The rise of right-wing political parties on both sides of the Atlantic has proved almost incomprehensible to mainstream political commentators. How can modern people in an integrated, cosmopolitan world embrace localism, racialism, and tribal identity?

The migrant crisis, and attacks perpetrated by Muslim terrorists, are commonly cited as reasons for right-wing parties’ successes in Europe. Likewise it has been suggested that the right wing in the United States favors protectionist policies in response to lost manufacturing jobs.

But from a perspective that assumes that political movements are driven by the desire to maximize self-interest (what economists call “utility”) the political commitments of the new right wing are irrational or perverse. How can citizens of wealthy states take up such “backward” attitudes against economic immigrants and political refugees when the costs of admitting such migrants are relatively low, and European birthrates have fallen below the replacement fertility rate? How can those living in advanced capitalist economies raise the specter of natural sovereignty against international trade agreements which would benefit those in the position to invest abroad?

While polls and anecdotes offer evidence that reactionary movements are on the rise, they offer little understanding of their cause. Liberal academics and journalists increasingly resort to a form of non-explanation via invective: right-wingers must be ignorant, racist, or simply stupid. But why is this movement growing globally, and why now?

It is helpful to return to the categories of ancient political psychology: appetite, thumos, and wish. By collapsing these three forms of desire under the single concept of “preference,” contemporary social and political theorists have missed that they are differently motivated and in turn motivate different kinds of actions. In particular, “appetitive” desires — for sensual pleasures like food and sex — are distinct from the thumotic desire for honor and revenge. Making a sharp distinction between thumotic and appetitive desires can help one understand the current state of world politics, regardless of where one’s sympathies lie.

Thumos already had the sense, in Homer’s Iliad, of the seat of emotion and life — a man’s “heart” or central principle of motion — but in Plato’s Republic the term takes on a distinctive political and psychological meaning. In the course of dividing the human psyche into a calculating, rational part and an irrational, appetitive part, Socrates asks where we should put the part that gives rise to anger. His partners in the conversation agree immediately that thumos cannot be rational. But Socrates cites a story to show that thumos cannot be identified with appetite, either:

Leontius, the son of Aglaion, was going up from the Piraeus along the outside of the North Wall when he saw some corpses lying at the executioner’s feet. He had an appetite to look at them but at the same time he was disgusted and turned away. For a time he struggled with himself and covered his face, but, finally, overpowered by the appetite, he pushed his eyes wide open and rushed towards the corpses, saying, “Look for yourselves, you evil wretches, take your fill of the beautiful sight!” (Republic Book IV, 439e-440a Grube and Reeve Trans.)

The dramatic struggle reported here is not between Leontius’ rational and irrational parts, but between two parts of the irrational psyche: appetite and thumos. Leontius’ necrophilic lust for the corpses is pitted against his thumotic sense of shame and disgust at himself for harboring such appetites. This internal conflict, which Socrates introduces to show that thumos can oppose appetite and thus that the two should not be identified, comes to a conclusion with the triumph of appetite, which is dramatically identified by Leontius with his eyes. But his thumotic reaction against his own lust is telling: feeling disgust at its presence, he reacts in rage, cursing his eyes as evil.

Plato argues that the thumos of one who believes he has acted wrongly will not be roused to anger. But when a man feels that he has been wronged, his thumos “boils up.” As he fights for what he feels to be just, he will endure hunger, cold, and other hardships (Republic 440c-d.). Aristotle also picks up on both the boiling, “hot” aspect of thumos and its reactivity or responsiveness to perceived wrongs. In his psychological work, he says that physiologists might define anger as a boiling of the blood around the heart, while the dialectician will define anger as “desire to pay back with pain.” (De Anima I.1, 403a25-403b2). Though Aristotle’s purpose is to raise a distinction between two ways of talking about emotions — one concerning the underlying material of an emotion, the other its reason — both definitions link anger to thumos. To desire to pay someone back with pain depends on the feeling that one has been unjustly wronged and that revenge is the proper response. Aristotle’s physiological account also follows Plato in characterizing the material part of this event as a “zesis” — a “boiling over” of rage.

According to contemporary philosophers of thumos, this seething anger is a quintessential political phenomenon: the response to perceived incursions into what a political actor takes to be his own. In his 2007 Jefferson Lecture, Harvey Mansfield wrote that “Politics is about what makes you angry, not so much about what you want.” For a want to count as political, the political agent must feel entitled to what he wants. As Mansfield puts it, “When you complain, it is not so much that you lack what you want as that you feel slighted or offended in not having what is rightfully yours.” For Mansfield, thumos allows us to distinguish between defending what one feels entitled to as one’s own, and seeking gains. The forgetting of thumos by political thinkers has had the disastrous result of conflating self-righteous defense with “maximizing” appetitive behavior. This makes violent reaction to perceived threats incomprehensible.

In his 2006 book Rage and Time, Peter Sloterdijk takes what is arguably an even more radical stance, turning his critique against democratic capitalism itself. Whereas for Mansfield, thumos has been forgotten in political theorizing, Sloterdijk argues that post-war capitalism itself is unable to allow for expressions of rage. Crucially for Sloterdijk, consumerism, while meeting all the demands of appetite, is unable to offer an outlet for thumotic energies. The result is an inherent instability in the modern state, exemplified by the multiplication of reactionary and terrorist groups in the midst of the most developed capitalist societies.

If we adopt thumos as a term of political significance, then we can begin to offer answers to the questions with which we began, and which could not easily be addressed with the standard liberal or utilitarian vocabularies. Threatened or real reactionary violence against migrants, for example, does not arise from a lack of liberal values or a perverse set of preferences, but from a feeling that the phenomenon of mass migration is an incursion on what is proper to the citizens of the state. Reactions against a trade policy, while sometimes motivated by worries about lost jobs, have a more immediate cause in the feeling that they do damage to the nation-state as an authoritative decision-maker. Moreover, if they are rooted in thumos, such reactions will not be satisfied by a simple change in policy: reactionary movements by nature aim to “pay back with pain” those who have insulted them.

The charm and danger of utilitarianism and liberalism is that they tend toward a utopian fantasy that prudent policy choices could extirpate the desire for revenge once and for all. Such fantasies are exemplified in Thomas Friedman’s theory of the “Lexus and the olive tree” according to which the thumotic impulses of violent fundamentalists in former European colonies could be quelled by the importation of luxury goods from developed Western countries. The fact that fascist ideologies persist in the midst of developed nations offers ever greater evidence that this theory is wrong, and that thumotic desire is more than utility maximization or lack of understanding of the values of freedom and equality.

Thumos is not just a disposition to react to insult. It is a part of human life that must be enlisted for the establishment of political order, but which is always overreaching itself. In Plato’s analogy comparing the parts of the psyche to the parts of the state, thumos corresponds to a guardian class that wields the power to inflict violence on behalf of the political community. This power of violence it is at once constitutive of the political sphere and represents the danger of its collapse. To ignore thumos in our political discussions, and to write off the enraged as crazy or misinformed, is a potentially catastrophic act of ignorance.