selection should favor a less costly mechanism when it provides the same functional benefit. Very high affective intensity probably involves additional energetic, physiological, or architectural demands
Taken together, these considerations do not rule out intense pain in insects or decapods. But evolution makes high-intensity pain an important hypothesis to investigate, not a default conclusion (We explored the distinction between affective range and resolution more directly here).
Good to debate this topic!
Thanks, Vasco. I had already acknowledged that the analogies were no longer helping, and then I fell into offering another one, so I concede that mistake. I do not think my underlying point is coming across, but I have laid it out as clearly as I can in our exchange. But just addressing your questions:
If one organism truly had affective experience and the other did not, the ceiling analysis would apply only to the former. For the latter, an affective ceiling would be inapplicable, not merely lower. If we could not tell which was which, the tool should reflect that uncertainty and proceed only conditionally.
(One clarification: this sentience gate belongs to our experimental Ψ approach, not to the core WFF).
Your final question captures the crux: if I regarded sentience as merely a matter of human convention, I would not retain it as a scientific gate. My position, as I mentioned before, is that whether anything feels good or bad is a real fact about the organism, even when we cannot determine it confidently.
Thanks, Vasco. I think your final paragraph shows that our positions are now closer than they initially appeared, and that part of the disagreement came from asking the word sentience to do two different jobs: describe whether affective experience is present, and determine whether an entity has non-zero moral value. In our tool, it is used only in the first sense.
On the scientific question, yes: under a categorical account of sentience, arbitrarily small changes near the relevant biological threshold could in principle place otherwise extremely similar organisms on opposite sides of it. I do not regard this as incoherent. Continuous underlying variables can produce categorical system-level events; a neuron, for example, may or may not fire an action potential as its membrane potential crosses a threshold. This analogy does not establish that sentience is categorical, but it shows that gradual biological change does not rule out a categorical onset.
The sentience gate in our tool therefore does not assign moral worth. It asks whether welfare-relevant affective experience is plausible enough for an affective-ceiling analysis to be meaningful. Whether entities without sentience may nevertheless have moral value, or whether moral status should vary continuously, are separate normative questions.
So perhaps our remaining scientific disagreement is now quite narrow: whether the minimal presence of affective experience is itself graded or categorical. On almost everything surrounding that boundary, however, we seem to agree: the biological capacities supporting sentience, our evidence for it, and the affective range, resolution, and intensity that follow are all graded. That is quite a lot of common ground! :) Thanks, Vasco, for the careful and constructive exchange.
Thanks, Vasco. I think our respective positions are now becoming quite clear, and we may be reaching the point where further progress depends more on scientific and theoretical work than on extending the analogies.
My exoplanet example was intended only to distinguish graded evidence from the underlying fact being investigated. Whether a candidate celestial body exists is different from whether an already known body satisfies one of several proposed definitions of a planet. Margot’s figure addresses the latter question. My analogy concerned the former.
As I noted above, my position is that the biological capacities supporting sentience (and our evidence about them) can vary continuously even if the minimal presence of affective experience is categorical. What I would add here is that gradual evolution does not make such a transition implausible. Existing structures and capacities can be co-opted into a new functional role, as captured by the concept of exaptation: a feature that originally evolved for one function, or for no particular function, may later acquire another. This may make the evolutionary onset of sentience especially difficult to locate, because there need not be an obvious biological marker separating the earliest sentient organisms from their closest non-sentient relatives. The transition may have depended on a very small biological change, or even on a change in context that allowed existing mechanisms to perform a new role.
So yes: under my hypothesis, two organisms could in principle be extremely similar while affective experience was present in one and absent in the other. I do not find that paradoxical. A small difference in a complex system can sometimes make a new causal process possible. The supporting architecture may vary continuously even though the process we are asking about either occurs or does not occur in a particular organism at a particular time.
Your concern about one organism receiving some moral value while the other receives exactly none introduces a separate normative question. That conclusion does not follow automatically from the claim that sentience is categorical. The sentience gate in the tool is not intended to assign moral worth. Its focus is narrower—and appropriately so, given that it concerns one of the biggest mysteries in science: it asks whether affective states, and therefore sentience in the relevant sense, plausibly occur in the target taxon.
Turning to the normative question, assuming that every organism has more than exactly zero moral value is a possible normative position, but it is not a scientific consequence of treating biological capacities as continuous. It would require its own justification.
Speaking only for myself—and separately from the analytical commitments of the Welfare Footprint Framework—my principal concern is severe suffering, particularly Disabling and Excruciating Pain. Annoying and Hurtful experiences remain genuine components of welfare and should be recorded in WFF analyses. But the presence of lower-intensity negative affect alone would not ordinarily make an organism or intervention a leading priority for me, especially given the scale of severe suffering that already exists and the need to consider where effective intervention is possible.
This is one reason the affective-ceiling question matters so much to me. Nature is not benign, and neither are most modern animal-production systems. Given the scale of severe suffering that already exists, I think our attention should be concentrated where the most intense suffering is possible. If biologically simpler sentient organisms have narrow affective ranges and cannot experience severe Pain, I would find that reassuring.
I therefore think our remaining disagreement concerns at least two distinct questions. Scientifically, you favor treating sentience itself as graded, whereas I regard its minimal presence as categorical while treating our evidence—and subsequent affective range, resolution, and intensity—as graded. Normatively, you favor assigning every organism more than zero moral value, whereas my own priorities are concentrated on organisms capable of severe suffering, particularly where meaningful intervention is possible.
I should first clarify whose position is being discussed: The Welfare Footprint Framework itself does not prescribe a particular theory of sentience or affective capacity. It treats positive and negative affective experiences as the core of welfare, but it remains open about the precise biological mechanisms that produce them and about how affective capacities should ultimately be compared across species. The ideas in this series of posts are therefore better understood as our provisional contribution to this problem, developed largely for the practical purpose of making interspecific Welfare Footprint comparisons possible. They should not be presented as an official WFF position on whether sentience is categorical or graded.
My own personal view is that the biological capacities associated with sentience can vary continuously, while the minimal presence of affective experience is categorical. Nociception, memory, learning, integration and considerable information-processing capacities may all have existed in pre-sentient ancestors. My hypothesis is that, at some point, affective states became part of the control system, providing a common currency through which signals and memories could be valued and used to guide behaviour. Under this view, there is a difference between a system in which something can feel good or bad and one in which nothing does, even though the capacities supporting that transition and the affective capacities that follow it are graded.
An analogy would be an exoplanet candidate. Astronomers may have evidence of varying strength that a planet exists around a distant star. Their confidence may be 20%, 70% or 99%, but the planet itself either exists or does not. Graded evidence does not require the underlying fact to be graded.
Likewise, the fact that behavioural, neural and physiological evidence exists on continua does not by itself imply that sentience must exist on a continuum. It means that our confidence about its presence is graded. This not requires assuming a simple or already known boundary in the evidential space. The biological transition may be complex, and we may be deeply uncertain about where it lies.
In your hypothetical, if we had both complete physical evidence and an adequate biological account of which forms of organization generate affective states, then yes: under my working view, the answer for a particular organism at a particular time would be either that affective experience was present or that it was absent. Our proposed classifications reflect our incomplete evidence and incomplete biological understanding, not a claim that the organism is partially sentient in proportion to our confidence.
This is also why the tool uses a sentience-plausibility gate followed by a separate affective-capacity analysis. The first asks whether there is sufficient reason to infer that anything can feel good or bad for the organism. The second asks, conditional on that, how differentiated and intense those states could be. The first is treated categorically in the underlying hypothesis but uncertain in our knowledge; the second is explicitly graded.
Thanks, Vasco — this is a very interesting challenge, and the pieces by Kammerer and Frankish are highly relevant.
I am not sure, however, that our use of sentience depends on the traditional conception of phenomenal consciousness that you are criticizing. In the Welfare Footprint Framework, the relevant question is whether an organism can have positive or negative affective states—states that can make its situation better or worse for it. We try to infer those states from converging behavioural, physiological, neural, pharmacological, cognitive, evolutionary, and ecological evidence.
This is why I would hesitate to focus only on what an organism can do. Behaviour and functional capacities are important evidence, but they are not themselves welfare. A biological or artificial system may avoid damage, learn, prioritize certain outcomes, and change its behaviour without anything necessarily feeling good or bad for it. The distinction between affective and non-affective control is therefore part of the question we are trying to investigate, rather than something we can simply set aside.
I would also hesitate to describe the empirical proxies as arbitrary. They are indirect and uncertain, and their interpretation depends partly on one’s theory of consciousness. But some proxies are clearly more informative than others. Their value can be assessed through causal and comparative evidence, experimental interventions, and whether different classes of indicators point toward the same conclusion.
That said, your comment suggests a useful improvement to the tool. We could define the sentience gate more carefully and make clearer that it is not trying to identify an ineffable property disconnected from observable biological processes.
The workflow itself would remain the same. First, we ask whether the available evidence supports the existence of any positive or negative affective states. Only then, conditional on that assessment, do we ask how intense those states could plausibly become. These are related but distinct questions: the sentience gate concerns whether there is any affective welfare subject at all, whereas the ceiling analysis concerns the upper limit of that subject’s affective range.
Some of the same evidence may inform both stages, but the inferential targets are different. We could make this distinction clearer in the article and in the tool, while also separating the observable evidence from the further inference about affective experience at each stage.
Someone sympathetic to Frankish’s view might interpret the same evidence without appealing to phenomenal properties as traditionally conceived. But for the WFF, we still need to distinguish systems that merely process information and regulate behaviour from organisms for which conditions can plausibly feel better or worse.
Thank you for drawing our attention to this. I think it may help us clarify both the article and the tool without changing the basic sequence of the analysis, and without requiring us to settle the broader philosophical debate before making practical progress.
Thanks, Jim! I think Dolores/Mildred is actually a very helpful toy example.
If both Dolores and Mildred already cross the threshold needed to lexically prioritize starvation, then Dolores’s stronger feeling may indeed add no extra functional value. That’s very close to the point we tried to make in the revised Figure 1 of Do primitive sentient organisms feel extreme pain?: two systems can differ in range while still being equally effective for prioritization, provided the relevant discriminative structure is the same.
So yes: in your setup, the extra intensity could be selectively neutral if it also carries no extra costs or constraints. That’s where the framework still bites. Our point isn’t that higher intensity must always be selected against, but that it shouldn’t automatically be treated as either necessary or neutral.
On your second point, I also agree that we should be careful: I would not want to claim, as a general rule, that “more intense” always means “more expensive.” The more modest claim is that some ways of implementing very high intensity may require broader integration, stronger modulation, or greater whole-system involvement, and if they do not, then your neutrality story remains a live possibility (even if it is not the default expectation in the framework).
This is also part of why we’ve been trying to make these distinctions more explicit in the more recent Interspecific Affect GPT post: not because it settles cases like this, but because it forces us to state more explicitly where the ceiling question depends on extra commitments, where neutrality remains a serious live possibility, and how this kind of reasoning can be pushed toward real taxa - something that matters directly for interspecific comparisons of the capacity to feel pain.
Update (April 2026)
Since writing this post, our thinking on this work has evolved in a few important ways.
In particular, what we originally referred to as the Pain Atlas Project is now better understood as part of a broader effort: the development of a Welfare Footprint Atlas. The goal is to enable the generation of structured, comparable, and inspectable estimates of animal welfare across products, production systems, and species.
The key shift is not simply the use of AI, but the ability to produce first-pass estimates at scale, making it easier to identify where suffering is concentrated and where interventions may have the greatest impact — while keeping assumptions explicit and open to revision.
We’ve updated the main text of the post to reflect this evolution, and we’re continuing to develop the underlying tools and methods that make this possible.
Thanks Vasco — that’s a reasonable concern, but I think it assumes a stronger claim than the framework is actually making.
We are not attempting to define a finely resolved ratio scale covering the entire possible range of pain intensities across taxa. The four intensities are intended as coarse phenomenological anchors, chosen as a practical balance between resolution and scientific tractability.
As we explain in a earlier paper:
So the goal is not to cover the entire theoretical intensity range with fine granularity, but to provide a small number of biologically interpretable categories that can be applied with reasonable consistency. Adding many more levels would only be an improvement if they could be assigned reliably; otherwise it would risk creating false precision.
And importantly, the framework is not committed to four categories as a final solution. If future work supports a better-validated scale with additional intermediate levels, those could be incorporated without difficulty. For now, four levels seem to provide a workable and defensible balance between usability and epistemic caution.
I recently came across this video clip where Michael Pollan argues that artificial systems cannot be conscious. His argument touches on several themes relevant to this post—specifically the conditions for the origin of sentience—but I believe it rests on a fundamental logical error.
Pollan’s core claim is that because feelings originate in the brainstem (a point that is scientifically sound) and are tied to biological vulnerability, they are inherently biological and cannot arise in artificial systems. His logic follows this structure:
This reasoning confuses evolutionary origin with functional requirement. Evolutionary history explains how a trait first appeared given the constraints of carbon-based nervous systems; it does not dictate the physical substrates capable of implementing that functional organization.
The "Feather Analogy" illustrates the flaw perfectly:
Clearly, the conclusion is false. If the brainstem's "feelings" are essentially the integration, valuation, and prioritization of internal states—all of which are computational processes—then the relevant question is whether that functional architecture can be implemented in non-biological substrates.
Pollan’s second argument—that sentience begins with "feelings" rather than "thoughts"—is again, backed by solid science. However, he then lapses into what I can only describe as a "word salad" regarding biological vulnerability. He claims feelings "have no weight" and require a mortal, sensible body. This ignores a crucial neurological fact: affective states do not require peripheral sensory input. For example:
These examples suggest that "feeling" is a representational state within a processing system. Crucially, we should not assume that affective states emerge only when there is a functional need for self-monitoring or goal-valuation. Instead, it is highly plausible that valence and sentience are emergent properties of the information-processing itself.
If a system architecture reaches a certain level of complexity and integration, the resulting "feelings" are ontologically real. To dismiss these states as "less real" because they lack a biological anchor or a "vulnerable body" is a category error; the reality of the experience is a property of the system's internal organization, not its hardware’s chemistry.
Bottom line: Pollan mistakes the "wetware" of our specific evolutionary path for the universal requirements of consciousness. From a welfare perspective, the possibility of sentience in digital minds remains a robust—and high-stakes—concern.