Why We Hate

We offer a functional perspective on hate, showing that hate has a unique pattern of appraisals and action tendencies. Hate is based on perceptions of a stable, negative disposition of persons or groups. We hate persons and groups more because of who they are, than because of what they do. Hate has the goal to eliminate its target. Hate is especially significant at the intergroup level, where it turns already devalued groups into victims of hate. When shared among group members, hate can spread fast in conflict zones where people are exposed to hate-based violence, which further feeds their hate. Hate can be reassuring and self-protective, because its message is simple and helps confirming people’s belief in a just world.


Introduction
In a comprehensive review of classic as well as more contemporary conceptualizations of hatred, Royzman, McCauley, and Rozin (2005) described hatred as the most destructive affective phenomenon in the history of human nature. These destructive implications of hatred on human life have been widely documented in several recent contributions (e.g., Halperin, 2011;Levin & Nolan, 2015a, 2015bOpotow & McClelland, 2007;Sternberg, 2005;Sullivan, Ong, La Macchia, & Louis, 2016). This literature shows that hate has been defined in a variety of ways, a problem characteristic for emotions in general. Hate has been considered an emotional attitude (Ekman, 1992), a syndrome (Solomon, 1977), a form of generalized anger (Bernier & Dozier, 2002;Frijda, 1986;Power & Dalgleish, 1997), a generalized evaluation (Ben-Ze'ev, 2000), a normative judgment (McDevitt & Levin, 1993), a motive to devalue others (Rempel & Burris, 2005), or simply an emotion (Elster, 1999). Despite these different views, it is remarkable that there is little theorizing about hate, although the topic seems to be getting increasing attention in recent years. Even more surprisingly, there is not much in-depth empirical research on hatred, especially not in psychology. Interestingly, other disciplines, such as sociology, political science, communication, and social justice research have provided interesting new empirical data, in particular on hate crime and hate speech.
The fact that hate is an underresearched topic in psychology may be due to several factors. First, hate is a phenomenon that is complex to empirically investigate with the standard psychological methods and samples. The standard student population of the majority of psychological studies report that they have never experienced hate (e.g., Aumer, Krebs Bahn, & Harris, 2015;Halperin, 2008). For example, Halperin (2008, Study 1) aimed to examine people's lay theories of hatred. For that pur-pose, he asked 40 Israelis to think of one event in their lives in which they felt hatred. All 40 interviewees immediately said that they had never experienced hatred. They further stated that they had felt extreme anger, that they knew other people who experienced hatred, and that they were aware of the prevalence of hatred in conflict zones. But to feel hatred towards other people? Not them. Ironically, some of the participants who said that they had never hated someone throughout their entire lives then described specific situations in the history of the Israeli-Palestinian conflict in which they had wanted to throw a bomb on a large Palestinian city, or situations in which they wanted to do everything to annihilate or destroy the Palestinians. These examples illustrate the social inappropriateness of hate and the unwillingness to acknowledge feeling such a destructive emotion.
Second, hate has never been conceived as a standard emotion and thus did not gain from the rising popularity of the psychological study of emotions in the last decades. For example, in most empirical investigations based on appraisal theories (e.g., Roseman, 1984;Scherer, 2005), one can find emotions such as dislike, anger, or contempt, but hate is systematically lacking (but see Fitness & Fletcher, 1993;Halperin, 2008). In this review, we will try to make up for this lack of attention, and analyze the literature on hate from different disciplinary perspectives and at different levels of analysis. We will start with defining the characteristics of hate, and addressing the question whether hate is an emotion or something else, or both. Second, we will move on to the analysis of hate at different social levels (from individual to intergroup). Third, we will analyze how and why hate spreads, including hate crimes and hate speech. Fourth, we will discuss the role of hate in society. Finally, we will end with a reflection on the role and function of hate at different levels of analysis and will then offer some future venues of research.

What Are the Characteristics of Hate?
Most authors who have written on hate agree that it is a powerful negative emotional phenomenon (Aumer-Ryan & Hatfield, 2007;Royzman et al., 2005;Sternberg, 2003), although not all scholars would define it as an emotion. Hate is assumed to develop when others mistreat or humiliate someone, or whose deliberate actions have become an obstruction to someone's goals (Aumer-Ryan & Hatfield, 2007;Baumeister & Butz, 2005;Royzman et al., 2005;Sternberg, 2003). Hate obviously shares characteristics with several other negative emotions, especially anger, contempt, or moral disgust (Fitness & Fletcher, 1993;Frijda, 1986;Halperin, 2008;Oatley & Jenkins, 1996). Indeed, hatred is partly characterized by features that are not unique to hatred. To make the demarcation with other emotions even more complex, it is highly likely that hate feelings are often accompanied by other negative emotions, maybe especially because hate is such an intense feeling. For example, individuals may report hate if appraising an event as contradicting their goals and interests (relevant to all negative emotions), perceiving the other's behavior as unjustified and unfair (characteristic of anger), morally inferior (characteristic of contempt), or morally nauseating (prototypical for disgust). In other words, anger, contempt, disgust, humiliation, revenge feelings, and hate can all be elicited in reaction to a similar event, namely when another's action is perceived as negative, intentional, immoral, or evil (Haidt, 2003;Rozin, 1999).
The question then is whether and how hate is different from these closely related emotions. We argue that we can theoretically distinguish these emotions on the basis of their appraisal patterns, action tendencies, and motivational goals. With respect to appraisals, hate is different from anger, because an anger target is appraised as someone whose behavior can be influenced and changed (Fischer & Roseman, 2007;Halperin, 2008;Halperin, Russell, Dweck, & Gross, 2011). A hate target, on the contrary, implies appraisals of the other's malevolent nature and malicious intent. In other words, hate is characterized by appraisals that imply a stable perception of a person or group and thus the incapability to change the extremely negative characteristics attributed to the target of hate (Allport, 1954;Royzman et al., 2005;Schoenewolf, 1996;Sternberg, 2003). Its appraisals are targeted at the hate target itself, rather than at specific actions carried out by that target (Ortony, Clore, & Collins, 1988). While we feel anger because a certain action by a certain person or group is appraised as immoral, unfair, or unjust, if that very same person changed their behavior, the levels of anger would be reduced and the person would be forgiven. However, the entire configuration of hatred appraisals focuses on the innate nature, motives, and characteristics of the target itself and therefore a momentary change in certain behavioral patterns will not necessarily diminish levels of hatred. One hates one's father because he is perceived as a bad father in one's entire youth, not just once. An individual hates his wife because she has betrayed him and humiliated him deeply and repeatedly. In such cases, there is nothing the hate target can do to make up or repair. The other is malicious, not just acts maliciously. This assessment also contributes to feelings of powerlessness, which have often been reported as a characteristic condition in the development of hate (Sternberg, 2005). Indeed, Fitness and Fletcher's (1993) prototype analysis of hate (vs. anger, jealousy, and love) shows that the concept of hate includes low levels of control, high levels of obstacles, and intense unpleasantness, because one feels badly treated, unsupported, humiliated, ignored, or uncared for. This sense of powerlessness may be fed by the appraisal that hate targets are dangerous and may execute their malicious intentions at any time.
In short, on the basis of preliminary evidence we propose that when individuals experience hate, they typically perceive their hate target as having malicious intentions and being immoral, which is accompanied by feelings of lack of control or powerlessness. Such appraisals are not the result of one specific action, but of a belief about the stable disposition of the hated person or group. This stable and dispositional attribution of negative characteristics to the target of one's emotion can also be found in appraisals of contempt (see also Halperin, 2008;Jasini & Fischer, 2018) and disgust (Russell & Giner-Sorolla, 2011). In the case of contempt, however, the target of one's emotion is seen as inferior (Fischer & Giner-Sorolla, 2016), and in the case of disgust, appraisals are more specifically related to violations of a moral code in relation to what happens with one's own body, such as bodily contamination (Fischer & Giner-Sorolla, 2016). Appraisals of humiliation are more specific than those of hate, entailing the appraisal of a specific act as extremely derogating and a threat to one's self-worth (see e.g., Mann, Feddes, Doosje, & Fischer, 2016), which is also the case for feelings of revenge (see Seip, 2016). In sum, the core set of appraisals of hate seems to be the attribution of stable and malicious intentions to the target, accompanied by appraisals of danger and feelings of powerlessness.
However, the main difference that make hate stand out from other negative emotions can be especially found in its action tendencies and emotivational goals. According to Roseman, Wiest, and Swartz (1994), an emotivational goal reflects what the emotion tries to bring about, and thus drives the emotional experience. Action tendencies are very closely associated with emotivational goals as they reflect the emotional impulse to act on a specific goal (see also Rempel & Burris, 2005). The coercion goal for example is closely associated with the tendency to attack someone (either verbally or physically), and the exclusion goal is associated with the tendency to ignore or look down on someone (Roseman et al., 1994). Emotivational goal can implicitly be found in others' theorizing as well. White (1996) for example describes hatred as the desire to harm, humiliate, or even kill its object-not always instrumentally, but rather to cause harm as a vengeful objective in itself. Bar-Tal (2007) also suggested that hatred is a hostile feeling directed toward another person or group that consists of malice, repugnance, and willingness to harm and even annihilate the object of hatred. Whereas anger implies a coercion goal, that is, the motive to change another person by attacking, confronting, or criticizing, contempt implies an exclusion goal (Fischer & Roseman, 2007), motivating individuals to exclude others from their social environment (Halperin, 2008;Halperin, Canetti, & Kimhi, 2012;Jasini & Fischer, 2018). Adopting a social functional perspective on emotions (e.g., Fischer & Manstead, 2016;Keltner & Haidt, 1999), we propose that the emotivational goal of hate is not merely to hurt, but to ultimately eliminate or destroy the target, either mentally (humiliating, treasuring feelings of revenge), socially (excluding, ignoring), or physically (killing, torturing), which may be accompanied by the goal to let the wrongdoer suffer (Ben-Ze'ev, 2008). Although actions and expressions related to hate, anger, contempt, disgust, humiliation, or revenge can be similar, their emotivational goals are different (see Figure 1). Anger has the emotivational goal to change the target (e.g., by attacking), contempt has the goal to socially exclude (e.g., by avoiding or derogating), and revenge has the goal to restore the equity in suffering and deter (Seip, 2016). Humiliation has shown to have different goals, depending on the specific context: to withdraw and protect oneself (Mann et al., 2016) or to rehumiliate, that is, take revenge.
How exactly the emotivational goal of hate is translated into a specific action will differ, depending on why someone has developed hate and what the relation between the victim and perpetrator is. The best way to eliminate the parent one hates, for example, is to completely ignore them and ban them entirely from one's life, whereas the best way to destroy hated CEOs may be to derogate, ridicule, and scorn them. In extreme occasions, violence or actual murder may be a viable option, but if this is not feasible, then one can cherish feelings of revenge. We will come back to the relationship between hater and the hated later in this review.

Long Term Sentiment or an Emotion?
Scholars of hatred have continually debated the question of whether hatred is an emotion, a motive (Rempel & Burris, 2005), or an (emotional) attitude or syndrome (Royzman et al., 2005). This debate is driven by the fact that one of hate's core characteristics is that it generally lasts longer than the event that initially evoked it. The enduring nature of hatred is based in the appraisals that are targeted at the fundamental nature of the hated group. Given that hate is often not a reaction to a specific event, and not limited to a short period of time, the question is raised whether hate actually is an emotion, or rather an emotional attitude or sentiment (Allport, 1954;Aumer-Ryan & Hatfield, 2007;Frijda, 1986;Frijda, Mesquita, Sonnemans, & van Goozen, 1991;Halperin et al., 2012;Royzman et al., 2005;Shand, 1920, as cited in Royzman et al., 2005Sternberg, 2005). In the last two decades, scholars (e.g., Fischer & Giner-Sorolla, 2016;Halperin, 2008;Sternberg, 2003) have resolved this contradiction between emotions and sentiments by suggesting that some "emotions" can occur in both configurations-immediate and chronic, and thus can be conceived of as a (short-term) emotion as well as a (long-term) sentiment. In-depth interviews by Halperin (2008) with people who were asked to describe their own subjective experience of hatred indeed suggest that more than half of the participants report an ongoing emotional experience (i.e., an enduring sentiment), while the remainder focused on a more acute event of hate (Halperin, 2008). Halperin et al. (2012) describe the sentiment hate, specifically in intergroup contexts, as a stable and familiar "hating" emotional attitude ("chronic hatred"), which organizes people's social world and helps strengthening the connection to the ingroup ("ingroup love") at the expense of various outgroups ("outgroup hate"). To prevent future painful offenses by the hated group, the goal of the hate sentiment is to eliminate this group from their environment, for example through an absolute separation from members of the other group.
Everyday observations also suggest that hate is so powerful that it does, not just temporarily but permanently, destroy relations between individuals or groups. An illustration comes from a story of a 20-year-old Kosovar Albanian woman who was asked to describe an experience of hatred in the context of a study by Jasini and Fischer (2018): Hate can thus remain long after an incident, and therefore can take a different form than a short-term emotional reaction to a specific event (like anger or disgust).
The emotion hate (also referred to as "immediate hate"; Halperin et al., 2012) is much more urgent and occurs in response to significant events that are appraised as so dramatic that they lead to the kind of appraisals (e.g., "the ougroup is evil by nature") and motivations (e.g., "I would like it to be destroyed") that are usually associated with hatred. This intense feeling is often accompanied by unpleasant physical symptoms and a sense of fear and helplessness (Sternberg, 2003(Sternberg, , 2005. It provokes a strong desire for revenge, a wish to inflict suffering, and, at times, desired annihilation of the outgroup. Studies by Halperin et al. (2012) unequivocally show that people are capable of short-term hate, following an unusual, mostly destructive, and violent event. In that very short period of time, they attribute the negative behavior of the outgroup to its innate evil character.
The two forms of hatred are related, yet distinct, and one fuels the occurrence and magnitude of the other. Frequent incidents of the emotion hate may make the development of the sentiment more probable (see also Rempel & Burris, 2005). At the same time, the lingering of hate as a sentiment constitutes fertile ground for the eruption of hate. Chronic haters, who encounter their targets or the consequences of their targets' actions, most likely react with immediate hatred. These people evaluate almost any behavior of the hate target through the lens of their long-term perspective that the hate target is malevolent. As such, haters are probably more susceptible than others to systematic biases, such as the fundamental attribution error (Ross, 1977). What follows is that the mere presence, mentioning, or even internal recollection of the hated person or group can fuel hate as a sentiment. At the same time, the causal mechanism can work the other way as well. Repeated events of immediate hatred can very easily turn the hatred feeling into an enduring sentiment. Indeed, it is only natural that after repeated violent events of that kind, it becomes very difficult for people to forget earlier instances, and such feelings remain present for longer periods of time. In a way, hatred is an emotion that requires more time to evolve, but once it happens it takes much longer to dissolve, and it will always leave scars.

Hate at an Interpersonal Level
One important factor in the development of hate, compared to most other negative emotions, is the relationship between the person who hates and the target of this hate. In the previous section, we have described the goal of hate to eliminate or destroy. Interestingly, at an interpersonal level, the relationship between hater and hated can be intimate. Studies by Aumer et al. (2016) for example show that when individuals were asked to report on a person they currently love but at one time hated in the past, in contrast with a person they loved and never hated, they report in both cases on persons they know very well, such as family members, romantic partners, or colleagues. However, not surprisingly, the quality of the current relationship with the person whom was once hated, was shown to be characterized by less intimacy and love, and more hate. Indeed, in another study of hate and love in close relationships, hated persons were found to be perceived as less open, less agreeable, less conscientious, and less emotionally stable than loved ones (Aumer et al., 2015). Thus, although at an interpersonal level hated persons are often intimates, suggesting that love and hate are not necessarily diametrically opposed (Ben-Ze'ev, 2008), the quality of the relationship with a person one once hated is less satisfactory (Aumer-Ryan & Hatfield, 2007;Rempel & Burris, 2005).
This more negative quality of relationships in which hate is involved is not restricted to marital or family contexts, but can also occur in work contexts, where hate has been found to be associated with experiences of humiliating and demeaning treatment (Fitness, 2000;Fitness & Fletcher, 1993). This is especially the case when such treatment comes from others who are considered as more powerful than oneself (Fitness, 2000). It may be expected that recurrent experiences of humiliation, ridicule, or public shame by a partner or coworker may contribute to the development of intense hate towards them. In addition, previous hate feelings towards the other may leave traces of hurt feelings and resentment, which may put a strain on the relationship. These different lines of research thus suggest that past occurrences of hate seem to linger on in current relationships and are not forgotten, nor completely forgiven. From an emotion theoretical perspective this makes sense, because we can only have intense and extreme emotions such as love and hate when the objects of these emotions touch upon our concerns (Frijda, 1986). In other words, we cannot love or hate persons we are indifferent to. Although we maybe would like or pretend not to care, and to easily forgive or forget, we do care about the neglecting, aggressive, or disgusting character of another person, especially if we once loved this person.
When moving from an interpersonal to an intergroup level, it is interesting to observe that we do not need to know the persons we hate. It is very well possible to hate groups because of what they represent (in terms of power, values, past behaviors, identity). People may hate Germans for what they did during WWII, even though they do not know any German involved in these atrocities. People may hate homosexuals or lesbians because they think that they are deviants from human nature, even though they do not know any such person. The hatred of groups, thus, does not require a personal connection with a member of this group. In such cases, there is only a symbolic relationship with a group member on the basis of one's perception of this person as part of a negative outgroup.

Hate at an Intergroup Level
Similar to other intergroup emotions, intergroup hate is an emotion experienced on behalf of one's own group and targeting the outgroup. Intergroup emotions are instigated by events that advance or threaten the ingroup (Mackie, Devos, & Smith, 2000). For instance, if group members perceive that their ingroup is unjustly treated or humiliated by another group, they may experience negative emotions towards outgroup members as well as form negative attitudes about them. In addition, the strength of identification with the ingroup may contribute to the intensity of intergroup emotions, with high compared to low identifiers generally reporting stronger emotional experiences (Gordijn, Yzerbyt, Wigboldus, & Dumont, 2006;Iyer & Leach, 2009;Yzerbyt, Dumont, Wigboldus, & Gordijn, 2003).
Intergroup hatred is directed at a particular outgroup, aiming to eliminate the group (e.g., Halperin, 2008Halperin, , 2011Halperin, Canetti-Nisim, & Hirsch-Hoefler, 2009;Halperin et al., 2011). Hate at the intergroup level requires a clear distinction between the ingroup and the outgroup, and is facilitated by the perception that the outgroup is a rather homogeneous entity. The perception of outgroup homogeneity is essential for people to be able to generalize from a negative behavior of a single outgroup member to appraisals targeted at the entire outgroup. For example, a Palestinian who suffered from an abusive behavior of an Israeli soldier in a military checkpoint will develop hate towards all Jews only to the extent that she believes that all Jews are the same, and that the behavior of that one soldier actually represents the innate characteristics of the entire Jewish people (for similar ideas, see Er-rafiy & Brauer, 2013;Simon & Mummendey, 1990). Especially a loathed outgroup that has attacked the interests of the group, makes the ingroup identity salient and is most likely to become the target of one's hate.
Studies on intergroup hate show very similar patterns of appraisals and motives to those that we have reported for interpersonal hate. In a study on the appraisals of hate and two related emotions (anger and fear), Halperin (2008, Study 2) provided Israeli participants with a questionnaire that included a detailed description of four emotionally conflicting scenarios (e.g., a terror attack, intergroup violent event in a nightclub), followed by a manipulation of the cognitive appraisals of the protagonist in the story regarding five dichotomous appraisal dimensions: (a) just/unjust event, (b) outgroup/circumstances were responsible, (c) intentional/unintentional harm, (d) outgroup is evil/not evil, and (e) low/high coping potential. After reading the scenario and the protagonist's appraisals, participants were asked to rank the extent to which the protagonist experienced hatred, fear, and anger (separately) in response to that event. The results support the assumption that hate has two unique appraisals: outgroup harm is intentional and due to their stable, evil character. On the other hand, the attribution of responsibility to the outgroup and the appraisal that the event was unjust were found for both hatred and anger, and the appraisal of low coping potential (powerlessness) was found for both fear and hatred. Jasini and Fischer (2018) found a similar pattern of appraisals for intergroup hate in their study in another specific intergroup context, namely in Kosovo. The study was conducted with Albanian Kosovars who suffered ethnic cleansing by Serbian (para)militaries during the Kosovo War (1998)(1999). They asked Albanian participants to imagine an interpersonal assault carried out by Serbian individuals, and then to rate the emotions and appraisals in response to the event. They found that-after controlling for anger-the intensity of hate was positively associated with appraisals of malicious intent and immorality, and marginally with powerlessness.
Intergroup hate can also be characterized by specific emotivational goals and action tendencies. Jasini and Fischer (2017) found that hate was positively associated with the goal to take revenge and to exclude the other, and with the tendency to attack (and not to forgive or withdraw). This is in line with the findings from Halperin (2008, Study 1). Participants in this study (83.3%) stated that they would have wanted something very bad to happen to the hated group and its members. In another study (Halperin, 2008, Study 3), Jewish-Israelis were asked for their emotivational goals and action tendencies in reaction to certain Palestinian actions. The results showed that group-based hatred is characterized by specific emotivational goals mentioned earlier: to do harm to, to remove, and even eliminate the outgroup. Such goals are accompanied with specific action tendencies such as the tendency to attack and not forgive (Jasini & Fischer, 2018) or the tendency to engage in a violent action with the hated people, up to a point where respondents supported the killing of members of the outgroup (Halperin, 2008, Study 1). Still, in the latter study with Israeli participants, only a few participants (16.6%) reported the actual execution of a violent action. The three most common actions reported by the participants were complete detachment from the object of the hatred (83.3%), delight at the failure of the hated other (36.6%; see also Smith & van Dijk, 2018;van Dijk & Ouwerkerk, 2014), and political action taken against the other (56.6%). In short, intergroup hate follows the pattern of interpersonal hate and is characterized by appraisals of harm or malicious intent on the part of the outgroup, reflecting their evil nature. This can lead to the goal to take revenge and to eventually eliminate the outgroup from one's environment. The bodily aspect of collective hatred seems less salient than the cognitive and motivational elements, although we assume it may sometimes also include unpleasant physical symptoms (Sternberg, 2003(Sternberg, , 2005, particularly when the hate is collectively experienced, for example, during a mass demonstration or a sports event. Behaviorally, hate can lead to actual attempts to eradicate the outgroup (White, 1996). Extensive research has demonstrated that, in some situations, there is a connection between hate and its various active political manifestations, such as outgroup exclusionism (Leader, Mullen, & Rice, 2009), terrorism (Sternberg, 2003), the motivation to fight and kill in battle (Ballard & McDowell, 1991), and hate crimes (Berkowitz, 2005). We should note, however, that the (behavioral) expression of hate can differ, depending on the relation between ingroup and outgroup, the (violent) history between the two groups, the specific incidents that have taken place, the dominant (negative) narratives about the outgroup, and the possibility to act upon one's hate. For example, one can be motivated to destroy the outgroup out of perceived self-defense, driven by fear, or one can hate a powerless outgroup, which may be accompanied by contempt and could lead to actions to completely ban the group from one's environment. Still all these forms of hate seem to share the common goal to eliminate the hate target, either physically or socially. In other words, while fear can sometimes lead to flight rather than fight tendencies and anger can lead to constructive rather than destructive corrections (see Fischer & Roseman, 2007;Halperin, 2011;Halperin et al., 2011;Reifen Tagar, Federico, & Halperin, 2011), hatred will always motivate people for destructive action. The belief in stable, extremely negative characteristics implies that there is no merit in trying to correct or improve the outgroup's behavior, and as such, only more extreme reactions seem applicable.

How Hate Spreads
There is abundant evidence that many emotions can be experienced at both an individual and group level. Yet, not all emotions have the same potential to transcend from the individual to the group or collective level. We think that hatred can more easily go through a transformation from individual to group level than other negative emotions; some will even claim that it is the most "group-based" emotion. Aristotle succinctly states that whereas anger is customarily felt toward individuals, hatred is often felt towards groups (see also Ben-Ze'ev, 1992). One reason for this can be found in the core characteristics and the nature of hate. We have argued and shown that hate is based on the generalized attribution of an action to the basic traits and features of a person. In other words, the specific antecedent event of one hateful incident may become less important over time, and the character of the person or group becomes the sole reason for the hate. Generalizing these characteristics to members of a group further enables a parsimonious justification of one's hate. This facile transition of hatred from the interpersonal level to the group level makes it a pivotal agent in group-based political dynamics in general and in intergroup conflicts in particular.
There are three factors that further contribute to the flourishing of hate specifically at the intergroup level. First, hate seems often shared among ingroup members (see Jasini & Fischer, 2018). According to Rimé (2009), the extent of sharing one's emotions is influenced by the intensity of the emotional experience, and the primary targets of sharing generally are close family members and friends. In contexts where intergroup relations are tense, groups share collective narratives about their own group and other groups. For example, previous studies on social sharing have found that people who are victims of violence and ferocities and thus experience collective trauma, often share their emotional experience with other group members (Rimé, 2009). In intractable conflicts, collective narratives are dominated by the memory of past victimization and by ongoing intergroup violence (Bar-Tal, Chernyak-Hai, Schori, & Gundar, 2009;Canetti, Elad-Strenger, Lavi, Guy, & Bar-Tal, 2017;Noor, Shnabel, Halabi, & Nadler, 2012;Vollhardt, 2012). Thus, collective victimhood evokes sharing one's feelings about the target of hate with similar others. Knowing that other ingroup members experience an event in a similar way further reinforces the experience and expression of one's own emotions (see also Manstead & Fischer, 2001). The sharing of strong negative emotions can in turn strengthen feelings of collective victimhood that may make the original feeling of hate even more intense and enduring (see also Bar-Tal, Halperin, & De Rivera, 2007;Kuppens, Yzerbyt, Dandache, Fischer, & van der Schalk, 2013). Thus, sharing past negative emotional experiences caused by an outgroup increases the probability for the development of intergroup hatred (see also Jasini & Fischer, 2018).
Second, while collective victimhood keeps the memory of hate alive across generations, it may also direct the appraisal of future events. Accumulated group knowledge on the immoral and violent behavior of an outgroup affects the evaluation of future behavior, thereby confirming the sentiment that the outgroup is a homogeneous malicious entity. In the eyes of those who see themselves as part of a transgenerational victimized group, the outgroup is malicious, even though they did not personally suffer from the outgroup behavior, or only for a relatively short time. The fact that the outgroup's behavior is considered consistent across generations reflects on its innate negative characteristics. Moreover, shared appraisals on similar emotional events reinforce the emotional fit between individuals and their cultural group (De Leersnyder, Boiger, & Mesquita, 2015), as does identification with the group (Delvaux, Meeussen, & Mesquita, 2015). In turn, the emotions also influence selfcategorization, suggesting that similar emotions strengthen feelings of belonging to the same group (Livingstone, Spears, Manstead, Bruder, & Shepherd, 2011;Porat, Halperin, Mannheim, & Tamir, 2016).
A final and third interesting aspect of hatred that makes it more susceptible to become an intergroup sentiment that spreads fast, is the fact that it can increase in the absence of any personal interaction between the hater and members of the hated group. According to Jasini and Fischer (2018), the lack of personal interactions with the targets of one's hate further diminishes chances of perspective taking from the side of the victim. Allport (1954) already mentioned the lack of direct interaction as one of the most powerful engines behind hate and prejudice. According to his approach, supported by studies in the framework of contact theory (e.g., Pettigrew & Tropp, 2006), lack of direct interaction amplifies hate because the negative appraisal of the malicious character of the group will never be reappraised or contradicted by other information. For example, since Israel completed the construction of the separation wall, Jewish Israelis do not need to suppress their hate towards the Palestinians anymore, because the wall prevents direct encounters with individual Palestinians. Thus, Israelis are not confronted anymore with exceptions to the Israeli view of Palestinians and the hateful image of the Palestinians can easily remain intact. This does not necessarily mean that social interactions with hated group members automatically reduce hate. However, under the right circumstances, haters may learn more about the motives and circumstances of the hated group's actions, which could result in some perspective taking.

Hate Crimes and Hate Speech
One specific way in which intergroup hate spreads in a society is through hate crimes. According to Levin and McDevitt (2008) "hate crimes are criminal offenses motivated either entirely or in part by the fact or perception that a victim is different from the perpetrator." In most cases, this difference is not based on individual characteristics, but on assigned social identities, such as being Black, woman, lesbian, or Muslim. The word hate crime is fairly recent and was used in the US in the late 1980s to describe a racial incident in New York where a Black man was killed for no apparent reason. Since then, there has been much debate about hate crime, which has recently lead to a new field of research in some countries referred to as "hate studies" (Chakraborti & Garland, 2015). Hate crimes are based on stereotypes, prejudice, or extreme negative sentiments about certain groups, and generally also targeted at visible social groups, such as Blacks, Jews, Native Americans, or homeless people. The goal of hate crimes is to communicate a certain message to the group that the haters want to terrify or eliminate.
An important feature of hate crimes is that the victims generally have not done anything specific: they are terrorized for who they are, not for what they have done. This makes the victims feel powerless and unable to control the situation because changing their behavior or attitudes would not help. Levin and McDevitt (2008) distinguish between four types of hate crimes that are based on the offender's motivations: thrill, defense, retaliation, and mission. Whereas the first type is a form of thrill seeking (mostly by groups of teenagers), the second motivation is based on anger and fear, and is considered a strategy to defend a way of living against intruders. This type of crime is mostly committed by single persons who feel threatened, for example, by a Black family who moves into a White neighborhood, or a homosexual teacher hired by a school. The retaliatory third type of hate crime also seems to involve actual hate and is seen as an act of revenge against previous hate crimes or terrorist attacks. For example, after the terrorist attacks in September 2001, there was a 1.6% increase in anti-Muslim hate crimes reported to local police departments in the US. Finally, the last motivation for hate crimes is the mission, which is less frequent and is defined by the fact that the perpetrator is on a moral mission to destroy outgroup members who are not considered human.
In another line of research, hate crimes have been associated with a threatened belief in a just world (Lerner, 1980). The just world belief implies that individuals generally believe that the world is a fair place to live in, and that justice is being done such that people get what they deserve. When an individual becomes the victim of a hate crime on the sole basis of his or her group identity, observers may start restoring their belief in a just world by derogating the victim (see also Sullivan et al., 2016). More importantly, the absence of punishment signals that the violence not only against one individual but against a whole group is justified.
Whereas hate crimes can occur in many forms, it is obvious that the rise of the Internet and the use of social media have been crucial in spreading hate, because hate messages now have a worldwide audience. The number of organized hate groups and hate-advocating sites has increased, and so has the exposure of potential victims to hate messages. In a recent study on the exposure of young adults to hate messages in four different countries (US, Finland, UK, and Germany), Hawdon, Oksanen, and Räsänen (2016) found that 53% of the Americans, 48% of the Fins, 39% of the British, and 30.5% of the Germans had been exposed to hateful messages in the past 3 months. The authors explain this country difference on the basis of differences in hate speech laws. These are almost nonexistent in the US, whereas there are relatively strict antihate speech laws in Germany. This question has indeed evoked a debate on the most efficient legislation with regard to hate crime. According to some scholars (e.g., Cavadino, 2014), the emphasis on the punishment of hate crime has not reduced it, nor helped the victims, and therefore other ways to prevent hate crimes may be more successful. The problems with hate crime law are obviously also related to the fact that it is unclear whether victims always report hate crime. Most researchers assume underreporting, either because people do not expect to be taken seriously or because they ignore and deny their feelings related to the incident as a way of coping with it, or because of fear, or simply because they expect the perpetrators will not be punished anyway (Perry, 2003). Research relating hate crime to the belief in a just world, however, clearly suggests that the absence of punishment may increase hate and hate crimes because it signals that the victim and even the whole group to which the victim belongs deserves this fate. This consequence is especially present for hate crimes because, in contrast with other crimes, the absence of punishment emphasizes the justification of the hatred.

Hate in Politics and Society
Some characteristics of a culture or society form fertile grounds for the development of hate. In his book on the roots of evilgenocide and mass killing- Staub (1989) argues that, first of all, difficult life conditions such as extreme economic problems leading to poverty of large groups of people, but also political, criminal, or institutional violence, facilitate evil intentions. The second set of features refers to culture, especially the rigidity or adaptability of a society. The more rigid the cultural values in a society, the more difficult it is to cope with changes or disturbances of one's traditional values and ways of life. According to Staub (1989), this may lead to scapegoating, trying to protect oneself and one's group to defend one's way of life, safety, health, and values. Blaming others helps to fulfill these needs in times of chaos and uncertainty, and this forms the basis for the development of hate towards groups in society that are seen as the cause of all problems. Other characteristics, such as strong leaders, strong respect for authority, nationalism, and a slow progression of devaluing outgroups are the further ingredients for the slow but steady development of societal hate (Staub, 1989). Waller (2002) refers to this latter set of characteristics as collective potentiation, the social augmentation of individual actions in a group, whether good or bad. In the case of hate, it may refer to all the characteristics of a society or culture at a specific point in time when the devaluation of an outgroup may turn into real hate, and activate its associated goals to annihilate that group.
Under such conditions, the initial development of hate can be a consequence of short-term conflict-related events, but then may automatically result in support for initiating violent actions and for further escalating the conflict. That is also the reason that Staub (2005) and others (e.g., Petersen, 2002;Volkan, 1997) have pointed to hate as the most dominant emotion in past and recent mass murders and genocide (see also Mishra, 2017). If one is convinced of the destructive intentions of the outgroup and feels total despair regarding the likelihood that the outgroup will change its ways, the violent alternative may seem the only reasonable and successful way out. Indeed, research has shown that feelings of hatred may increase the tendency to support extreme military action toward outgroups (e.g., Halperin, 2011). The perception of increased threat is a powerful amplifier of hatred. Ongoing terrorist attacks elicit stress, fear, and uncertainty (Canetti, Russ, Luborsky, Hobfoll, & Gerhart, 2014), and become fertile ground for increasing hate for groups perceived as responsible for the turmoil. Additionally, the aftermath of such events demonstrates that perceived security threats prevail over other issues, such as individual rights and freedoms (Canetti-Nisim, Ariely, & Halperin, 2008).
Hate has also been described as part of a broader societal sentiment coined "ressentiment" (Betz, 1994; but see Salmela & von Scheve, 2017) in theories on the growing support of rightwing populism. These scholars consider hate as part of a cluster of negative emotions. In particular, feelings of insecurity and shame can easily be transformed into anger, resentment, and hate towards other groups, like immigrants, refugees, or the political elite (Salmela & von Scheve, 2017). However, whereas various negative emotions may play a role in mobilizing people to support outgroup derogation and even violence, and to oppose compromises for peace and forgiveness, we think that intergroup hate is the most powerful one. There are two main reasons for this. First, hate is associated with very low expectations for positive change and with high levels of despair, and as a consequence, its associated political action tendencies are by definition destructive rather than constructive. If one does not believe that positive change in the outgroup's violent and immoral behavior is possible, then constructive political reactions-like negotiations, compromises, gestures, or even apologies, which are usually meant to establish more friendly relations-seem just irrelevant (see also Tausch et al., 2011). In addition to that, the emotional goal associated with hate, namely to do destroy or eliminate the outgroup, also leads to one-sided political actions that do not leave any room for positive or constructive change. This is apparent from the hate speech spread by ISIS, who describes their online propaganda as "the Internet army" (Shaaban, 2015).
Hate can even be a destructive force in the midst of peace negotiations. Two studies found that individuals who experienced short-term episodes of hatred in times of negotiations in the Middle East expressed an emotional goal of harming and eliminating the opponent (Halperin, 2008). They likewise tended to reject any positive information regarding the opponent (i.e., lack of openness) and opposed the continuation of negotiations, compromise, and reconciliation efforts (Halperin, 2011). Importantly, given that hatred is associated with a fundamental negation of the outgroup as a whole, and not merely of the group's concrete actions or behavior, those who feel hatred toward the outgroup oppose even the smallest gestures and symbolic compromises, thus refusing to even entertain new ideas that may lead to peace. Two experimental studies conducted in 2011 on the eve of an important peace summit between Israelis and Palestinians show that inducing anger toward Palestinians increased support for making compromises in upcoming negotiations among those with low levels of hatred, but decreased support for compromise among those with high levels of hatred .
There is also evidence that hate fuels political intolerance. Political intolerance is the support or willingness to denounce basic democratic values and equal rights of individuals who belong to a defined outgroup in a particular society (Gibson, 2006;Stouffer, 1955) and is considered one of the most problematic phenomena in democratic societies. Results of four large-scale nationwide surveys among Jews in Israel showed that intergroup hatred is the most important antecedent of political intolerance. It has a stronger effect in the face of heightened existential threat and is especially present among politically unsophisticated individuals-that is, those lacking exposure to political information, intellectual capacity, or efforts to obtain and understand political information (Halperin et al., 2009).
The question is what makes hate so persistent and prevalent in politics, more so than anger or fear. Hatred seems an effective, simple, political tool that is commonly used by politicians to attain ingroup solidarity and political benefits and/or outgroup exclusion. Campaign ads, canvassing, and slogans based on collective hatred are the bread and butter of successful campaigns because the message is simple and emotionally appealing (Hutchings, Valentino, Philpot, & White, 2006;Lazarsfeld, Berelson, & Gaudet, 1944). Hatred has been employed in a number of local and national political campaigns in Israel, Europe (Mudde, 2005), and the United States (Kaplan & Weinberg, 1998). The simple and extreme nature of hatred increases its recurrence in the political realm (Leader et al., 2009). The intensity, swiftness, and superficiality of current political communication in many countries enforce cues, symbols, and extreme emotions such as hatred (Galtung & Ruge, 1965;Kinder & Sears, 1985).
Notwithstanding the context of moral values, hatred may be problematic from a political perspective. From a leadership perspective, fine-tuning of the exact patterns of hatred is almost impossible; hence, hate rhetoric can backlash. On the one hand, the use of hate rhetoric may attract traditional voters, encouraging them to reconsider their typical support as they search for new paths to channel their group-based hate and opt for more extreme political representation. On the other hand, the use of hatred to mobilize new voters may enhance their support for their own traditional parties (Halperin et al., 2012).

In Conclusion
Hate is elicited in reaction to very negative transgressions by another person or group. It can be an emotional reaction to a specific event (i.e., immediate hate), but it often occurs as a sentiment (long-term emotion), generalizing from just one event to the nature of a group or person. Especially extreme transgressions may result in a plethora of negative emotions, like contempt, disgust, anger, humiliation, or revenge; and thus the question is to what extent and how hate differs from other emotions. We think that there is overlap between these negative emotions, but we can still theoretically distinguish them on the basis of unique patterns of appraisals and emotivational goals. This does not mean that daily lives are neatly carved up according to these theoretical categories, especially because these emotions may often be elicited in reaction to the same events, and thus may occur either simultaneously or sequentially. On the basis of research on interpersonal and intergroup hate, we suggest that the unique appraisals of hate are a stable, dispositional attribution of malicious intentions, in combination with the appraisal that the target is seen as dangerous and that one feels powerless (see Figure 1). The emotivational goal associated with hate is to destroy the hate target, whether physically, socially, or symbolically. This goal is associated with the aforementioned appraisals and is different from the goals of contempt (social exclusion), disgust (distancing oneself), revenge (getting even), humiliation (withdrawal), or anger (attack). Still all these emotions can occur together with hate and each of them can become associated with the sentiment hate.
From a functional perspective, hate is part of a self-defense system by attempting to eliminate the target of one's hate. In an intergroup context, one's group identity is threatened by an outgroup member, and self-defense implies defense of one's group membership. Hate seems particularly prone to spreading at this intergroup level because it helps us to defend ourselves by strengthening the ties with our ingroup and putting all the blame for insecurity and violence elsewhere. Because hate is based on the perception of a stable, malevolent disposition of the other person, haters perceive little room for constructive change, and therefore there seem only radical options left to act upon one's hate. In case of most emotions, the fulfillment of the emotivational goal reduces the emotion. For example, one may seek revenge in order to get even in suffering, and once this has been established, feelings of revenge decrease (see also Seip, Rotteveel, van Dillen, & van Dijk, 2014). In the case of hate, this means elimination of the target. This leaves the question whether hate can be changed or down-regulated. We think that this is difficult, and the only way to regulate hate would be to reappraise the malevolent intentions of the outgroup as stable and as a result of their identity or character. Trying to explain the hated target's actions in terms of circumstances rather than nature would be a first step. In the same vein, merely being angry, devoid of hate, would be a much more constructive emotion because its intensity can be decreased if the target apologizes or changes their behavior. Whether we can down-regulate hate, and how it relates to perspective taking, empathy and forgiveness are interesting and socially relevant venues for future research.

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.