1.

The news headlines on any given day in recent years, perhaps even on the same page, are likely to report a series of apparently unrelated events. What do phenomena such as the battle against a new resurgence of an epidemic, opposition to an extradition request for a foreign head of state accused of violating human rights, the strengthening of barriers in the fight against illegal immigration, and strategies for neutralizing the latest computer virus have in common? Nothing, as long as they are interpreted within their separate domains of medicine, law, social politics, and information technology. Things change, though, when news stories of this kind are read using the same interpretive category, one that is distinguished specifically by its capacity to cut across these distinct discourses, ushering them onto the same horizon of meaning. This category, as the title of this book makes apparent from the outset, is immunization. I will take a more detailed look at the semantic origins of this term and the mechanism by which it functions in the next section. But at a purely phenomenological level of discourse, a rough outline can immediately be traced out in an obvious analogy: in spite of their lexical diversity, all these events call on a protective response in the face of a risk. Whether we are talking about the outbreak of a new infectious disease, a dispute over established legal prerogatives, a sudden intensification of migratory flows, or an instance of tampering with large-scale communication systems—not to mention a terrorist attack—what is presented in any case is the rupture of a previous equilibrium and the consequent need for its reconstitution.

Up to this point, though, we are still dealing with a generic formulation of the category. It takes on a more nuanced connotation when we pass from mentioning vague situations of danger to identifying their specific characteristics. What becomes immediately obvious is that in each of the above examples the risk has to do with trespassing or violating borders. Whether the danger that lies in wait is a disease threatening the individual body, a violent intrusion into the body politic, or a deviant message entering the body electronic, what remains constant is the place where the threat is located, always on the border between the inside and the outside, between the self and other, the individual and the common. Someone or something penetrates a body—individual or collective—and alters it, transforms it, corrupts it. The term that best lends itself to representing this dynamic of dissolution—thanks precisely to the semantic polyvalence that places it at the crossroads of biology, law, politics, and communication—is “contagion”: what was healthy, secure, identical to itself, is now exposed to a form of contamination that risks its devastation. Naturally, a threat of this type is constitutionally inherent to every form of individual life, as it is to all forms of human aggregation. But what lends particular importance to the need for immunization, making it the symbolic and material linchpin around which our social systems rotate, is the accelerating, generalizing character that this contagious drift has taken on for some time now. When we count the number of people in Africa dying from AIDS as more than two million per year, with a forecasted mortality rate of one-quarter of the total population; or when we calculate that the potential number of immigrants to European countries from territories in the Third World, whose populations are growing at dizzying speeds, is in the tens of millions, we are only arriving at a macroscopic view of a phenomenon that is actually much more diffuse and articulated. What frightens us today is not contamination per se—which has been viewed as inevitable for some time now—as much as its uncontrolled and unstoppable diffusion throughout all the productive nerve centers of our lives.

2.

Take the apparently marginal case of the computer. The diffusion power of viruses transmitted by email is not only immeasurably faster than that of the viruses once introduced by floppy disk, but because it is practically coextensive with the space occupied by the Internet, it is also potentially unlimited. The instant the infected document is opened by the user, it is immediately multiplied through all the contacts in the user’s address book, who then go on in their turn to replicate it in an exponential fashion. If we consider that roughly a hundred new types of viruses are discovered each day, the enormous sums of money set aside by governments to come up with antivirus programs capable of stopping them becomes understandable (in the United States, four times as much as what is allocated for AIDS).

It might at first seem arbitrary to group this together with the legal controversy on the immunity of certain political figures, but the phenomenology is structurally analogous. The question needs to be framed in terms of the relationship between the law of an individual state—with all the ensuing prerogatives for the members of its government and diplomatic staff as well as for its members of parliament—and the law that is currently taking shape as a new form of international justice. Now, as holds true for all forms of boundary-breaking, it is clear that each time a judge puts forward an extradition request for a foreign subject who is protected by immunity, this creates a wound in the body of national sovereignty, one that is bound to be transmitted sooner or later to other organs of the state as well. This is what was really at stake in the legal battle against Pinochet’s immunity (against Milosevic’s as well, but for other reasons): not only his eventual conviction, but the contagious consequences that his conviction would give rise to in a world order based substantially on the mutual independence of sovereign states. Not surprisingly, Amnesty International hailed the sentence of the House of Lords and the later decision by the British Home Secretary Jack Straw, both condemning the ex-dictator, as the first breach to be opened in the heart of immunity law in favor of something that could be defined as “common law”: if it is true that a crime committed by any tyrant affects not only his or her own people but all the citizens of the world, then the implication is that the crime may be prosecuted by anyone, in any place. It implies that there exists an instance of justice that goes beyond the territorial borders of the law and law itself as a form of territorial delineation. Is this not the same concept of extranational justice that illegal immigrants or refugees stripped of their civil rights tacitly appeal to when they are expelled by the state police forces and taken back to the other side of the border that they violated?

What initially appeared as heterogeneous events begin to take on the shape of interdependent polarities of a single figure. If we consider the continual lexical slippage between one and the other as yet another effect of the contagion, affecting language itself, there can be no better confirmation. The multiple dimensions of the immigration phenomenon, spanning social, political, and legal realms, is familiar to us. But in addition to constituting a threat to the public order, immigration is also commonly presented by the media as a potential biological risk to the host country, according to a model that pathologizes the foreigner, the roots of which lie in the European imaginary of the last century. It is thus perfectly understandable that the type of terrorist attack most feared today, precisely because it is the least controllable, is a biological one: germs of smallpox, Ebola, even the plague, released into the air, the water, the food. The epidemic emergency that the major infectious diseases represent in their turn has precise economic, legal, political, and even military implications. A recent CIA report that envisages the possibility of revolutions, genocides, and the establishment of dictatorships as a consequence of demographic collapse in various parts of the Third World ranks AIDS in the top five out of seventy-five destabilizing factors on a planetary level. When we consider on the one hand the explicitly medical, even epidemiological, vocabulary adopted in the battle against computer viruses—also feared as a potential vehicle for international terrorism—and on the other hand the expressly military terminology used in the scientific world to describe how the immune system responds to environmental threats, we come full circle. The more life is hounded by a danger that circulates without distinction throughout all its practices, the more its response is concentrated into the mechanisms of a single device: as risk of the common becomes increasingly extensive, the response of the immune defense becomes increasingly intensive.

3.

But if the notion of immunity only takes form against the backdrop of meaning created by community, how are we to characterize their relationship? Is it a relation of simple opposition, or is it a more complex dialectic in which neither term is limited to negating the other but instead implicates the other, in subterranean ways, as its necessary presupposition? An etymological analysis goes some way to answering these questions. Latin dictionaries tell us that the noun immunitas, with its corresponding adjective immunis, is a negative or privative term whose meaning derives from what it negates or lacks, namely, the munus. The meaning of immunitas can be arrived at by examining the predominant meaning of its opposite: where munus refers to an office—a task, obligation, duty (also in the sense of a gift to be repaid)—by contrast, immunis refers to someone who performs no office (“e contrario immunis dicitur qui nullo fungitur officio”). Whoever is muneribus vacuus, sine muneribus, disencumbered, exonerated, exempted (think of the Latin term dispensatio) from the pensum of paying tributes or performing services for others, is defined as immune. Those who are immune owe nothing to anyone, in terms of both vacatio and excusatio: whether referring to an originary autonomy or the later release from a previously contracted debt, what counts in defining the concept is exemption from the obligation of the munus, be it personal, fiscal, or civil.

That said, our definitions up to this point are still too general to bring us any closer to answering the question with which we began. To do so, we must bring into view another vector of the concept that has remained in the shadows until now. Immunitas, as we have said, is an exemption. But, based on both ancient and modern definitions, it is also a privilege. The most fertile connotation of the term lies precisely where these two meanings overlap or intersect; immunity is perceived as such when it occurs as an exception to a rule that everybody else must follow: “immunis est qui vacat a muneribus, quae alii praestare debent.” The stress belongs on the second part of this sentence. In addition to being privative, immunity is also an essentially comparative concept: its semantic focus is more on difference from the condition of others than on the notion of exemption itself—so much so that the true antonym of immunitas may not be the absent munus, but rather the communitas of those who support it by being its bearers. In other words, if the privation—that which lacks—is the munus, the point of contrast against which immunity takes on meaning is the com through which the munus becomes generalized in the form of the communitas. This is also borne out by another even more pointed definition: “immunis dicitur, qui civitatis, seu societatis officia non praestat; qui vacat ab iis societatis officiis, quae omnibus communia sunt.” Compared to a generality of this sort, immunity is a condition of particularity: whether it refers to an individual or a collective, it is always “proper,” in the specific sense of “belonging to someone” and therefore “un-common” or “non-communal.” The official definition of ecclesiastical immunity in the canon law of the Roman Catholic Church expresses the same condition: “jus quo loca, res vel personae ecclesiasticae a communi onere seu obligatione liberae sunt et exemptae.” This is where its anti-social, or more precisely, anti-communal character comes to the fore: immunitas is not just a dispensation from an office or an exemption from a tribute, it is something that interrupts the social circuit of reciprocal gift-giving, which is what the earliest and most binding meaning of the term communitas referred to. If the members of the community are bound by the obligation to give back the munus that defines them as such, whoever is immune, by releasing him- or herself from the obligation, places himself or herself outside the community. In doing so, they become constitutionally “ungrateful”: “immunes ingratos significat, quemadmodum munificos dicebant eos qui grati et liberales exstitissent.”

4.

Although the most evident vector of meaning in the idea of immunity is expressed in its primal juxtaposition with community, this oppositional relation does not exhaust its significance. To fully understand the term, we must follow another semantic trajectory that does not entirely coincide with the first: rather, it intersects it as part of a complex figure. This second meaning originally derived from the biomedical aspect that little by little began to take its place alongside the legal one we have been discussing. From this point of view, what is meant by immunity is the refractoriness of an organism to the danger of contracting a contagious disease. In reality, even this definition is an ancient one, since an early instance is to be found in Lucan’s Pharsalia, referring to the resistance of an African tribe to snake poison. But what makes it significant for the purposes of our reconstruction is the turn it takes within its own field between the eighteenth and nineteenth centuries, first with the discovery of a measles vaccine by Jenner, and then with the experiments by Pasteur and Koch, the birth of medical bacteriology proper. The passage that most interests us is the one leading from natural to acquired immunity—in other words, from an essentially passive condition to one that is actively induced. The basic idea that came into play at a certain point was that an attenuated form of infection could protect against a more virulent form of the same type. From here came the deduction, proven by the effectiveness of the various vaccines, that the inoculation of nonlethal quantities of a virus stimulates the formation of antibodies that are able to neutralize pathogenic effects at an early stage.

In the following chapters we will be exploring this phenomenon in greater depth from a biological perspective; for now we will limit ourselves to a more general observation on the effects of meaning that it creates with regard to the immunitary paradigm as a whole. The first thing to point out is that the immunitary paradigm does not present itself in terms of action, but rather in terms of reaction—rather than a force, it is a repercussion, a counterforce, which hinders another force from coming into being. This means that the immunitary mechanism presupposes the existence of the ills it is meant to counter, not only in the sense that disease makes it necessary (it is the risk of infection that justifies the prophylactic measure) but also, in even stricter terms, that the immune mechanism functions precisely through the use of what it opposes. It reproduces in a controlled form exactly what it is meant to protect us from. The relationship between the protection and negation of life that is the subject of this book thus begins to take shape: life combats what negates it through immunitary protection, not a strategy of frontal opposition but of outflanking and neutralizing. Evil must be thwarted, but not by keeping it at a distance from one’s borders; rather, it is included inside them. The dialectical figure that thus emerges is that of exclusionary inclusion or exclusion by inclusion. The body defeats a poison not by expelling it outside the organism, but by making it somehow part of the body. As we were saying: the immunitary logic is based more on a non-negation, on the negation of a negation, than on an affirmation. The negative not only survives its cure, it constitutes the condition of effectiveness. It is as if it were doubled into two halves, one of which is required for the containment of the other: the lesser of two evils is intended to block the greater evil, but in the same language.

Of course, this homeopathic protection practice—which excludes by including and affirms by negating—does not consume itself without leaving traces on the constitution of its object: not only because of the compensatory mechanism of subtraction that thereby balances out the increase in life, but because this increase takes the form of a subtraction. Instead of something good being acquired, something bad has been taken away. Or better, it has been shifted, diverted, deferred. If life—which in all its forms is the object of immunization—cannot be preserved except by placing something inside it that subtly contradicts it, we must infer that the preservation of life corresponds with a form of restriction that somehow separates it from itself. Its salvation thus depends on a wound that cannot heal, because the wound is created by life itself. For life to remain as such, it must submit itself to an alien force that, if not entirely hostile, at least inhibits its development. It must incorporate a fragment of the nothingness that it seeks to prevent, simply by deferring it. This is where the structurally aporetic character of the immunitary process is to be located: unable to directly achieve its objective, it is forced to pursue it from the inside out. In so doing, it retains its objective in the horizon of meaning of its opposite: it can prolong life, but only by continuously giving it a taste of death.

5.

This antinomy, one might say, traverses all the languages of modernity, leading them to their outcome in dissolution. This book attempts to reconstruct the lexical shifts involved in this event, but also its deep genealogy, through a series of figures that, purely for the sake of explanatory convenience, we can trace back to different disciplines—law, theology, anthropology, politics, and biology—because, in point of fact, their tendency is to overlap. As we have said, this occurs along the clivage that at the same time juxtaposes and connects immunity and community, making one not only the contrasting background for the other, but also the object and content of the other. From this point of view, it is important not to lose sight of the fact that immunity, as a privative category, only takes on relief as a negative mode of community. Similarly, when viewed in a mirror image, community appears to be entirely immunized, attracted and swallowed up in the form of its opposite. Immunity, in short, is the internal limit which cuts across community, folding it back on itself in a form that is both constitutive and deprivative: immunity constitutes or reconstitutes community precisely by negating it.

This negative dialectic takes on particular prominence in the sphere of legal language or, to be more precise, in law as the immune apparatus of the entire social system. If, as Niklas Luhmann claims, starting in the eighteenth century, the semantics of immunity have progressively extended to all sectors of modern society, this means that the immune mechanism is no longer a function of law, but rather, law is a function of the immune mechanism. The German sociologist tends to present this crucial transition in its most neutral and, thus, most ideologically loaded wording, but in actuality it constitutes the point of precipitation of an otherwise sharply aporetic path that has its origin in the structural relation between law and violence. Far from being limited to the role performed by the law of immunizing the community from the violence that threatens it, violence actually comes to characterize the immunitary procedures themselves: instead of being eliminated, violence is incorporated into the apparatus it is intended to repress—once again, violently. This is the short circuit that Walter Benjamin recognizes in the ambivalent figure of Gewalt, understood as the inseparable intertwining of law and force. Held within this vise grip—to which Benjamin attributed the mythical traits of an unavoidable fate—every possible form of “right,” or “common” life, is sacrificed for the mere survival of its bare biological content.

The basic reason for such a reduction of life to simple living matter is traced by Simone Weil to the inherently private, and privative, nature of all law, including that which defines itself as public. Law, or right, in its historically constituted form, always belongs to someone, never to all. This is the source of its contrasting principle with the community which it is ordered to protect—but in a form that reverses its most intrinsic connotation: to be common, in the modern legal order, is only to lay claim to what is one’s own. Whence the necessary recourse to force, which constitutes both the transcendental precondition of law and the guarantee of its effectiveness. This is the conclusion, from another perspective, that René Girard also comes to in an analytical framework that places along the same genealogical track both the persecutory violence of the victimage mechanism and the legal type of repressive apparatus meant to secularize it, but which precisely for that reason also ends up reproducing it. That law is essential for protecting all types of shared life from the conflicts that traverse them does not detract from the core of violence that the law brings with it, lodged squarely at its origins but also at the very heart of its process. As was expressly stated in the ancient definition of the first nomos—which was sovereign over life and death—law is located at the point of indistinction between the preservation and exclusion of life. Life is preserved inside an order that excludes its free development because it is retained within the negative threshold defined by its opposite. The same claim of the law to provide for all acts that may contradict life, by penalizing them, places it in an anticipatory position, with the result that life is both protected and prejudged.

6.

This particular persistence of the negative in the form of its containment is the vector of meaning that in categorical terms connects the language of law with that of theology. I am not thinking especially, or exclusively, about the inevitably legal character that all religious dogmatics assume when passing from the phase of the prophetic word to its ecclesiastical codification, even though the significance of this phase, necessary to any religion wishing to endure over time, is a defensive self-immunization against the heretical tendencies threatening its stability. But what ties the form of the religio even more profoundly to the semantics of immunization is the overlap between the two prevailing vectors of meaning that are present from the time of its origins: one is salvific—in the biological sense of something that is healthy or keeps healthy—and the other is normative in character. The meaning created by their intersection is traceable to the idea that the survival of life, whether bodily or spiritual, depends on the performance of a ritual, but also on the observance of a prohibition, which must not be violated. This means that its unfolding, or its preservation, here at least, depends on submission to a foreign power that is not born of it, but which constitutes both its condition of existence and its intended outcome.

The simultaneous presence of development and restraint, opening and closing, positive and negative—typical of the immune paradigm—is represented in exemplary fashion by the enigmatic figure of the katechon: whoever its historical and political bearer may be, it still embodies the principle of defense from evil through its preliminary internalization. In biological terms it could be compared to the antibody that protects the Christian body through assimilation of the antigen. Or, in more legal terms, to the nomos that counters anomia, itself in an antinomic form, by taking on its language. Its most obvious scope of application, inasmuch as it refers to the legitimizing point of union between a plane of immanence and a plane of transcendence, is the category of “political theology.” Whether the plane of transcendence refers directly to God or to His earthly representative, one or the other is entrusted with the role of the unification of Christianity—which itself lies suspended between the religious sphere of the corpus mysticum and the secular although still theologically justified body politic. This is where the same terminology of corpus and “incorporation,” which early on took the place of carne and “incarnation,” mark the closure of the Christian vocabulary within an institutional framework intended to neutralize the anarchist and apocalyptic tensions that marked its beginnings. What soon emerged in response to these tensions was the normative reference to an order defined by divergence between the unfolding of existence and its ultimate meaning. Based on the assumption of this divergence, evil, inevitably at work throughout the course of history, can also be subsumed and overcome by its opposite. When this dialectic was later used—by the Christian community, it was originally intended to legitimize—in order to justify God, now personally accused of the evils of the world, the immunitary paradigm acquired the compensatory traits of a theodicy: no evil, no matter how intolerable its effects may appear, can cancel out the good that not only accompanies and compensates for it, but also, when viewed from a broader perspective, even ensues from it.

7.

It is not surprising that, as secularization has been established in the modern age, the category of compensatio has once again taken on central importance in the discipline known as “philosophical anthropology.” Starting out with an economic and legal meaning, the term gradually extended its reach first to the language of cosmology, then to psychoanalysis, until it acquired an even more general field of application: regardless of the sphere involved, compensation occurs when a lack—damage, a debt, a defect—is balanced by restoring the initial condition of equilibrium. But for this compensatory dynamic to take its place at the heart of the anthropological lexicon, a further conceptual shift was required to nudge it in an explicitly immunitary direction: namely, the passage of meaning from a simple equality between negative and positive to a positive functionalization of the negative. This is the route German philosophical anthropology took when it identified the original lack or insufficiency of human nature as man’s greatest resource. As Herder grasped, it is the failure of our organs to achieve the sort of specialization proper to other animal species that has put us in the position of having to artificially construct our experience in any environment we come to inhabit. This means that in order to preserve itself, human life must transcend itself—no longer in a sphere that is external to it, as theology would have it, but inside itself. It must objectify itself—and therefore exteriorize itself—in forms beyond its simple coming into being.

When Max Scheler recognizes the power of spirit as residing in its alterity with respect to the flow of life; when Helmuth Plessner searches for the intersection between power and survival in the human capacity to split ourselves off from the immediacy of our natural condition; when, finally, to an even more radical degree, Arnold Gehlen identifies the possibility of compensating for the morphological delay of animal-man in our exemption from instinctual excess, all three, in different ways, tie the preservation of life to the construction of an artificial order that distances life from itself. Whether this takes the form of a social ritual meant to safeguard the distance between individuals, as Plessner conceives it, or an institution able to stabilize otherwise destructive dynamics as in Gehlen, what remains is the anticommunal outcome that anthropological immunization seeks to prevent: the community as such is literally unsustainable. To allow the community to withstand the entropic risk that threatens it, and with which it ultimately coincides, it must be sterilized of its own relational contents. It must be immunized from the munus that exposes it to contagion using that which, coming from within it, goes beyond it. To this end are ordered the forms—roles, rules, institutions—by which anthropology divides life from its common content. What remains in common is nothing but mutual separation. This is where the intensely nihilistic aspect that philosophical anthropology absorbs from the immunitary dialectic is made explicit: the only protection against the nothingness underlying human nature is nothingness itself. And, indeed, a nothingness that is even more profound than the natural one because it is artificially created in view of its containment.

8.

But the excess of institutional mediation envisaged by philosophical anthropology is only one of two prevailing ways through which the immunitary paradigm relates to the collective dimension of life. There is another which must be added—or more often, which overlaps onto it—which seems to run in a symmetrically opposite direction. I am referring to the set of phenomena, or better, the regime of meaning, that at least since the appearance of Michel Foucault’s last work has come to be known as “biopolitics.” The contrast arises from the fact that while the anthropological model tends to separate life from itself by accentuating the formal elements, on the contrary, the biopolitical apparatus tends to eliminate any mediation. When politics takes life as an object of direct intervention, it ends up reducing it to a state of absolute immediacy. In this case, too, as in the previous one, any “form of life,” even the possibility of a “right life” or a “common life,” is excluded. Rather than deriving from an excess of form, though, its exclusion comes from life being crushed into its nude biological content. It is as if politics needed to deprive life of any qualitative dimension, to render it “only life,” “pure life,” or “bare life” in order to relate to it.

This is where the decisive importance attributed to the semantics of the body originates. Contrary to a widespread theory tying the immunitary dynamics of modernity to a procedure of gradual marginalization or emptying of the individual and social body, the biopolitical register is actually built around its renewed centrality. The body is the most immediate terrain of the relation between politics and life, because only in the body does life seem protected from what threatens to harm it and from its own tendency to go beyond itself, to become other than itself. It is as if life, to preserve itself as such, must be compressed and kept within the confines of the body. This is not because the body, both individual and collective, is not exposed to processes of involution and dissolution: what has more experience with the bite of evil than the body? Rather, it is because this risk is precisely what sets off the mechanisms of alarm, and therefore, of defense meant to protect it. It is true, then, as Foucault himself maintained, that the living being begins to enter onto the horizon of visibility of modern knowledge the moment its constitutive relationship with what continually threatens to extinguish it emerges. Sickness and death make up the cone of shadow within which the life sciences carve out their niche.

Biopolitics, one might say, simply takes this presupposition to its point of extreme radicality, where it is also productively turned inside out. By placing the body at the center of politics and the potential for disease at the center of the body, it makes sickness, on the one hand, the outer margin from which life must continually distance itself, and, on the other, the internal fold which dialectically brings it back to itself. The key figure in this passage is the classic one of the pharmakon, understood from the beginnings of the philosophical tradition in the double sense of medicine and poison, but in this context more specifically interpreted as an antidote needed to defend life from the dissolutive possibility of its being “put in common.” This immunitary significance is what lies behind the remarkable longevity of the “body politic” metaphor, not only in early modern treatises on governance where it appears in explicit form, but also subsequently, when the metaphor seems to eclipse itself simply because it is “realized” in the actual body of the people. In order for it to become an object of biopolitical practice, it had to be brought back to the same vocabulary of the “body politic” through which first the King and then the State had long been represented in the form of sovereign power. But this had to take place within a framework that inverts the relations of dominance between power and life. The threshold of transformation from the paradigm of sovereignty to that of biopolitics is to be located in the time when power was no longer the subject of inclusion (as well as of exclusion) of life but instead, life—its reproductive protection—became the ultimate criterion for legitimizing power. This explains the process of medicalization that has invested the entire gamut of social interaction over the last two centuries. It explains also, more generally, the hypertrophy of the security apparatuses that are increasingly widespread throughout contemporary societies. The blind spot that their development seems to arrive at can be seen precisely in this hypertrophy, since this self-protective syndrome ends up relegating all other interests to the background, including “interest” itself as a form of life-in-common; the effect it creates is actually the opposite of what is desired. Instead of adapting the protection to the actual level of risk, it tends to adapt the perception of risk to the growing need for protection—making protection itself one of the major risks.

9.

The relation between protection and negation also re-emerges out of this dynamic: life can be protected from what negates it only by means of a further negation. Even though this is the bottleneck our entire contemporary experience seems to funnel into, the intention of this book is not limited to describing it. Rather, I pose a fundamental question that puts its phenomenology into a more ambiguous light: is there a point at which the dialectical circuit between the protection and negation of life can be interrupted, or at least problematized? Can life be preserved in some other form than that of its negative protection? Naturally, I have tried from the outset to avoid the temptation of an immediately affirmative response, one that situates the development of life in a horizon that is radically external to the one defined by the paradigm of immunization. There are two reasons for this. First because, as I have stressed repeatedly, the category of immunity is inseparable from that of community: as its inverse mode, it cannot be eliminated. This is borne out by the fact that there is no community without some kind of immunitary apparatus. And second, because to negate the negation through which immunity in its turn negates what threatens life would mean to repeat the same procedure.

However, more recent study of the structure and functioning of the immune system seems to suggest another interpretive possibility, one that traces out a different philosophy of immunity. Without concealing its constitutive antinomy, even calling attention to it, this new interpretation situates immunity in a nonexcluding relation with its common opposite. The essential point of departure, recently adopted by such widely divergent thinkers as Donna Haraway and Alfred Tauber, is a conception of individual identity that is distinctly different from the closed, monolithic one we described earlier. It has been made possible, even inevitable, by advances in genetic and bionic technologies: rather than an immutable and definitive given, the body is understood as a functioning construct that is open to continuous exchange with its surrounding environment. Moreover—this is the argument (a problematic one, to be sure) put forward in the concluding section of this work—the immune system may very well be the driving force behind this exchange. Immune tolerance, understood as a product of immunity rather than as an unraveling or a deficiency of the system, is one of its first expressions. The figure of the implant, whether an artificial prosthesis or a natural implant like fertilized eggs in the mother’s womb, provides the most striking case in point. The fact that the genetic heterogeneity of the fetus rather than its genetic similarity is what encourages the mother’s immune system to accept it means that the immune system cannot be reduced to the simple function of rejecting all things foreign. If anything, the immune system must be interpreted as an internal resonance chamber, like the diaphragm through which difference, as such, engages and traverses us. As we were saying: once its negative power has been removed, the immune is not the enemy of the common, but rather something more complex that implicates and stimulates the common. The full significance of this necessity, but also its possibility, still eludes us.

*

We have spoken about how the concept of immunity is divided into two different lexical fields, one legal and political, and the other biomedical. This entire inquiry is directed toward probing the margin that simultaneously separates and joins these two categories. The question arises whether there are any historically contiguous segments in which these two meanings of immunity overlap in the same practice. I believe that one of the most significant cases, probably because it is the first, can be found in the right to immunity granted practicing physicians in Imperial Rome. The background and circumstances of this event are made hazy by the complex social position of Roman doctors. What immediately strikes the eye is an apparent inconsistency between the high level of income, but also power, that the medical profession attained versus the lack of consideration given to most of its members, except in rare cases, partly because of their humble origins. Based on statistics gathered from the inscriptions, the number of medici ingenui (free Roman citizens) is absolutely miniscule compared with medici servi, liberti (freed Roman slaves), or peregrini (immigrants from the provinces).¹ To this already perplexing set of circumstances—a real “social puzzle,” as it has been described²—the issue of immunity adds a further interpretive problem. How are we to explain and understand the granting of a particular privilege to a profession that often (in Pliny, for example) had derogative connotations associated with greed and even dishonesty? In reality, the granting of immunity was itself a far from peaceful process.³ To begin with, as we learn from Ulpian (Digest, 50.13.1.2–3), and especially from Modestino (Digest, 27.1.6.8–11), after Caesar had granted Roman citizenship to physicians practicing medicine in Rome starting in AD 46, the status of immunity granted to doctors by Vespasian, and then reaffirmed around AD 117 by Hadrian, involving exemption from certain civil and tax obligations, did not apply only to physicians but also to the other intellectual profession: philosophers, rhetoricians, and grammarians. Immunity was further tied to specific conditions, such as that of practicing in one’s hometown, and, of course, the probitas morum and the peritia artis. Despite these restrictions, as emerges from a text on a constitution by Commodus, immunitas was further limited by Hadrian’s son, Antoninus Pius, who fixed the number of doctors allowed to practice at five in small towns, seven in medium-sized towns, and ten in big cities (except Rome). All later attempts to pass measures extending these privileges were always accompanied by controversy and steps backward.⁴

Why so much vacillation on an issue that, all in all, was of such minor importance? Bowersock traces the cause back to some sort of incompatibility with the economic prosperity of the provinces where the exemption was in effect.⁵ But as Nutton points out, the question remains murky.⁶ How could a few privileges granted to no more than ten physicians put the economy of the entire province into crisis? I believe the answer should be sought elsewhere, or at least in other explanations as well: namely, in the ambiguous and vacillating status of immunity itself. An observation by Mario Vegetti points in the same direction when he stresses that immunitas “has a socially ambiguous meaning, because it excludes whoever enjoys it from the obligations that come with honores and munera, but also from the high prestige they confer.”⁷ Given that some of the exemptions included in immunity involved very important social munera civilia, like building and priestly functions or the protection of widows and orphans, in addition to the sordida munera, it becomes clear why the acquired privilege is negative, and thus, constitutively ambivalent: it consists in the privation of a munus, which, together with the weight of the onus, also includes the dignity of an officium that is prestigious because it participates in the public sphere. This privation is what explains the contradiction of a highly remunerative but socially unimportant position. It is no coincidence that the immunity granted to physicians falls under the purely private conception—in the sense of “being deprived of something”—of Roman medical practice. As Vegetti notes, this is precisely what differentiates the legally immunized doctors from those who were salaried state employees in Hellenistic times: while the salaried doctors had the obligation—the munus—to provide their services free of charge to all citizens and to the poor in particular, the private practitioners were exempt.⁸ Accordingly, they received potentially unlimited private honorariums but no public salary. Even in AD 386, under Valentinian II, when a college of fourteen public archiatri was set up, one per district, the members were paid in kind (commoda annonaria), to which they could add revenue from private sources, rather than being given a state salary. This explains the inherently equivocal status of Roman physicians: they were financially privileged, since there was no limit to how much they could charge for their services, yet socially disparaged. In other words, they were remunerated, but they were immune from the obligations and honors that were common to the rest of the free citizens.