How to Quantify Animal Suffering

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In my last post, I asked whether or not it’s presumptuous for animal advocates (who are most often human) to attempt to quantify suffering for different species and animals in diverse situations. It may seem reasonable to generalize that mammals are more capable of suffering than insects, for instance, although some people would argue the point. Getting more specific than that, like by suggesting that "battery hens" suffer more than shelter animals, would certainly generate more controversy. So, can we quantify animal suffering?


I would argue that there are only a handful of primary factors that are needed to estimate the amount of suffering caused by any particular use of animals. Those variables are:

    Number of Animals: This is the primary determinant of suffering, simply because more animals used for some human purpose also mean more suffering or abuse or neglect. Estimating the number of animals subjected to different conditions is relatively straightforward for most species. In the U.S., we have data on how many companion animals are euthanized, how many farm animals are slaughtered each year, etc. But we have comparatively little data on the number of animals used in experiments or decimated by habitat loss, as well as some other issues.

    Number of Days Spent Housed/Confined: We can fairly easily determine the number of years that the average dairy cow spends on the farm, for instance. Or we can measure the number of years the average chimpanzee spends in a research laboratory. Like estimating the number of animals, determining the time that animals spend being subjected to different conditions is an important factor in quantifying suffering. If more days are spent being confined to a cage, then presumably there is more suffering, all else equal.

    Housing/Confinement Conditions: This is where things start to get fuzzy and dangerously subjective. To compare the conditions of one animal to another requires a deeper understanding of animal suffering than humans currently have. For instance, we would need to establish a scale of animal suffering anchored by animals deemed to suffer the most versus those deemed to suffer the least. An interesting and maybe impossible question: do animals in the worst conditions suffer ten, a hundred, or a million times more than animals in the best conditions?

    Slaughter/Death Conditions: Many animals, such as those used for fur coats or pork chops, are bred and raised for the sole purposes of dying to fulfill some predetermined purpose. This is not true for all animals, of course, but eventually all animals used for human purposes will die, and not all deaths involve equal amounts of suffering. Again this would involve determining by what magnitude animals slaughtered in the most egregious conditions suffer more than animals who die naturally and/or without suffering.

There are of course other factors that are also important determinants of the pain or suffering caused by different uses of animals, but I would argue that these are the main ones. It boils down to how many animals are living and dying for various purposes, for how long, and under what conditions. I think it would be feasible to develop a model to estimate suffering for a broad and diverse set of animal issues based on these variables. That model would get complicated very fast, however, and as noted above, some of the factors are both highly subjective and also unverifiable. So the bigger question might be why we would want to develop such a model at all.

In attempting to answer my own question about the audacity of quantifying animal suffering, it occurs to me that doing so would be a largely pointless exercise. Any animal who suffers at human hands is of interest to animal advocates, and understandably so. While some people and organizations might be swayed to shift their priorities to different issues based on quantified suffering, most would probably not be. Animal advocacy is fundamentally an emotional issue for most people. But I guess there’s little room to complain as long as advocates are working hard to maximize the impact they’re having on the animal issues they choose to address.

Numerical estimates

Thanks for the great post! I am one of those (perhaps few) who do think that quantifying animal suffering to the best of our ability is highly important. To me, preventing two chickens from suffering is exactly twice as good as preventing one from suffering. When we treat animal advocacy as "fundamentally an emotional issue," it's the animals who are hurt by our failure to help as many of them as possible.

Your list of relevant factors is right on, and in fact, this page uses those considerations to come up with some numerical estimates of the relative suffering caused by various types of animal products. From the perspective of direct suffering on factory farms, getting someone to eat, say, a hamburger instead of chicken nuggets is 98% as good as getting them to eat a veggie burger. Of course, the picture isn't quite as clear when we consider other factors, e.g., environmental harm and human health.

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