I am opposed to animal experimentation. However, I do not for a moment deny that reasonable and well-meaning people can disagree about this issue. I am all for vigorous debate. But in order to be intelligent, the debate must employ terminology whose meaning is understood by all parties, including the audience or reader.

In the debate about animal experimentation, this is anything but the case. The two sides speak different languages. And that is not all. Those who defend animal experimentation tend to use everyday language in a technical way. This can be misleading. Indeed, sometimes the technical usage strains the everyday meaning to the breaking point.

I have dealt with this matter elsewhere regarding the terms “necessary,” “sacrifice,” and “welfare.” Here I will focus on what I consider to be the most flagrant instance of the phenomenon, namely, the use of the term “humane” by the biomedical research establishment and the laws that govern it.

The various laws and regulations that apply to animal experimentation, such as the federal Animal Welfare Act, mandate “humane” treatment, albeit without specifying what exactly that means. Even an explicit definition can, on reflection, prove empty of content – for example, this from the most recent edition of the National Research Council’s Guide for the Care and Use of Laboratory Animals: “Humane care means those actions taken to ensure that laboratory animals are treated according to high ethical and scientific standards.” Furthermore, it is common for experimenters and their publicists and defenders to assert that research on animals in biomedical laboratories is conducted humanely. I would be amazed to come across an acknowledgment by any one of them to the contrary.

Nor do I doubt the sincerity of their utterances. I fully accept that any reputable institution will only approve animal research that it believes has a real chance of advancing human knowledge about some important matter, such as a childhood disease, and when there is no nonanimal alternative. It is also clear that the laboratory staff cares for the animals as best they can, given the constraints of the research.

Many of the people who work in these laboratories sincerely love animals. Some of them are distressed themselves by the distress they are causing some of the animals in their charge. I think it is even plausible to view them as heroic in the sacrifice of their own emotional comfort to perform a task they consider regrettable but necessary.

But none of this alters the simple fact that, based on the everyday meaning of “humane,” the work that is done with animals in laboratories is inhumane. The typical animal lives his or her entire life in a cage, often in isolation from other animals. Many have been deliberately bred to suffer debilitating disease. Others are mutilated in surgical procedures.

Every year millions are subjected to pain or distress without recourse to anesthesia or analgesia, according to data interpreted by Larry Carbone, a clinical veterinarian and acting associate director of the Laboratory Animal Resource Center at University of California, San Francisco, in his authoritative book, What Animals Want: Expertise and Advocacy in Laboratory Animal Welfare Policy. The vast majority of the animals are killed, Carbone says. In light of the common conception of humane – characterized by tenderness, compassion, and sympathy – it would be downright Orwellian, it seems to me, to call this treatment humane.

And yet that is what is done. How can this be? The simple answer is that “humane” is implicitly defined as meeting accepted standards of care and use according to legal and institutional guidelines. What this means in practice is that anything can be done to a laboratory animal, provided it is necessary to carrying out an experiment or other procedure that a committee has deemed worthy on scientific and perhaps humanitarian grounds. (There is also veterinary research directed at the welfare of nonhuman animals, but even here the underlying purpose is not the welfare of the individual animal in the experiment.) I submit that this is an illegitimate use of the term “humane.”

It is certainly understandable that animal researchers would want to appropriate such a reassuring word to describe their work, for their own peace of mind as well as to garner approval from the public, granting agencies, legislators, and so forth. Furthermore, “humane” probably does accurately characterize the attitude of many attending staff, who strive to make the animals as happy or at least comfortable as possible under the circumstances. But in no way does this justify extension of the term to the institution of animal experimentation itself, nor to millions upon millions of intentional acts that are done in its service.

The question then is not whether the animals used in biomedical experimentation are treated humanely. Undeniably they are not, if we count lifelong confinement, premature killing, and cases of unrelieved pain and distress as inhumane. Rather, the question is whether the advance of medical science justifies the inhumane treatment of animals. By this common-sense clarification of language, I submit, animal experimentation could cease to seem acceptable to many who currently think it justified. But the larger point is that the resolution of the issue ought to be based on a clear understanding of the facts and not mere rhetoric.

Joel Marks is professor emeritus of philosophy at the University of New Haven and a scholar at Yale University’s Interdisciplinary Center for Bioethics.