I really appreciate you taking the time to write such a detailed reply to my comment, thank you! And for sharing additional reading material on these questions. What you say makes a lot of sense. I think this research is really important and fascinating work, and Iām excited to hear about what progress you can make.
I understand you might not have time to engage in further back-and-forth on this, but I just wanted to elaborate a bit on the one part of my comment that I think is maybe not directly answered by your reply. This is the issue around how we can compare the utility functions of different individuals, even in principle.
Suppose we know everything there is to know about how the brain of a fly works. We can figure out what they are thinking, and how these thoughts impact their behaviour. Maybe you are right that one day we might be able to infer from this that āfly experience Aā is roughly 10x more painful than āfly experience Bā (based purely on how it influences their choices among trade-offsāwithout relying on any assumptions around signal strength). But once we have determined the utility function for each separate individual (up to an undetermined constant factor), this still leaves open the problem of how to compare utility functions between different individuals, e.g. how to compare āfly experience Aā to āhuman experience Cā. The vN-M approach does not tell you how to do that.
With humans, you can fairly easily get around this limitation in practice. You just need to find one reference experience that you expect to be similar for everyone (which could be as simple as something like stubbing your toe) and then with that one bridge between individual utility functions established, a standard āunitā of utility, all other comparisons follow. I can even imagine doing something like this to compare the welfare of humans with other non-human mammals or birds.
But by the time we consider insects, I find it hard to imagine how we would approach picking this āreferenceā experience that will allow us to do the inter-species welfare comparisons that we want to do. Iām still not sure Iām convinced that the methods outlined here will ultimately enable us to do that. Itās not just that the āsignal strengthā assumption is āunprovenā, it is that I am struggling to wrap my head around what a proof of that assumption would even look like. The correlation between pain intensity and signal strength in vertebrates presumably is based on within-individual comparisons, not between-individual comparisons, and assuming that a correlation in the first-type of comparison implies a correlation in the other still seems like a big extrapolation to me.
Hi Toby, thank you for your kind words. I might take some time to answer, but Iām happy to continue this back-and-forth (and please feel free to challenge or push on any point you disagree with).
I believe the problem we face is practical in nature: we currently lack direct access to the affective states of animals, and our indirect methods become increasingly unreliable as we move further away from humans on the evolutionary tree. For instance, inferring the affective capacity of a reptile is challenging, let alone that of an arthropod or annelid. But when you mention the caveat āeven in principle,ā I feel much more optimistic. I do believe that, in principle, how affect varies can be projected onto a universal scaleāso universal that it could even compare affective experiences across sentient beings on other planets or in digital minds that have developed hedonic capacity.
Despite the variety of qualitative aspects (e.g., whether Pain stems from psychological or physical origins, or signals an unfulfilled need, a threat, damaged tissue, or a desire), the goodness or badness of a feelingāits āutilityāāshould be expressible along a single dimension of real numbers, with positive values for Pleasure, negative values for Pain, and zero as a neutral point. Researchers like Michael Mendl and Elizabeth Paul have explored similar ideas using dimensional models of affect, suggesting that valence and arousal might offer a way to compare experiences across species, which supports the idea of a universal scaleāthough they also note the empirical gaps we still face.
So, I see this challenge as a technical and scientific issue, not an epistemological one. In other words, Iām optimistic that one day weāll be able to say that a Pain value of, letās say, ā2.456, represents the same amount of suffering for a human, a fish, or a flyāprovided they have the neurological capacity to experience this range of intensities. I recognize this is a bold claim, and given the current lack of empirical data, itās highly speculativeāperhaps even philosophical. But this is my provisional opinion, open to change, of course! :)
I really appreciate you taking the time to write such a detailed reply to my comment, thank you! And for sharing additional reading material on these questions. What you say makes a lot of sense. I think this research is really important and fascinating work, and Iām excited to hear about what progress you can make.
I understand you might not have time to engage in further back-and-forth on this, but I just wanted to elaborate a bit on the one part of my comment that I think is maybe not directly answered by your reply. This is the issue around how we can compare the utility functions of different individuals, even in principle.
Suppose we know everything there is to know about how the brain of a fly works. We can figure out what they are thinking, and how these thoughts impact their behaviour. Maybe you are right that one day we might be able to infer from this that āfly experience Aā is roughly 10x more painful than āfly experience Bā (based purely on how it influences their choices among trade-offsāwithout relying on any assumptions around signal strength). But once we have determined the utility function for each separate individual (up to an undetermined constant factor), this still leaves open the problem of how to compare utility functions between different individuals, e.g. how to compare āfly experience Aā to āhuman experience Cā. The vN-M approach does not tell you how to do that.
With humans, you can fairly easily get around this limitation in practice. You just need to find one reference experience that you expect to be similar for everyone (which could be as simple as something like stubbing your toe) and then with that one bridge between individual utility functions established, a standard āunitā of utility, all other comparisons follow. I can even imagine doing something like this to compare the welfare of humans with other non-human mammals or birds.
But by the time we consider insects, I find it hard to imagine how we would approach picking this āreferenceā experience that will allow us to do the inter-species welfare comparisons that we want to do. Iām still not sure Iām convinced that the methods outlined here will ultimately enable us to do that. Itās not just that the āsignal strengthā assumption is āunprovenā, it is that I am struggling to wrap my head around what a proof of that assumption would even look like. The correlation between pain intensity and signal strength in vertebrates presumably is based on within-individual comparisons, not between-individual comparisons, and assuming that a correlation in the first-type of comparison implies a correlation in the other still seems like a big extrapolation to me.
Hi Toby, thank you for your kind words. I might take some time to answer, but Iām happy to continue this back-and-forth (and please feel free to challenge or push on any point you disagree with).
I believe the problem we face is practical in nature: we currently lack direct access to the affective states of animals, and our indirect methods become increasingly unreliable as we move further away from humans on the evolutionary tree. For instance, inferring the affective capacity of a reptile is challenging, let alone that of an arthropod or annelid. But when you mention the caveat āeven in principle,ā I feel much more optimistic. I do believe that, in principle, how affect varies can be projected onto a universal scaleāso universal that it could even compare affective experiences across sentient beings on other planets or in digital minds that have developed hedonic capacity.
Despite the variety of qualitative aspects (e.g., whether Pain stems from psychological or physical origins, or signals an unfulfilled need, a threat, damaged tissue, or a desire), the goodness or badness of a feelingāits āutilityāāshould be expressible along a single dimension of real numbers, with positive values for Pleasure, negative values for Pain, and zero as a neutral point. Researchers like Michael Mendl and Elizabeth Paul have explored similar ideas using dimensional models of affect, suggesting that valence and arousal might offer a way to compare experiences across species, which supports the idea of a universal scaleāthough they also note the empirical gaps we still face.
So, I see this challenge as a technical and scientific issue, not an epistemological one. In other words, Iām optimistic that one day weāll be able to say that a Pain value of, letās say, ā2.456, represents the same amount of suffering for a human, a fish, or a flyāprovided they have the neurological capacity to experience this range of intensities. I recognize this is a bold claim, and given the current lack of empirical data, itās highly speculativeāperhaps even philosophical. But this is my provisional opinion, open to change, of course! :)