A dilemma
To understand animal welfare and its scientific assessment, let us begin with a dilemma that threatened to throw animal welfare science into disarray.
In 1997 a scientific committee of the European Union reviewed the literature on the welfare of intensively kept pigs. The committee asked, among other questions, whether welfare problems are caused by housing sows in "gestation stalls" where the animals are unable to walk, socialize, or perform most other natural behaviour during the majority of pregnancy. The review concluded that, "Some serious welfare problems for sows persist even in the best stall-housing system", and with this review in hand the European Union passed a directive to ban the gestation stall as of 2013.
Not long after, a group of Australian scientists reviewed much the same literature and asked much the same question, but came up with essentially the opposite conclusion. They concluded that, "Both individual (i.e. stalls) and group housing can meet the welfare requirements of pigs." They also cautioned "public perceptions may result in difficulties with the concept of confinement housing" but that "the issue of public perception should not be confused with welfare". The swine industry in the United States has used that review, plus a similar one, to argue that there is no scientific basis for eliminating the gestation stall.
Very accomplished and capable scientists did both of these reviews with great thoroughness, and both groups likely felt that they had done the best and most objective job possible. What, then, went wrong? How could two groups of scientists review the same scientific literature and come up with opposite conclusions? If we can solve this dilemma, the solution will take us a long way toward understanding animal welfare and its scientific assessment.
Different views of animal welfare
To solve this problem, we need to go back to the debate that arose several decades ago when concerns were first expressed about the welfare of animals in the then-new confinement systems of animal production.
The first major criticism of confinement systems came in the book Animal Machines, by the English animal advocate Ruth Harrison. She described cages for laying hens and crates for veal calves, and she claimed that these systems are so unnatural that they cause animals to lead miserable and unhealthy lives. She went on to ask:
"How far have we the right to take our domination of the animal world? Have we the right to rob them of all pleasure in life simply to make more money more quickly out of their carcasses? A decade later, in Animal Liberation, Australian philosopher Peter Singer based his criticism of confinement production on the principle that actions should be judged right or wrong on the basis of the pain or pleasure that they cause.
In these and other quotations a key concern centred on words like "pleasure", "pain", "suffering", and "happiness". There is no simple English word to capture this class of concepts. They are sometimes called "feelings", but that term seems too insubstantial for states like pain and suffering. They are sometimes called "emotions", but emotions do not include states like hunger and thirst. Perhaps the most accurate, if rather technical, term is "affective states", a term that refers to emotions and other feelings that are experienced as pleasant or unpleasant rather than hedonically neutral.
Astrid Lindgren, the famous author of the Pippi Longstocking stories and a driving force behind animal welfare reform in Sweden, proposed:
"Let [farm animals] see the sun just once, get away from the murderous roar of the fans. Let them get to breathe fresh air for once, instead of manure gas."
And American philosopher Bernard Rollin insisted that we need:
"... a much increased concept of welfare. Not only will welfare mean control of pain and suffering, it will also entail nurturing and fulfilment of the animals' natures."
In these quotations, although affective states were often involved implicitly or explicitly, the central concern was for a degree of "naturalness" in the lives of animals: that animals should be able to perform their natural behaviour, that there should be natural elements in their environment, and that we should respect the "nature" of the animals themselves. All of the above quotations reflected the views of social critics and philosophers, but when farmers and veterinarians engaged in the debate, they brought a different focus.
Here the primary emphasis is on the fairly traditional concerns of veterinarians and animal producers that animals should have freedom from disease and injury, plus food, water, shelter and other necessities of life – concerns that we might sum up as the basic health and functioning of the animals.
In these various quotations, then, we see a variety of concerns that can be grouped roughly under three broad headings: one centres on the affective states of animals, one on the ability of animals to lead reasonably natural lives, and one emphasizes basic health and functioning. These are not, of course, completely separate or mutually exclusive; in fact, they often go hand in hand. Harrison and Lindgren clearly believed that allowing animals to live a more natural life would make them more happy and healthy; Sainsbury clearly believed that unhealthy animals would suffer.
Nonetheless, the different areas of emphasis are sufficiently independent that the pursuit of any one does not necessarily improve animal welfare as judged by the other criteria. Fifty years ago the American psychologist Harry Harlow wanted to create a colony of disease-free monkeys for research purposes. To do this Harlow separated infant rhesus macaques from their mothers a few hours after birth, and raised them in individual cages where they could be isolated from pathogens. The monkeys could see and hear each other but they had no physical contact. The method produced monkeys with excellent physical health, but as the animals matured Harlow realized that they were, in his words, "emotionally disturbed"
What if we pursue only naturalness? Various studies of outdoor rearing systems show that animals may have plenty of fresh air and freedom to perform their natural behaviour, but may also be challenged by parasites, predators, and harsh weather that could be better controlled in more artificial conditions. Examples of problems include high neonatal mortality in outdoor pig units , and high levels of parasitism among chickens on organic farms.
Much the same is true of the pursuit of happiness. Well-fed Labrador Retrievers may never suffer from hunger but are likely to develop heart problems from being over-weight, and human smokers may feel miserable when they try to stop smoking even though they accept that this painful process is good for their health.
Given this complexity, we are left with a conception of animal welfare shown in Figure 1 which provides a summary of three key points: that animal welfare involves different components that can be grouped roughly under three headings; that these involve considerable but imperfect overlap; and that the pursuit of any one criterion does not guarantee a high level of welfare as judged by the others.
