Skip to main content

Metaphor and Analogy



Many of our practices and much of our discourse in healthcare hinge on metaphor and analogy, whose significance is sometimes overlooked because they are considered merely decorative or escape notice altogether. Despite their relative neglect, they significantly shape our interpretations of what is happening as well as what should happen. This entry will examine metaphor before considering analogy, particularly analogical reasoning, noting their overlap where appropriate.

Metaphors in Bioethics

NATURE AND FUNCTION OF METAPHORS. Perhaps because medicine and healthcare involve fundamental matters of life and death for practically everyone, and in often mysterious ways, they are often described in metaphors. For instance, physicians may be viewed as playing God, or acting as parents, and nurses seen as advocates for patients, while medicine itself may be interpreted as warfare against disease. Metaphors involve imagining something as something else, for example, viewing human beings as wolves or life as a journey. "The essence of metaphor," according to George Lakoff and Mark Johnson, "is understanding and experiencing one thing through another" (p. 5). More precisely, metaphors are figurative expressions that interpret one thing in terms of something else (Soskice).

In contemporary philosophical literature on metaphor, critics have challenged some traditional conceptions, contending that metaphors are more than merely ornamental or affective ways to state what could be stated in a more literal or comparative way, and that they can be and often are cognitively significant (see, e.g., Black, 1962, 1979; Ricoeur; Soskice). According to the traditional substitution view, a metaphorical expression is merely a substitute for some equivalent literal expression. For example, the metaphorical expression "John is a fox" substitutes for the literal expression "John is sly and cunning." One common version of the substitution view, what philosopher Max Black (1962) calls a comparison view (elements of which can be found in Aristotle), construes metaphor as the presentation of an underlying analogy or similarity. Hence, metaphor is "a condensed or elliptical simile" (Black, 1962), or it is a "comparison statement with parts left out" (Miller). "John is a fox," for example, indicates that "John is like a fox in that he is sly and cunning." According to such views, metaphors are dispensable ways to express what could be expressed differently, but they often appeal to the emotions more effectively than their equivalent literal expressions or comparisons would do.

By contrast, many recent theories of metaphor stress its cognitive significance. In an early and very influential essay, Black (1962) defended an interaction view of metaphor, in which two juxtaposed thoughts interact to produce new meanings, through the metaphor's "system of associated commonplaces" or "associated implications." The metaphor—for instance, "wolf" in "man is a wolf"—serves as a "filter" for a set of associated implications that are transferred from the secondary subject (wolf) to the principal subject (man) in the sentence. In a full interaction or interanimation view of metaphor, the transfer of meaning occurs both ways, not merely from the secondary subject to the principal subject (Soskice).

Metaphors highlight and hide features of the principal subject, such as the physician who is viewed as a parent or as a friend, by their systematically related implications (Black, 1962; Lakoff and Johnson). When argument is conceived as warfare, for example, the metaphor highlights the conflict involved in argument, while it hides the cooperation and collaboration, involving shared rules, that are also indispensable to argument. Our metaphors thus shape how we think, what we experience, and what we do by what they highlight and obscure.

Metaphors are often associated with models. For instance, we have both metaphors and models of the doctor-patient relationship. The physician may be viewed through the metaphor of father and the patient through the metaphor of child, and their relationship may be interpreted through the model of paternalism. Models, for our purposes, state the network of associated commonplaces and implications in more systematic and comprehensive ways—according to Black, "every metaphor is the tip of a submerged model" (1979, p. 31).

Metaphors and models may be good or bad, living or dead. Both metaphors and models can be assessed by how well they illuminate what is going on and what should go on. We can distinguish descriptive and normative uses of metaphors and models, without admitting a sharp separation between fact and value. For instance, the metaphor of physician as father (or parent), and the model of paternalism (or parentalism), may accurately describe some relationships in medicine, or they may suggest ideal relationships in the light of some important principles and values.

MEDICINE AS WAR. The metaphor of warfare illuminates much of our conception of what is, and should be, done in healthcare. This metaphor emerges in the day-to-day language of medicine: The physician as the captain leads the battle against disease; orders a battery of tests; develops a plan of attack; calls on the armamentarium or arsenal of medicine; directs allied health personnel; treats aggressively; and expects compliance. Good patients are those who fight vigorously and refuse to give up. Victory is sought; defeat is feared. Sometimes there is even hope for a "magic bullet" or a "silver bullet." Only professionals who stand on the firing line or in the trenches can really appreciate the moral problems of medicine. And they frequently have "war stories" to relate. Medical organization, particularly in the hospital, resembles military hierarchy; and medical training, particularly with its long, sleepless shifts in residencies, approximates military training more than any other professional education in our society (Childress).

As medicine wages war against germs that invade the body and threaten its defenses, so the society itself may also declare war on cancer or on AIDS under the leadership of its chief medical officer, who in the United States is the surgeon general. Articles and books even herald the "Medical-Industrial Complex: Our National Defense." As Susan Sontag notes, "Where once it was the physician who waged bellum contra morbum, the war against disease, now it's the whole society" (p. 72).

The military metaphor first became prominent in the 1880s, when bacteria were identified as agents of disease that threaten the body and its defenses. The metaphor both illuminates and distorts healthcare. Its positive implications are widely recognized—for instance, in supporting a patient's courageous and hopeful struggle against illness and in galvanizing societal support to fight against disease. But the metaphor is also problematic. Sontag, who was diagnosed with cancer in the late 1970s, reports that her suffering was intensified by the dominance of the metaphor of warfare against cancer. Cancer cells do not just multiply; they are invasive. They colonize. The body's defenses are rarely strong enough. But since the body is under attack (invasion) by alien invaders, counterattack is justified. Treatments are also often described in military language:

Radiotherapy uses the metaphors of aerial warfare; patients are "bombarded" with toxic rays. And chemotherapy is chemical warfare, using poisons. Treatment aims to "kill" cancer cells (without, it is hoped, killing the patient). Unpleasant side effects of treatment are advertised, indeed overadvertised. ("The agony of chemotherapy" is a standard phrase.) It is impossible to avoid damaging or destroying healthy cells (indeed, some methods used to treat cancer can cause cancer), but it is thought that nearly any damage to the body is justified if it saves the patient's life. Often, of course, it doesn't work. (As in: "We had to destroy Ben Suc in order to save it.") There is everything but the body count. (Sontag, p. 65)

Such "military metaphors," Sontag suggests, "contribute to the stigmatizing of certain illnesses and, by extension, of those who are ill" (p. 99). Other ill individuals have found the military metaphor unsatisfactory for other reasons. For instance, as a teenager, Lawrence Pray originally tried to conquer his diabetes, but his struggles and battles were futile and even counterproductive. Then over time he came to view his diabetes not as an enemy to be conquered, but as a teacher. Only then did he find a personally satisfactory way of living (Pray and Evans).

Still others with illness, by contrast, have found the military metaphor to be empowering and enabling. In her wide-ranging study of pathographies, that is, autobiographical descriptions of personal experiences of illness, treatment, and dying, Anne Hunsaker Hawkins identifies several "metaphorical paradigms" that offer themes of "an archetypal, mythic nature." In addition to illness as a battle, she notes illness as a game or sport (a subset of the military metaphor), illness as a journey into a distant country, illness as rebirth or regeneration—and, on a somewhat different level, healthymindedness as an alternative to contemporary medicine. While pathographies are individualized statements, they provide "an immensely rich reservoir of the metaphors and models that surround illness in contemporary culture" (p.25). These various metaphorical paradigms structure individuals' interpretations of their experiences of illness. Patterns emerge in individuals' selection of metaphors. They vary in part according to the illness involved—for example, the military metaphor is more common in descriptions of experiences with cancer and AIDS, while the rebirth metaphor is more common in descriptions of a critical life-threatening event, such as a heart attack. Furthermore, the military metaphor is more prevalent than the journey metaphor because it better fits the experience of modern medicine—for instance, it is easier to construe the physician as a general in a war than as a guide on a journey. Nevertheless, these various metaphors are often mixed and complementary. They can be evaluated, Hawkins suggests, according to their capacity to enable and empower ill persons, for instance, by restoring a sense of personal dignity and worth. And, while expressing larger sociocultural patterns, the individual's choice of a particular metaphor is a creative act of assigning meaning to his or her illness.

The metaphor of warfare has been further challenged in modern medicine because of its apparent support for overtreatment, particularly of terminally ill patients, because death is the ultimate enemy, just as trauma, disease, or illness is the immediate enemy. Physicians and families under the spell of this metaphor frequently find it difficult to let patients die. Heroic actions, with the best available weapons, befit the military effort that must always be undertaken against the ultimate enemy. Death signals defeat and forgoing treatment signals surrender. Some clinicians even feel more comfortable withholding (i.e., not starting) a treatment for cancer, for instance, than they do withdrawing(i.e., stopping) the same treatment, in part because withdrawing treatment implies retreat.

According to its critics, the invocation of the military metaphor often fails to recognize moral constraints on waging war. "Modern medicine," William May writes, "has tended to interpret itself not only through the prism of war but through the medium of its modern practice, that is, unlimited, unconditional war," in contrast to the just-war tradition (1983, p. 66). In the spirit of modern total war, "hospitals and the physician-fighter wage unconditional battle against death" (1983, p. 66). One result is that many patients seek assisted suicide or active euthanasia in order to escape from this warfare's terrorist bombardment. Traditional moral limits in the conduct of war include the principle of discrimination, which authorizes direct attacks on combatants but not on noncombatants. In medical care, the opposing combatant is the disease or death, not the patient. However, the patient is regularly the battleground and sometimes even becomes the enemy. Furthermore, in accord with the just-war tradition's requirement of reasonable prospect of success and proportionality, the treatment should offer the patient a reasonable chance of success; his or her suffering must be balanced against the probable benefits of prolongation of life.

Other problematic or ambiguous implications of the war metaphor appear in the allocation of resources for and within healthcare. First, under the military metaphor, society's healthcare budget tends to be converted into a defense budget to prepare for and conduct war against disease, trauma, and death. As a consequence, the society may put more resources into healthcare in relation to other goods than it could justify, especially under a different metaphor, such as nursing or business (see below). Indeed, the society may overutilize healthcare, especially because technological care may contribute less to the national defense of health itself—through the reduction of morbidity and premature mortality—than other factors, such as the reduction of poverty.

Second, within the healthcare budget, the military metaphor tends to assign priority to critical care over preventive and chronic care. It tends to concentrate on critical interventions to cure disease, perhaps in part because it tends to view health as the absence of disease rather than a positive state. It tends to neglect care when cure is impossible. A third point is closely connected: In setting priorities for research and treatment, the military metaphor tends to assign priority to terminal diseases, such as cancer and AIDS, over chronic diseases. Fourth, medicine as war concentrates on technological interventions, such as intensive-care units, while downplaying less technological modes of care.

In short, the military metaphor has some negative or ambiguous implications for a moral approach to healthcare decisions: It tends to assign priority to healthcare (especially medical care) over other goods, and, within healthcare, to critical interventions over chronic care, killer diseases over disabling ones, technological interventions over care, and heroic treatment of dying patients rather than allowing them to die in peace.

Some of the negative or ambiguous implications of the war metaphor for healthcare can be avoided if, as noted earlier, the metaphor is interpreted in accord with the limits set by the just-war tradition. However, the war metaphor may require supplementation as well as limitation. It is not the only prominent metaphor for healthcare; since the early 1980s its dominance has been threatened by the language of economics and business, as reflected in the language of a healthcare industry. Providers deliver care to consumers, seek or are forced to seek productivity in light of costeffectiveness or cost-benefit analyses, and may be concerned with "resource management, managed-care systems, and market strategies" (Stein, p. 172). This metaphor also highlights and hides various features of contemporary healthcare. Many critics of this metaphor worry that the language of efficiency will replace the language of care and compassion for the sick and equity in distribution of healthcare. Nevertheless, this metaphor has become more and more pervasive and persuasive as the structure of medicine and healthcare has changed, and as concerns about costs have become more central in societal discussions. Patients often fear undertreatment as hospitals and professionals seek to reduce costs, in contrast to their earlier fears of overtreatment under the war metaphor.

Both military and economics metaphors illuminate contemporary healthcare. But they may not be adequate, even together, to guide and direct healthcare. Whether any particular metaphor is adequate or not will depend in part on the principles and values it highlights and hides. Others have proposed nursing, a subset of healthcare, as a supplementary metaphor for the whole of healthcare, because of its attention to caring more than curing and to hands-on rather than technological care. Even though this metaphor of nursing is also inadequate by itself, it could direct the society to alternative priorities in the allocation of resources for and within healthcare, particularly for chronic care.

THE WAR AGAINST AIDS. Even as the military metaphor has been partially displaced by business and economics metaphors in the changing structure of healthcare, it has gained favor as a way to describe and direct society's response to the major epidemic of the acquired immunodeficiency syndrome (AIDS). Societies often resort to the metaphor of war when a serious threat to a large number of human lives requires the mobilization of vast societal resources, especially when that threat comes from biological organisms, such as viruses, that invade the human body. And AIDS activists have appealed to the military metaphor in an effort to galvanize society and to marshal its resources for an effective counterattack against the human immunodeficiency virus (HIV) that causes AIDS. However, critics charge that the war on AIDS has diverted important resources away from other important wars, such as the war against cancer.

Other controversies have emerged. From the beginning of the war against AIDS, identification of the enemy has been a major goal. Once the virus was identified as the primary enemy, it also became possible to identify human beings who carry or harbor the virus. This technology then led to efforts to identify HIV-infected individuals, even through mandatory screening and testing, as potential enemies of the society. In social discourse and practice, the carrier tends to become an enemy as much as the virus he or she carries, especially since society views many actions that expose individuals to the risk of HIV infection as blameworthy. Thus, the metaphor of war often coexists with metaphors of AIDS as punishment and as otherness (Ross, 1989a, 1989b; Sontag). In this specific case of war against AIDS, just as in the general war against disease, the military metaphor would be less dangerous if society adhered to the constraints of the just-war tradition, rather than being tempted by a crusade.

RELATIONSHIPS BETWEEN HEALTHCARE PROFESSIONALS AND RECIPIENTS OF CARE. Relationships between physicians and other healthcare professionals, on one hand, and patients, on the other, have been described and directed by a wide variety of metaphors and models (Childress and Siegler). For example, William May (1983) has identified images of the physician as fighter, technician, parent, covenanter, and teacher; Robert Veatch has identified several major competing models of physician-patient relationships: engineering, priestly (which includes the paternalistic model), collegial, and contractual models. Other metaphors such as friend and captain of the ship have also been used (King et al.).

Some critics contend that such models are whimsical gestalts, that many other arbitrary models could be invented—for example, bus driver or back-seat driver—and that moral points can and should be made more directly (Clouser). Such criticisms overlook how metaphors and models function in the interpretation and evaluation of interactions between physicians and patients. They miss the role of imagination, which can be defined as "reasoning in metaphors" (Eerdman). For example, opponents of paternalistic medical relationships usually do not eschew all use of metaphor; instead they offer alternative metaphors, such as partnership or contracts. And these various metaphors may be more or less adequate to describe what occurs and to direct what should occur in health care.

Metaphors and models highlight and hide features of the roles of physicians and other healthcare professionals by their various associated implications. For example, viewing the physician as a parent—or specifically as a father, based on the nineteenth-century model of the family—highlights some features of medical relationships, such as care and control, while hiding others, such as the payment of fees. In their use to describe, interpret, and explain relationships, such metaphors are subject to criticism if they distort more than they illuminate. And when they are offered to guide relationships and actions, they are subject to criticism if they highlight only one moral consideration, such as the physician's duty to benefit the patient or to respect patient autonomy, while hiding or obscuring other relevant moral considerations. It is also appropriate to consider the feasibility of various ideal relationships in light of significant personal, professional, and institutional constraints.

Several metaphors may be necessary to interpret healthcare as it is currently structured and to guide and direct actions, practices, and policies in healthcare. Some metaphors may fit some relationships better than others; for example, relations in clinical research, family practice, and surgery may be illuminated respectively by the metaphors of partner, teacher-student, and technician-consumer. Furthermore, not all of these metaphors conflict with each other; some may even be mutually supportive as well as compatible, for example, contractor and technician.

NURSING AS ADVOCACY. Major changes in the conception of nursing correlate with alterations in its primary metaphors. Whether situated within the military effort against disease or viewed as physicians' handmaidens and servants, nurses have traditionally been expected to cultivate passive virtues, such as loyalty and obedience. Their moral responsibility was primarily directed toward physicians and institutions, such as hospitals, and only secondarily toward patients. This interpretation of responsibility was shaped in part by nursing's military origins in the nineteenth century, as well as by societal conceptions of gender (Winslow; Bernal). Then in the 1970s, nursing was reconceived through the metaphor of advocacy. Nurses became advocates for clients and consumers (the term patient was often rejected as too passive). This legal metaphor, drawn from the advocate as one who pleads another's cause, especially before a tribunal of justice, highlights active virtues such as courage, persistence, and perseverance, and views the nurse as primarily responsible to the patient or client. This metaphor is explicit or implicit in formal nursing codes, and it is also featured in a large number of nurses' stories of advocacy and conflict in healthcare (Winslow; Bernal).

Critics note that the metaphor of advocacy reduces the range of services traditionally offered by nurses; it is thus insufficiently comprehensive (Bernal). In addition to distorting the human experience of illness, it distorts nursing by focusing almost exclusively on patients' or clients' rights, construed mainly in terms of autonomy, and it neglects positive social relationships in healthcare (Bernal). It highlights conflict among healthcare professionals because it implies that some of them do not adequately protect the rights of patients. Thus, the metaphor frequently supports a call for increased nursing autonomy as a way to protect patient autonomy. Because of its adversarial nature, many question whether the metaphor of advocacy can adequately guide relationships among healthcare professionals in the long run, even if it is useful in the short run. The metaphor may also assume that the nurse's responsibility to the patient/client is always clear-cut and overriding, even though nurses may face serious conflicts of responsibility involving patients, other individuals, associates, and institutions (Winslow). At the very least, sympathetic commentators call for further clarification of the metaphor of advocacy (Winslow); while critics seek alternative metaphors and models, such as covenant (Bernal), partnership, teamwork, or collegiality, that appear to offer more inclusive, cooperative ideals.

PLAYING GOD AND OTHER METAPHORS OF LIMITS. "Playing God" has been a common metaphor for both describing and directing the activities of scientists, physicians, and other healthcare professionals. They have been criticized for usurping God's power—for instance, the power over life and death—by letting patients die or by using new reproductive technologies.

There are theological warrants for playing God in the Jewish and Christian traditions, which affirm the creation of human beings in God's image and likeness. Thus, Paul Ramsey calls on those who allocate healthcare to play God in a fitting way: We should emulate God's indiscriminate care by distributing scarce lifesaving medical technologies randomly or by a lottery rather than on the basis of judgments of social worth.

Despite a few such positive uses of the metaphor of "playing God," the metaphor is generally used to identify two aspects of divine activity that should not be imitated by humans: God's unlimited power to decide and unlimited power to act. On one hand, users of this metaphor demand scientific and medical accountability over unilateral decision making. On the other hand, critics call for respect for substantive limits—for example, not creating new forms of life (U.S. President's Commission, 1982).

Edmund Erde contends that statements such as "doctors should not play god" are so unclear that they cannot function as commands and do not articulate a principle; thus, they cannot be followed because agents do not know how to conform their actions to them. Nor do they explain why certain actions should not be undertaken. Such phrases are, Erde argues, "metaphoric in that they tuck powerful feelings and images into descriptive language that cannot be understood literally" (p. 606). Any activity, such as mercy killing, that is "labeled 'playing god' carries the implication that it is clearly wrong" (p. 607). These phrases are used for situations in which agents face choices, but one option is considered immoral and is rejected as arrogantly and presumptuously playing God. The background of intelligibility of this metaphor, according to Erde, is found in the Western idea of the great chain of being, which identifies appropriate responsibilities at each level and opposes the usurpation of power and the failure to respect limits.

Other important and widespread metaphors of limits include the "thin edge of the wedge" and the "slippery slope," both of which warn against undertaking certain actions because other unacceptable actions will inevitably follow. Examples regularly appear in debates about euthanasia. Even though such metaphors are often misused, they are appropriate in some contexts. In each use of these metaphors, important moral questions require attention—the evaluation of the first action and subsequent actions—and important conceptual and empirical questions must be addressed in order to determine whether the putatively bad consequences will inevitably follow what might be innocuous first steps. (Similar questions emerge for some analogies, such as the Nazi analogy, which is also widely invoked to oppose such practices as mercy killing.)

METAPHORS FOR BIOETHICS AND BIOETHICISTS. The role and function of the bioethicist have often been construed in metaphorical terms. The common language of applied ethics invokes the metaphor of engineering as an application of basic science that does not contribute to basic science. The expertise of applied ethicists resides in their ability to apply general theories and principles to specific arenas of human activity. The metaphor of application has been widely challenged on the grounds that it is too narrow and distorts much that is important in bioethics. The term applied suggests that ethicists are problem solvers rather than problem setters, that they solve puzzles rather than provide perspectives, that they answer rather than raise questions, and that they begin from theory rather than from lived experience. It implies a limited technical or mechanical model of ethics.

The term applied distorts the numerous theoretical controversies in bioethics, and neglects the way bioethics may help to resolve or recast some theoretical controversies. At the very least, the metaphor of application may need to be supplemented by various other metaphors for the task of practical ethics and the role of the practical ethicist: "Theoretician, diagnostician, educator, coach, conceptual policeman, and skeptic are also supplemental or alternative roles to that of the technician" (Caplan, p. 30).

Some other metaphors are drawn from ancient religious roles, such as prophet or scribe. Yet another metaphor is conversation, which is prominent in approaches to bioethics that emphasize interpretation, hermeneutics, and narrative. And the stranger has been proposed as the best metaphor for the ethicist in professional education because his or her outside perspective can challenge ordinary assumptions (Churchill).

Suggestions emerge at various times to retire all metaphors, not merely some metaphors in some realm of discourse—for instance, Sontag proposes retiring all metaphors for illness. However, it is not possible to strip our discourse in science, medicine, and healthcare, or in biomedical ethics, of all metaphors. Instead, we must use metaphors with care and must carefully assess their adequacy in descriptive and normative functions.

Analogies in Bioethics

ANALOGIES AND ANALOGICAL REASONING. Often metaphors and analogies are presented in ways that indicate their substantial overlap. Indeed, for the comparison view of metaphor, there is little difference between them, because metaphors are compressed analogies. Some recent theories of metaphor have stressed, by contrast, that metaphors create similarities rather than merely expressing previously established and recognized similarities or analogies. According to Black, comparison views of metaphor fail because they reduce the ground for shifts of meaning (from the secondary subject to the primary subject) to similarity or analogy(1962). Nevertheless, there is a strong consensus that metaphorical statements presuppose some resemblance, even when they also create resemblance (Ricoeur). Black later conceded that metaphors "mediate an analogy or structural correspondence." Metaphor is, roughly speaking, "an instrument for drawing implications grounded in perceived analogies of structure between two subjects belonging to different domains" (1979, p. 32). And yet metaphor does not merely compare two things that are similar, but rather enables us to see similarities in what would be regarded as dissimilar.

Metaphors and analogies are thus closely related, with metaphors both expressing and creating similarities. In general, good metaphors function cognitively to generate new meaning and insight, by providing new perspectives; while good analogies extend our knowledge by moving from the familiar to the unfamiliar, from the established to the novel. In stretching language and concepts for new situations, analogy does not involve the imaginative strain often evident in the use of metaphors (Soskice). Nevertheless, the differences in function between metaphors and analogies should not be exaggerated.

The term analogy derives from the Greek analogia, which referred to mathematical proportion. "An analogy in its original root meaning," Dorothy Emmet observes, "is a proportion, and primarily a mathematical ratio, e.g., 2: 4: : 4: X. In such a ratio, given knowledge of three terms, and the nature of the proportionate relation, the value of the fourth term can be determined. Thus analogy is the repetition of the same fundamental pattern in two different contexts" (p. 6).

Analogical reasoning proceeds inductively, moving from the known to the unknown. It appears prominently in problem solving and thus is featured in research in cognitive science and artificial intelligence (Helman; Keane). For instance, computer problem-solving programs must search for analogous problems that have been successfully solved to generate solutions to new problems whether in highly structured domains such as law or in less structured domains.

Analogical reasoning has an important place in moral discourse, not only because of its importance in problem solving, but also because of the widely recognized moral requirement to treat similar cases in a similar way. Often stated as a principle of universalizability or of formal justice or formal equality, dating back at least to Aristotle, the requirement to treat similar cases in a similar way also appears in the common law's doctrine of precedent. The basic idea is that one does not make an acceptable moral or a legal judgment—perhaps not even a moral or legal judgment at all—if one judges that X is wrong, but that a similar X is right, without adducing any relevant moral or legal difference between them. In general, analogical reasoning illuminates features of morally or legally problematic cases by appealing to relevantly similar cases that reflect a moral or legal consensus (precedent). Of course, much of the moral (or legal) debate hinges on determining which similarities and differences are both relevant and significant.

Since the early 1980s ethicists have directed new attention to the role of analogical reasoning in case-oriented or casuistical judgments in bioethics and elsewhere. In The Abuse of Casuistry, Albert Jonsen and Stephen Toulmin identify "the first feature of the casuistic method" in its classical formulations as "the ordering of cases under a principle by paradigm and analogy" (p. 252). For instance, the rule prohibiting killing is set out in paradigm cases that illustrate its most manifest breaches according to its most obvious meaning. Moving from simple and clear cases to complex and uncertain ones, casuists examine various alternative circumstances and motives to determine whether those other cases violate the rule against killing. They seek analogies that permit the comparison of "problematic new cases and circumstances with earlier exemplary ones," that is, the similar cases that constitute presumptions (Jonsen and Toulmin, p. 316).

Despite the claims of some modern casuists, it is not clear that analogical reasoning distinguishes casuistical from principlist approaches. For instance, in analyzing the novel microallocation problems of modern medicine, Paul Ramsey appealed to the analogous "lifeboat" cases—when some passengers have to be thrown overboard in order to prevent the lifeboat from sinking—as a way to interpret the requirements of the principle of equality of opportunity in distributing scarce lifesaving medical technologies such as kidney dialysis. Because principles and rules are indeterminate, and because they sometimes conflict, analogical reasoning can be expected in case judgments—mere application cannot be sufficient.

Analogies are often divided into two main types: analogies of attribution and analogies of proportion (Cahill). The analogy of attribution involves a comparison of two terms or analogates, both of which have a common property, the analogon, that appears primarily in one and secondarily in the other. As Thomas Aquinas noted, healthy is used primarily for a person in a state of health (a healthy person) and secondarily for those medicines and practices that help to maintain or restore health (e.g., a healthy diet) or specimens that provide evidence of the body's health (e.g., healthy blood). By contrast, in the analogy of proportion, the analogates lack a direct relationship, but each of them involves a relationship that can be compared to a relationship in the other (Cahill). This second type is most common in analogical reasoning in biomedical ethics, as is evident in debates about maternal-fetal relations and abortion, where analogies of attribution also appear, particularly with reference to the fetus.

Analogical reasoning in debates about maternal-fetal relations. Debates about maternal-fetal relations, including pregnant women's decisions to abort and to decline cesarean sections, illustrate the pervasiveness and importance of analogical reasoning. Traditionally, abortion has been construed as directly killing the fetus, an innocent human being, in violation of the duty of nonmaleficence. Hence, in traditional Roman Catholic moral theology, direct abortions are tantamount to homicide. Sometimes the analogy of the unjust aggressor appears in situations where the pregnancy threatens the pregnant woman's life or health; but it has not been accepted in official Catholic thought the way the similar analogy of the pursuer has been accepted in some Jewish thought to justify abortions when there is such a threat.

Some feminists and others have attempted to recast the debate about abortion to focus on the basis and extent of the pregnant woman's obligation to provide bodily life support to the fetus. Often accepting, at least for purposes of argument, the premise that the fetus is a human being from the moment of conception (or at some time during the pregnancy), they argue that this premise does not entail that the pregnant woman always has a duty to sustain the fetus's life regardless of the circumstances of pregnancy, the risks and inconveniences to the pregnant woman, and so forth. Their arguments often proceed through analogies to other hypothetical or real practices or cases, on the assumption that a judgment about those practices or cases will entail a similar judgment about abortion.

The fantastic abortion analogies introduced by Judith Jarvis Thomson (1971) have been particularly influential and controversial. In one of her artificial cases, an individual with a rare blood type is kidnapped by the Society of Music Lovers and attached to a famous violinist who needs to purify his system because of his renal failure. Part of the debate concerns whether relevant analogies can be found in such fantastic, artificial cases, in contrast to actual real-life cases. For example, against Thomson, John Noonan opposes abortion in part by appeal to a U.S. tort-law case, in which the court held liable the hosts who had invited a guest for dinner but then put him out of their house into the cold night even though he had become sick and fainted and requested permission to stay (Noonan).

Some feminists and others contend that other analogous real-life legal and moral cases support the pregnant woman's free decision to continue or to discontinue her pregnancy. For many the relevant analogous cases concern living organ and tissue donation. Such donations are conceived as voluntary, altruistic acts that should not be forced by others even to save the potential recipient's life. They are gifts of life. Requiring a pregnant woman to continue the pregnancy until birth imposes on her a heavier burden than others are expected to bear in analogous circumstances, such as a parent who could save a child's life by donating a kidney. Thus, the provision of bodily life support, whether through donating an organ or allowing the fetus to use the uterus, has been conceived as a gift of life that should not be legally enforced (Mattingly; Jung).

According to Lisa Sowle Cahill, much analogical reasoning about pregnancy overlooks what is unique about maternal-fetal relations and thus obscures the morally relevant features of pregnancy or makes some relevant features more significant than they are. Many analogies problematically narrow our moral perspective on abortion by portraying the inception of pregnancy as accidental and the fetus as strange, alien, and even hostile. Furthermore, they often rely on the connotative meanings of their terms, particularly as embedded in a story, such as Thomson's case of kidnapping the unwilling blood donor. Examples also appear in the rhetoric of abortion opponents who, for instance, speak of the fetus as a child, and thereby distort the unique dependence of the fetus on the pregnant woman (Cahill). Finally, Cahill contends, justifications of abortion based on analogy often rest on liberal convictions that special responsibilities derive only from free choice.

For all these reasons, Cahill holds that analogical reasoning needs supplementation through direct examination of the unique features of maternal-fetal relations, particularly total fetal dependence, and of the ways these unique features qualify maternal, professional, and societal obligations. She argues that, as a category or class of moral relations, pregnancy "is unique among human relations at least because in it one individual is totally and exclusively dependent on a particular other within a relation which represents in its physical and social aspects what is prima facie to be valued positively" (p. 283). Hence, she argues, most analogies hide what is distinctive and unique about pregnancy, even though they identify some morally relevant features of maternal-fetal relations.

With the emergence of other maternal-fetal conflicts, particularly regarding cesarean sections to benefit the fetus, similar debates have emerged about the appropriateness of the analogy with living organ and tissue donation. For instance, in the case of A.C. (1990), the majority of the court held that, just as courts do not compel people to donate organs or tissue to benefit others, so they should not compel cesarean sections against the will of pregnant women to benefit potentially viable fetuses. The dissenting opinion rejected the analogy with organ and tissue donation, insisting that the pregnant woman "has undertaken to bear another human being, and has carried an unborn child to viability," that the "unborn child's" dependence upon the mother is unique and singular, and that the "viable unborn child is literally captive within the mother's body"(A.C., In re,).

Even though analogies with organ and tissue donation are now widely invoked to oppose state control of pregnant women's decisions regarding both abortion and cesarean sections, there are important differences between these two contexts. In the abortion debate, pregnancy is viewed as the provision of bodily life support and is itself analogous to the donated organ. In the debate about cesarean sections, the surgical procedure is analogous to organ donation—the potentially viable fetus is removed for its own benefit rather than to benefit some other party as in organ or tissue donation. In the abortion debate, the pregnancy is viewed as invasive; in the debate about cesarean sections, the surgical procedure is invasive. The central issue is whether state coercion in these cases to benefit the fetus is morally and legally acceptable. The debate hinges in part on the appropriateness of the living organ and tissue donation as an analogy. Even the critics of the analogy engage in analogical reasoning, but they deny that the similarities are more morally or legally relevant and significant than the dissimilarities. Defenders of governmental coercion could also hold that the moral or legal precedent is mistaken and that organs and tissues should sometimes be conscripted or expropriated from living persons.

Similar disputes appear in other areas of contemporary bioethics—for instance, in debates about whether mandatory testing or screening for antibodies to the human immunodeficiency virus, which causes AIDS, can be justified by analogy to accepted practices of mandatory testing or screening; and in debates about whether transplantation experiments using human fetal tissue, following deliberate abortions, are analogous to the complicitous use of materials or data from the morally heinous Nazi experiments. In these cases, as in many others, the debates focus to a great extent on the relevance and significance of the proposed analogies.


Debates in biomedical ethics are often debates about which metaphors and analogies illuminate more than they distort. Far from being merely decorative or affective, metaphors and analogies are central to both discourse and practice. They must be evaluated specifically according to how well they function to describe and/or direct actions and relationships. Even though in recent bioethics metaphors and analogies have sometimes been offered as ways to circumvent or transcend principles and rules, particularly through attention to cases, narratives, and aesthetic dimensions of experience, they are not necessarily incompatible with principles and rules. Analogical reasoning is important within frameworks of principles and rules, as well as in casuistry, and metaphors and models often succeed or fail depending on how well they express the full range of relevant moral considerations.

james f. childress (1995)

SEE ALSO: Abortion; Cancer, Ethical Issues Related to Diagnosis and Treatment; Children: History of Childhood; Embryo and Fetus; Epidemics; Ethics; Holocaust; Literature and Medicine; Moral Status; Narrative; Responsibility; Value and Valuation; Women, Historical and Cross-Cultural Perspectives


A.C., In re. 1990. 57B A.2d 1235 (D.C. App.).

Bernal, Ellen W. 1992. "The Nurse as Patient Advocate." Hastings Center Report 22(4): 18–23.

Black, Max. 1962. "Metaphor." In Models and Metaphors: Studies in Language and Philosophy, pp. 25–47. Ithaca, NY: Cornell University Press.

Black, Max. 1979. "More About Metaphor." In Metaphor and Thought, pp. 19–43, ed. Andrew Ortony. Cambridge, Eng.: Cambridge University Press.

Cahill, Lisa Sowle. 1982. "Abortion and Argument by Analogy." Horizons 9(2): 271–287.

Caplan, Arthur L. 1980. "Ethical Engineers Need Not Apply: The State of Applied Ethics Today." Science, Technology, and Human Values 6(33): 24–32.

Childress, James F. 1982. Who Should Decide? Paternalism in Health Care. New York: Oxford University Press.

Childress, James F., and Siegler, Mark. 1984. "Metaphors and Models of Doctor-Patient Relationships: Their Implications for Autonomy." Theoretical Medicine 5(1): 17–30.

Churchill, Larry R. 1978. "The Ethicist in Professional Education." Hastings Center Report 8(6): 13–15.

Clouser, K. Danner. 1983. "Veatch, May, and Models: A Critical Review and a New View." In The Clinical Encounter: The Moral Fabric of the Patient-Physician Encounter, pp. 89–103, ed. Earl E. Shelp. Dordrecht, Netherlands: D. Reidel.

Eerdman, David V. 1969. "Coleridge as Editorial Writer." In Power and Consciousness, pp. 187–201, ed. Conor Cruise O'Brien and William Dean Vanech. New York: New York University Press.

Emmet, Dorothy Mary. 1945. The Nature of Metaphysical Thinking. New York: St. Martin's Press.

Erde, Edmund L. 1989. "Studies in the Explanation of Issues in Biomedical Ethics: II. On 'On Playing God,' etc." Journal of Medicine and Philosophy 14(6): 593–615.

Hawkins, Anne Hunsaker. 1993. Reconstructing Illness: Studies in Pathography. West Lafayette, IN: Purdue University Press.

Helman, David H., ed. 1988. Analogical Reasoning: Perspectives of Artificial Intelligence, Cognitive Science, and Philosophy. Dordrecht, Netherlands: Kluwer Academic Publishers.

Jonsen, Albert R., and Toulmin, Stephen. 1988. The Abuse of Casuistry: A History of Moral Reasoning. Berkeley: University of California Press.

Jung, Patricia Beattie. 1988. "Abortion and Organ Donation: Christian Reflections on Bodily Life Support." Journal of Religious Ethics 16(2): 273–305.

Keane, Mark T. 1988. Analogical Problem Solving. Chichester, England: Ellis Norwood.

King, Nancy M. P.; Churchill, Larry R.; and Cross, Alan W. 1988. The Physician as Captain of the Ship: A Critical Reappraisal. Dordrecht, Netherlands: D. Reidel.

Lakoff, George, and Johnson, Mark. 1980. Metaphors We Live By. Chicago: University of Chicago Press.

Mattingly, Susan S. 1984. "Viewing Abortion from the Perspective of Transplantation: The Ethics of the Gift of Life." Soundings 67(4): 399–410.

May, William F. 1975. "Code, Covenant, Contract, or Philanthropy." Hastings Center Report 5(6): 29–38.

May, William F. 1983. The Physician's Covenant: Images of the Healer in Medical Ethics. Philadelphia: Westminster Press.

Miller, George. 1979. "Images and Models, Similes and Metaphors." In Metaphor and Thought, pp. 202–250, ed. Andrew Ortony. Cambridge, Eng.: Cambridge University Press.

Noonan, John T. 1974. "How to Argue About Abortion." New York: Ad Hoc Committee in Defense of Life.

Pray, Lawrence, and Evans, Richard, III. 1983. Journey of a Diabetic. New York: Simon and Schuster.

Ramsey, Paul. 1970. The Patient as Person: Explorations in Medical Ethics. New Haven, CT: Yale University Press.

Ricoeur, Paul. 1977. The Rule of Metaphor: Multi-Disciplinary Studies of the Creation of Meaning in Language, tr. Robert Czerny. Toronto: University of Toronto Press.

Ross, Judith. 1989a. "Ethics and the Language of AIDS." In The Meaning of AIDS: Implications for Medical Science, Clinical Practice and Public Health Policy, pp. 30–41, ed. Eric T. Juengst and Barbara A. Koenig. New York: Praeger.

Ross, Judith. 1989b. "The Militarization of Disease: Do We Really Want a War on AIDS?" Soundings 72(1): 39–50.

Sontag, Susan. 1990. Illness as Metaphor; and, AIDS and Its Metaphors. New York: Doubleday Anchor Books.

Soskice, Janet Martin. 1985. Metaphor and Religious Language. Oxford: Clarendon Press.

Stein, Howard F. 1990. American Medicine as Culture. Boulder, CO: Westview Press.

Thomson, Judith Jarvis. 1971. "A Defense of Abortion." Philosophy and Public Affairs 1(1): 47–66.

U.S. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. 1983. Splicing Life. Washington, D.C.: U.S. Government Printing Office.

Veatch, Robert M. 1972. "Models for Ethics in Medicine in a Revolutionary Age." Hastings Center Report 2(3): 5–7.

Winslow, Gerald R. 1984. "From Loyalty to Advocacy: A New Metaphor for Nursing." Hastings Center Report 14(3): 32–40.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Metaphor and Analogy." Encyclopedia of Bioethics. . 22 Aug. 2019 <>.

"Metaphor and Analogy." Encyclopedia of Bioethics. . (August 22, 2019).

"Metaphor and Analogy." Encyclopedia of Bioethics. . Retrieved August 22, 2019 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.