Heather Browning

‘Sentience’ sometimes refers to the capacity for any type of subjective experience, and sometimes to the capacity to have subjective experiences with a positive or negative valence, such as pain or pleasure. We review recent controversies regarding sentience in fish and invertebrates and consider the deep methodological challenge posed by these cases. We then present two ways of responding to the challenge. In a policy-making context, precautionary thinking can help us treat animals appropriately despite continuing uncertainty about their sentience. In a scientific context, we can draw inspiration from the science of human consciousness to disentangle conscious and unconscious perception (especially vision) in animals. Developing better ways to disentangle conscious and unconscious affect is a key priority for future research.

One of the biggest problems in applications of animal welfare science is our ability to make comparisons between different individuals, particularly different species. Although welfare science provides methods for measuring the welfare of individual animals, there’s no established method for comparing measures between individuals. This problem occurs because of the underdetermination of the conclusions given the data, arising from two sources of variation that we cannot distinguish – variation in the underlying target variable (welfare experience) and in the relationship of measured indicators to the target. In this paper I describe the similarity assumptions that underlie our current applications of interspecies comparisons and examine in which cases they are justified, as well as describing alternative methods we may use when they are not. In the end, all our available options for making interspecies comparisons are imperfect, and we need to make explicit context-specific decisions about which will be best for the task at hand while acknowledging their potential limitations. Future developments in our understanding of the biology of sentience will help strengthen our methods of making welfare comparisons.

In modern zoos, enrichment programs have become a standard part of animal care routines. Although 'higher' primates usually receive complex enrichment programs, encompassing many types of enrichment, these are less common for prosimians. These animals often largely receive food-based enrichment, as was previously the case at Auckland Zoo, where the ring-tailed lemur enrichment schedule contained only three different items, all food-related. Lemurs tend to be considered less curious and quick to learn than other primates, as well as being less manually dextrous, and for these reasons can be overlooked for complex enrichment. However, they have strong sensory abilities, in particular an acute sense of smell (Sauther et al 1999). This paper describes an enrichment program designed for the lemurs at Auckland Zoo with the aim of stimulating all senses.

Sentience is the capacity to have feelings, such as feelings of pain, pleasure, hunger, thirst, warmth, joy, comfort and excitement. It is not simply the capacity to feel pain, but feelings of pain, distress or harm, broadly understood, have a special significance for animal welfare law. Drawing on over 300 scientific studies, we evaluate the evidence of sentience in two groups of invertebrate animals: the cephalopod molluscs or, for short, cephalopods (including octopods, squid and cuttlefish) and the decapod crustaceans or, for short, decapods (including crabs, lobsters and crayfish). We also evaluate the potential welfare implications of current commercial practices involving these animals.

The performance of natural behavior is commonly used as a criterion in the determination of animal welfare. This is still true, despite many authors having demonstrated that it is not a necessary component of welfare –some natural behaviors may decrease welfare, while some unnatural behaviors increase it. Here I analyze why this idea persists, and what effects it may have. I argue that the disagreement underlying this debate on natural behavior is not one about which conditions affect welfare, but a deeper conceptual disagreement about what the state of welfare actually consists of. Those advocating natural behavior typically take a “teleological” view of welfare, in which naturalness is fundamental to welfare, while opponents to the criterion usually take a “subjective” welfare concept, in which welfare consists of the subjective experience of life by the animal. I argue that as natural functioning is neither necessary nor sufficient for understanding welfare, we should move away from the natural behavior criterion to an alternative such as behavioral preferences or enjoyment. This will have effects in the way we understand and measure welfare, and particularly in how we provide for the welfare of animals in a captive setting.

The keeping of captive animals in zoos and aquariums has long been controversial. Many take freedom to be a crucial part of animal welfare and, on these grounds, criticise all forms of animal captivity as harmful to animal welfare, regardless of their provisions. Here, we analyse what it might mean for freedom to matter to welfare, distinguishing between the role of freedom as an intrinsic good, valued for its own sake and an instrumental good, its value arising from the increased ability to provide other important resources. Too often, this debate is conducted through trading intuitions about what matters for animals. We argue for the need for the collection of comparative welfare data about wild and captive animals in order to settle the issue. Discovering more about the links between freedom and animal welfare will then allow for more empirically informed ethical decisions regarding captive animals.

This paper addresses what we consider to be the most pressing challenge for the emerging science of consciousness: the measurement problem of consciousness. That is, by what methods can we determine the presence of and properties of consciousness? Most methods are currently developed through evaluation of the presence of consciousness in humans and here we argue that there are particular problems in application of these methods to nonhuman cases—what we call the indicator validity problem and the extrapolation problem. The first is a problem with the application of indicators developed using the differences between conscious and unconscious processing in humans to the identification of other conscious vs. nonconscious organisms or systems. The second is a problem in extrapolating any indicators developed in humans or other organisms to artificial systems. However, while pressing ethical concerns add urgency to the attribution of consciousness and its attendant moral status to nonhuman animals and intelligent machines, we cannot wait for certainty and we advocate the use of a precautionary principle to avoid causing unintentional harm. We also intend that the considerations and limitations discussed in this paper can be used to further analyze and refine the methods of consciousness science with the hope that one day we may be able to solve the measurement problem of consciousness.

In this essay, we discuss Simona Ginsburg and Eva Jablonka’s The Evolution of the Sensitive Soul from an interdisciplinary perspective. Constituting perhaps the longest treatise on the evolution of consciousness, Ginsburg and Jablonka unite their expertise in neuroscience and biology to develop a beautifully Darwinian account of the dawning of subjective experience. Though it would be impossible to cover all its content in a short book review, here we provide a critical evaluation of their two key ideas—the role of Unlimited Associative Learning in the evolution of, and detection of, consciousness and a metaphysical claim about consciousness as a mode of being—in a manner that will hopefully overcome some of the initial resistance of potential readers to tackle a book of this length.

Animal welfare has a long history of disregard. While in recent decades the study of animal welfare has become a scientific discipline of its own, the difficulty of measuring animal welfare can still be vastly underestimated. There are three primary theories, or perspectives, on animal welfare - biological functioning, natural living and affective state. These come with their own diverse methods of measurement, each providing a limited perspective on an aspect of welfare. This paper describes a perspectival pluralist account of animal welfare, in which all three theoretical perspectives and their multiple measures are necessary to understand this complex phenomenon and provide a full picture of animal welfare. This in turn will offer us a better understanding of perspectivism and pluralism itself.

Animal welfare is a concept that plays a role within both our moral deliberations and the relevant areas of science. The study of animal welfare has impacts on decisions made by legislators, producers and consumers with regards to housing and treatment of animals. Our ethical deliberations in these domains need to consider our impact on animals, and the study of animal welfare provides the information that allows us to make informed decisions. This thesis focusses on taking a philosophical perspective to answer the question of how we can measure the welfare of animals. Animal welfare science is an applied area of biology, aimed at measuring animal welfare. Although philosophy of animal ethics is common, philosophy focussing on animal welfare science is rare. Despite this lack, there are definitely many ways in which philosophical methods can be used to analyse the methodologies and concepts used in this science. One of the aims of the work in this thesis is to remedy this lack of attention in animal welfare. Animal welfare science is a strong emerging discipline, but there is the need for conceptual and methodological clarity and sophistication in this science if it is to play the relevant informative role for our practical and ethical decision-making. There is thus is a strong role here for philosophical analysis for this purpose. The central aim of this thesis is to provide an account of how we can measure subjective animal welfare, addressing some of the potential problems that may arise in this particular scientific endeavour. The two questions I will be answering are: what is animal welfare, and how do we measure it? Part One of the thesis looks at the subjective concept of animal welfare and its applications. In it, I argue for a subjective welfare view - that animal welfare should be understood as the subjective experience of individuals over their lifetimes - and look at how the subjective welfare concept informs our ethical decision-making in two different cases in applied animal ethics. Part Two of the thesis looks more closely at the scientific role of welfare. Understanding welfare subjectively creates unique measurement problems, due to the necessarily private nature of mental states and here I address a few of these problems, including whether subjective experience is measurable, how we might validate indicators of hidden target variables such as welfare, how we can make welfare comparisons between individual animals and how we might compare or integrate the different types of experience that make up welfare. I end with a discussion of the implications of all these problems and solutions for the practice of welfare science, and indicate useful future directions for research.

When making decisions about action to improve animal lives, it is important that we have accurate estimates of how much animals are suffering under different conditions. The current frameworks for making comparative estimates of suffering all fall along the lines of multiplying numbers of animals used by length of life and amount of suffering experienced. However, the numbers used to quantify suffering are usually generated through unreliable and subjective processes which make them unlikely to be correct. In this paper, I look at how we might apply principled methods from animal welfare science to arrive at more accurate scores, which will then help us in making the best decisions for animals. I argue that a combined use of both a whole-animal measure and a combination measurement framework for assessing welfare will give us the most accurate answers to guide our action.

The performance of natural behavior is commonly used as a criterion in the determination of animal welfare. This is still true, despite many authors having demonstrated that it is not a necessary component of welfare – some natural behaviors may decrease welfare, while some unnatural behaviors increase it. Here I analyze why this idea persists, and what effects it may have. I argue that the disagreement underlying this debate on natural behavior is not one about which conditions affect welfare, but a deeper conceptual disagreement about what the state of welfare actually consists of. Those advocating natural behavior typically take a “teleological” view of welfare, in which naturalness is fundamental to welfare, while opponents to the criterion usually take a “subjective” welfare concept, in which welfare consists of the subjective experience of life by the animal. I argue that as natural functioning is neither necessary nor sufficient for understanding welfare, we should move away from the natural behavior criterion to an alternative such as behavioral preferences or enjoyment. This will have effects in the way we understand and measure welfare, and particularly in how we provide for the welfare of animals in a captive setting.

What is it like to be a bat? What is it like to be sick? These two questions are much closer to one another than has hitherto been acknowledged. Indeed, both raise a number of related, albeit very complex, philosophical problems. In recent years, the phenomenology of health and disease has become a major topic in bioethics and the philosophy of medicine, owing much to the work of Havi Carel (2007, 2011, 2018). Surprisingly little attention, however, has been given to the phenomenology of animal health and suffering. This omission shall be remedied here, laying the groundwork for the phenomenological evaluation of animal health and suffering.

One of the biggest ethical issues in animal agriculture is that of the welfare of animals at the end of their lives, during the process of slaughter. Much work in animal welfare science is focussed on finding humane ways to transport and slaughter animals, to minimise the harm done during this process. In this paper, we take a philosophical look at what it means to perform slaughter humanely, beyond simply reducing pain and suffering during the slaughter process. In particular, we will examine the issue of the harms of deprivation inflicted in ending life prematurely, as well as shape of life concerns and the ethical implications of inflicting these harms at the end of life, without the potential for future offsetting through positive experiences. We will argue that though these considerations may mean that no slaughter is in a deep sense truly ‘humane’, this should not undermine the importance of further research and development to ensure that while the practice continues, animal welfare harms are minimised as far as possible.