The age of great power rivalry and competition is back. We now recognize, as clearly stated in the 2017 National Security Strategy, that the United States faces competitors and rivals, and that the world is not on an inevitable path toward harmony. To be even more blunt, the United States has enemies of different stripes and along a long frontier, and the coming decades will demand a lot from American citizens and U.S. allies if they want to maintain the political equilibrium that underwrites their liberty.

The existence of enemies should not be cause for despair, however. To start with, their presence is not an anomaly but a constant throughout history; enemies and rivals will never disappear. The defeat of one enemy is likely to give rise to another, of different type and power but no less dangerous. Social interactions inevitably generate friction and rivalries; blissful isolation invites envy; and friendships and alliances are both a response to, and a source of, enmity. Regardless of how hard we try to live in harmonious relations with others, enemies are an inescapable and enduring reality of political life.

The question is what should we do about them. Compete with them and defeat them—yes, of course. But even before doing that, perhaps we can benefit from them. This is, in a nutshell, what Plutarch suggests in a short essay entitled “How to Profit by One’s Enemies.”¹

Probably an extempore oration that Plutarch later wrote down, its main focus is on self-improvement, on the individual’s path toward a virtuous life. It is neither a treatise of strategy nor a letter of advice to a statesman, and it does not address questions of national security or geopolitical rivalry. Nonetheless, it is about social relations and consequently it has some applicability to the wider realm of political interactions, including those among states. The ancients did not separate neatly the various levels of human action, from the individual to the polity, allowing therefore an easy transfer of lessons from the life of a man to the life of a city. States are not “black boxes” that act in ways that are fundamentally different from those of individual human beings. Therefore, the dynamics that characterize interpersonal relations (for example, friendships and enmities) are akin to those that shape strategic interactions among polities (for example, alliances and geopolitical rivalries).

Plutarch begins by recognizing that enemies will always exist for two related reasons. First, rivalries arise because of the acquisitive impulse of men, which spurs us to desire what we do not possess, leading to a clash with others. It is thus naive to expect that enmities can wither away and the harmony of friendship can spread throughout the world. Plutarch notes that a “government which has not had to bear with envy or jealous rivalry or contention—emotions most productive of enmity—has not hitherto existed.”²

The second reason for the continuing presence of enemies is the praiseworthy and necessary search for friends. “For our very friendships, if nothing else, involve us in enmities.”³ To have friends is ipso facto to have enemies. A slight suggestion is present here of the risk of entrapment, namely, of the danger of becoming involved in squabbles of friends or allies in which we have less interest than they do. In other words, the enemy of our ally is not necessarily our enemy—or at least, it should not be. A logical consequence of this reasoning is that friendships or alliances are risky propositions because they create enemies that we may not have had beforehand. Plutarch’s point, however, is that as enemies are always present so is the necessity of friends. We seek allies to balance against existing rivals but also to improve our welfare (and thus we would seek them even in the absence of enemies). Asking whether friendships create new enemies is fruitless. Enemies and allies will continue to exist because of the eternal competition in social interactions at every level. (As Evelyn Waugh put it: “It’s going to be a long war. The great thing is to spend it among friends.”)

The question then becomes whether we can turn this tragic reality—the presence of enemies—into an opportunity. It is obvious that enemies are dangerous because they seek to damage us in some way, and consequently life would be easier without them. But a sign of the intelligence proper to wise individuals is the ability to figure out how to benefit from otherwise undesirable situations. “Fools spoil even their friendships,” Plutarch writes, “while wise men are able to make a fitting use even of their enemies.”⁴

Plutarch suggests three benefits of having an enemy:

1. The existence of enemies is an incentive for good governance.

The first benefit is that the mere recognition of the enemy’s presence alters how we behave. This is not yet a strategic interaction in which the actions of one side generate the reaction of the other. It precedes the active part of a rivalry. The simple existence of an enemy, even of one that has not acted yet, provokes (or at least, ought to provoke) a change in our posture. Once we acknowledge that a particular enemy exists, we face incentives to modify our outlook for the future, how we prepare for it, and how we organize ourselves.

Naturally, we will be more attuned to the need to develop defensive measures or even, in the direst circumstances, plans to eliminate the enemy. But that is not a way of benefiting from the enemy; it is simply an instinctive reaction spurred by the desire of self-preservation. The beneficial change stems from the fact that the enemy is like a mirror to us, or a critic who points out the foibles and weaknesses we may possess. The enemy is constantly watching us, seeking our weak spots in order to undermine our safety, well-being, or reputation. Plutarch notes, “Your enemy, wide awake, is constantly lying in wait to take advantage of your actions, and seeking to gain some hold on you, keeping up a constant patrol about your life.” An enemy, he continues, “plays the detective on your actions and digs his way into your plans and searches them through and through.”⁵

The presence of a rival that is relentlessly watching us, seeking to damage us through our own faults, is an incentive to improve. In our private lives, the motivation may be the shame of our vices that we hide in order to be able to criticize or take the higher moral ground in front of potential enemies. It is “a peculiar mark of vice that we feel more ashamed of our faults before our enemies than before our friends.”⁶ We want to consider our rivals as morally inferior and thus we worry that they may find something for which we can be reproached. Quoting Antisthenes, a pupil of Socrates, Plutarch stresses this point: “Men have need of true friends or else of ardent enemies; for the first by admonition, and the second by reviling, turn them from error.”⁷ Enemies make us more virtuous.

But this logic is applicable to more than personal moral self-improvement. Plutarch compares the path of virtue of an individual to that of a state. He writes:

For just as states which are chastened by border warfare and continual campaigning become well content with good order and a sound government, so persons who have been compelled on account of enmities to practice soberness of living, to guard against indolence and contemptuousness . . . are insensibly led by force of habit to make no mistakes, and are made orderly in their behavior, even if reason co-operate but slightly.⁸

This mechanism is unlikely to lead every state to become more virtuous—by, for instance, becoming more respectful of human life or gaining a greater appreciation for liberty. The particular political leadership of a state (for example, a Putin or an Assad) may be immune to the reproaching posture of other states. More broadly, there is little global agreement on what a virtuous political regime may be: Western democracies have one view (and even within them there are marked differences on matters such as the meaning and list of “human rights”) that is not fully shared by many non-Western states. This is not to affirm that no objective standards exist and we should accept moral equivalency, but only that the attainment of moral superiority may be a very small incentive for states. As long as a regime or a political leader is firmly in control, or the state is sufficiently powerful to achieve some of its ends, the pursuit of a “life beyond reproach” is not high on the list.

Nonetheless, in the first part of the paragraph cited above, Plutarch suggests a direct relation between international rivalries and internal order. An enemy on the frontier makes the citizens of the threatened state more appreciative of political order and good governance. The most basic aspiration of people is security and, when reminded of the risks to it, they seek to improve their chances of survival. One way to do that is to alter their own behavior: less infighting among themselves, more appreciation for unity. This is Plutarch’s version of a “rally around the flag.”

2. Enemies spur us to be more coordinated and efficient.

The second benefit of having enemies is that people who are engaged in a competition with others seek more effective political leaders, more efficient political regimes, and in general try to improve their capabilities and skills. Plutarch notes that actors or instrument players, “when there is rivalry and competition with another company, . . . apply not only themselves but their instruments more attentively, picking their strings and tuning them and playing their flutes in more exact harmony.”⁹ Competition that arises out of rivalry pushes us to work together and to improve the outcome, be it music in the case of an orchestra or the security provision in the case of a polity.

The enemy provides an organizing principle for our strategy. Without enemies, one lets oneself go, so to speak. The state leadership and institutions become careless in their behavior because there is limited risk for mismanagement, for a mistaken decision or even for a poorly thought out strategy. Plutarch quotes the Roman Nasica who, after the Romans defeated the Carthaginians and Achaeans, argued that Rome was in greater danger now than before the victory: “Now is our position really dangerous, since we have left for ourselves none to make us either afraid or ashamed.”¹⁰ The absence of an enemy who tries to use our weaknesses for his benefit and to our detriment is blissful and dangerous at the same time.

The danger of having no enemy is that it becomes more difficult to think strategically. Policies become agendas, rather than strategies. The absence of an enemy—or the perception that there is no enemy—results in political leaders thinking that the achievement of a particular objective depends merely on a plan and a proper utilization of the necessary resources. With no competition from another actor, no shooting back so to speak, policies are thought to be molding a passive material, akin to chiseling a human form out of a block of marble. What is required then are not strategists, individuals capable of understanding the enemy and endowed with great intuition and skills of adaptation, but managers, individuals calculating the resources needed to implement a scripted agenda.

This is not a hypothetical temptation. It is sufficient to witness the efforts of the EU political leadership to open Europe’s doors to Ukraine in 2014. The EU approach was grounded in the conceit that there were no enemies to the set of principles espoused by Brussels: the benefits of an integrated market, a borderless area, diluted (or “pooled”) sovereignty, and transnational rules were self-evident and appealing to everyone. The opponents, whether in Kiev or in Moscow, were not enemies or rivals; they simply did not comprehend yet the inevitability of this larger trend away from nation states, territorial control, and brute force. Hence, the extension of the European Union’s rules-based order required managerial stamina and not military prowess—a detailed agenda for negotiations, not a strategy for competition. The outcome is well known.

An additional danger of having no enemies is a splintering of the various institutions and individuals within a state. Lacking the organizing principle that the clear presence of an enemy supplies, it becomes more difficult to harness the many actors inside a state toward a common purpose. Narrow bureaucratic interests and the individuals’ search for prestige take over as the primary motivations of state institutions and leaders.

It is difficult to have a grand strategy for a state in any conditions, but perhaps more so in the absence of an enemy when institutional strategies pursued for their narrowly defined benefit and survival become predominant. The preferred bureaucratic option overshadows a larger strategic purpose of the various state institutions and branches. As Emily Goodman notes, “Without clearly established strategic priorities set by civilian leaders, military strategy is likely to become ‘decentralized’ with each service focusing on its ‘preferred’ threats, preparing to fight the type of war most amenable to that service and most likely to provide an autonomous and dominant role for that service.” In such circumstances we can expect “less integration across the services, and less willingness for services to devote resources to supporting missions, like combat air support or strategic lift.”¹¹

The “fog of peace” presents peculiar challenges that may make the state unprepared for future competition and conflict. As institutional selfishness takes over, each organization within the state becomes less capable of coordination and of working together toward the common objective of providing security. To use Plutarch’s analogy mentioned earlier, in the absence of competition, each player plays to his own tune in order to showcase his virtuosity and skills, to attract attention and fame for himself. The orchestra becomes a cacophonous group of glory seeking players.

3. The presence of enemies releases pressures.

Finally, the third broad benefit of having an enemy is, according to Plutarch, the ability to vent emotions. The enemy serves as a punching bag to release pent up passions that otherwise may create discord among friends. As Plutarch puts it, a “man would profit in no moderate degree by venting these emotions upon his enemies, and turning the course of such discharges, so to speak, as far away as possible from his associates and relatives.”¹² Even more, Plutarch writes that “ . . . your enemy, by taking up and diverting to himself your malice and jealousy, will render you more kindly and less disagreeable to your friends in their prosperity.”¹³

As with the previous arguments, this one can also be extended to the political life of a state. Plutarch mentions an example of how the achievement of accord in domestic politics is illusory at best and conducive to even greater strife at worst. A political leader named Demus, “when he found himself on the winning side in a civic strife in Chios, . . . advised his party associates not to banish all their opponents, but to leave some of them behind, ‘in order,’ he said, ‘that we may not begin to quarrel with our friends, though being completely rid of our enemies.’”¹⁴ The claim of a harmonious consensus only leads to new and perhaps more vicious conflicts.

This logic applies also to foreign enemies. The absence of external enemies—or, worse, the naive belief that there are no enemies—is dangerous because it elevates the naturally discordant interests and agendas of the various leaders and political groupings inside the state. The primary concern of the state is then fractured into the pursuit of the narrow interests of factions and individual leaders. It is preferable, Plutarch seems to suggest, to have an enemy so as to release these internal tensions, or at least to subdue them by focusing the attention and the resources of the polity away from itself. Focusing on the differences of opinions or of worldviews is a luxury good that we pursue when no enemies exist—or when we think that there are no enemies because we see the world as a harmonious global community.

The flip side of this last benefit in particular—but of all of them in general—is that enmity can generate hatred. In part the risk is that hatred will prevent a more calculating posture, blinding us to the necessity of prudence. Hatred can lead to unnecessary conflicts with the enemy and to a certain strategic rigidity that does not allow for prudential changes, temporary realignments, or pauses. And as a wise Roman slave, Publilius Syrus, (1^st century BCE), pithily put it: “It is a bad plan that admits of no modification.”¹⁵

More importantly, a long-standing enemy and the hatred this may engender is dangerous because it degrades us. Plutarch writes:

enmity introduces envy along with hatred, and leaves as a residue jealousy, joy over others’ misfortunes, and vindictiveness. Moreover, knavery, deceit, and intrigue, which seem not bad or unjust when employed against an enemy, if once they find a lodgment, acquire a permanent tenure, and are hard to eject. The next thing is that men of themselves employ these against their friends through force of habit, unless they are on their guard against using them against their enemies.¹⁶

In other words, we have to guard ourselves from a posture that is overly mistrustful, undermining the ability to develop and hold allies.

Plutarch concludes his essay with brief advice on what to study in an enemy. Four variables are key according to him: “life, character, words, and deeds.” Interestingly, Plutarch does not include in this list the strength or resources of the enemy. He does not exclude them, and in fact the success of the enemy (or of ourselves) results from “bending all energies” in the chosen direction. But by observing capabilities, we may miss the nature and the intent of the enemy; we focus on what he has as opposed to who he is.

If the question is how to defeat the enemy—or whether the rival presents a clear and present danger—then, presumably, the study of capabilities increases in importance. How we study the enemy depends therefore on the question we ask, and on the level of threat that we expect. The more menacing the enemy, the more important an assessment of his capabilities becomes. But Plutarch does not go this far.

We spent the last few decades in a blissful insouciance of the enduring realities of international politics. The progressive power of globalization would inevitably turn enemies and rivals into friends and partners—and national sovereignty and citizenry would be elevated to a global community and global citizenry. This belief was wrong, and we are slowly waking up to the fact that enemies, from China to Russia and Iran, have spent these years planning how to subvert the international order we built and maintained. We have to compete with them, deter them from further aggressive moves, and preserve the liberty at home that gives us reason to oppose them. And above all, as Plutarch put it, we can turn these enemies to our benefit by strengthening our political order, founded on the recognition of self-evident truths that are independent from the prevailing fashion of the day. Whether we can do that remains to be seen.