Appeal to emotion or argumentum ad passiones ("argument from passion") is a logical fallacy characterized by the manipulation of the recipient's emotions in order to win an argument, especially in the absence of factual evidence. This kind of appeal to emotion is a type of red herring and encompasses several logical fallacies, including appeal to consequences, appeal to fear, appeal to flattery, appeal to pity, appeal to ridicule, appeal to spite, and wishful thinking.
The appeal to emotion is only fallacious when the emotions that are elicited are irrelevant to evaluating the truth of the conclusion and serve to distract from rational consideration of relevant premises or information. For instance, if a student says "If I fail this paper I will lose my scholarship. It's not plagiarized" the emotions elicited by the first statement are not relevant to establishing whether the paper was plagiarized. On the other hand, "Look at the suffering children. We must do more for refugees." is not uncontroversially fallacious, because the suffering of the children and our emotional perception of the badness of suffering may be relevant to the conclusion. To be sure, the proper role for emotion in moral reasoning is a contested issue in ethics, but the charge of "appeal to emotion" often cannot be made without begging the question against theories of moral cognition that reserve a role for emotion in moral reasoning.
Appeals to emotion are intended to draw inward feelings such as fear, pity, and joy from the recipient of the information with the end goal of convincing them that the statements being presented in the fallacious argument are true or false, resp.
The power of emotions to influence judgment, including political attitudes, has been recognized since classical antiquity. Aristotle, in his treatise Rhetoric, described emotional arousal as critical to persuasion, "The orator persuades by means of his hearers, when they are roused to emotion by his speech; for the judgments we deliver are not the same when we are influenced by joy or sorrow, love or hate." Aristotle warned that emotions may give rise to beliefs where none existed, or change existing beliefs, and may enhance or decrease the strength with which a belief is held. Seneca similarly warned that "Reason herself, to whom the reins of power have been entrusted, remains mistress only so long as she is kept apart from the passions."
Centuries later. French scientist and philosopher, Blaise Pascal wrote that "People [...] arrive at their beliefs not on the basis of proof, but on the basis of what they find attractive." Baruch Spinoza characterized emotions as having the power to "make the mind inclined to think one thing rather than another." Disagreeing with Seneca the Younger that emotion destroys reason, the 18th century Scottish philosopher George Campbell argued, instead, that emotions were allies of reason, and that they aid in the assimilation of knowledge. However, Campbell warned of the malleability of emotion and the consequent risk in terms of suggestibility:
- [Emotions] are not supplanters of reason, or even rivals in her sway; they are her handmaids, by whose ministry she is enabled to usher truth into the heart, and procure it to favorable reception. As handmaids, they are liable to be seduced by sophistry in the garb of reason, and sometimes are made ignorantly to lend their aid in the introduction of falsehood.
Drawing on the social psychology of his day, propaganda theorist Edward Bernays confidently asserted that "in certain cases we can effect some change in public opinion with a fair degree of accuracy by operating a certain mechanism, just as a motorist can regulate the speed of his car by manipulating the flow of gasoline."  Bernays advised that to change the attitudes of the masses, a propagandist should target its "impulses, habits and emotions"  and make "emotional currents" work to achieve the goal.
Indeed, some contemporary writers have attributed the popularity of the most destructive political forces in modern history—from Nazism to Jihadism—to the ability of their leaders to enchant (rather than convince) publics and to oppose "the heavenly ecstasies of religious fervor" to the "naked self interest" and the icy, individualistic rationalism of modern liberalism.
Similarly, Drew Westen, professor of psychology psychiatry and behavioral sciences at Emory University, drawing on current psychiatric and psychological research to demonstrate the power of emotions in affecting political cognition and preferences, wrote that, "when reason and emotion collide, emotion invariably wins."  Westen, an advisor to Democratic political campaigns, believes that evolution has equipped people to process information via emotions and that people respond to emotional cues more than to rational arguments. Accordingly, Westen believes that emotion lies at the center of effective persuasion and that appeals to emotion will always beat appeals to reason:
- A central aspect of the art of political persuasion is creating, solidifying, and activating networks that create primarily positive feelings toward your candidate or party and negative feelings toward the opponent …
- You can slog it for those few millimeters of cerebral turf that process facts, figures and policy statements. Or you can … target different emotional states with messages designed to maximize their appeal.
A social psychology theory posits that attitudes have three components — affect, cognition and behavior. The cognitive dimension refers "to beliefs that one holds about the attitude object, and behavior has been used to describe overt actions and responses to the attitude object." Affect, meanwhile, describes "the positive and negative feelings that one holds toward an attitude object", that is, the emotional dimension of an attitude. Modern theorists have modified the tripartite theory to argue that an attitude "does not consist of these elements, but is instead a general evaluative summary of the information derived from these bases."
Political scientist George Marcus (writing with Russell Neuman and Michael Mackuen) identifies two mental systems through which reason and emotion interact in managing and processing political stimuli:
- First, the disposition system "provides people with an understanding, an emotional report card, about actions that are already in their repertoire of habits." That is, the first system is that which monitors the casual processing of political information through habit, through which most of our information processing is done.
The second system, the surveillance system, "acts to scan the environment for novelty and sudden intrusion of threat." In other words, the second system monitors the environment for any signs of threat. If a threat is found, that system takes people out of habitual, casual processing and puts them in a state of alertness and receptivity to new information:
- "what is interesting about this second emotional system is that the onset of increased anxiety stops ongoing activity and orients attention to the threatening appearance so that learning can take place. [...] when the system detects unexpected of threatening stimuli, however, it evokes increased anxiety, it interrupts ongoing activity, and it shifts attention away from the previous focus and toward the intrusive stimuli." 
Marcus further argues that "emotional engagement will motivate people toward making more deeply reasoned decisions about politics than those who remain dispassionate." Other thinkers have argued that "when an emotion is aroused and experienced, it can involve a number of psychological processes that can then be used as a platform for promoting and securing influence and compliance."
Regardless, it would stand to reason, then, that affecting a subject's emotional state, in conjunction with a political message, could affect that subject's attitudes.
In modern philosophy, there are two core appeals to emotion. One is the appeal to force (known as ad baculum) the other is the appeal to sympathy, known as ad misericordiam. These are only considered fallacies when used in doxastic systems.
Accepted wisdom[who?] is that, "[w]hen it comes to issues of emotional importance, convincing someone to change his or her existing beliefs appears to be a virtually hopeless undertaking."  And yet, manipulating emotions may hold the key to shaping attitudes:
- "[t]he use of emotions to instill beliefs is prevalent in political propaganda. Depicting individuals, groups, or issues from an emotional perspective, or as actors in emotional events, evokes emotion. It thereby slips the belief that the emotion is about into the listener's mind. Presumably, it slips the beliefs into the listener's mind more easily, smoothly and unquestioned than would happen when the information alone was transmitted." 
Though it is still an underdeveloped area of research, a number of scholars are demonstrating that manipulating emotions surrounding a persuasive message does affect that message's effectiveness. It has been shown, for example, that people tend to adjust their beliefs to fit their emotions, since feelings are treated by people as evidence, and when feelings match beliefs, that is seen as validation of the underlying beliefs. Other research shows that "emotional stimuli can influence judgment without a judge's awareness of having seen or felt anything (e.g., Bargh, 1997; Murphy & Zajonc, 1993)."
Indeed, "recent studies have confirmed that affect does play a general role in attitude change, whether due to persuasive communication, or to cognitive dissonance processes (Petty et al., 2001)."
Psychologists Petty & Cacioppo found that there are two ways of processing persuasive messages: (1) to focus on the content and quality of the message (central processing), or (2) to focus instead on external cues (such as the source of the message) and to disregard its content (peripheral processing). "When participants use the central/systematic route of responding to message content, they tend to be persuaded more by strong arguments, and less by weak arguments. However, the strength of the argument matters less when the peripheral route is chosen. In that case, other "peripheral" factors, such as the credibility of the source of the message or the intention of the communicator become important in the persuasive process." Petty and Cacioppo suggest that negative affect should lead to more central processing and positive affect to more peripheral processing. That is, "In happy moods, people tend to be persuaded equally by strong and weak arguments, whereas in sad moods, people are persuaded only by strong arguments and reject weak arguments." Said otherwise, positive moods increase the reliance on positive beliefs, whereas negative moods encourage the updating of beliefs in the light of new, significant data.
Drawing on the work of Marcus, political scientist Tom Brader says that, "by appealing to specific emotions, [communicators] can change the way citizens respond to political messages."
Influence of emotion on persuasion
Fear and anxiety
The only widely studied emotion, with respect to persuasion, is fear. Fear has been found to force individuals "to break from routine and pay close attention to the external world," including persuasive messages. Moreover, fear has been found to encourage political engagement:
- "people are demonstrably more likely to engage in the political realm when they are anxious about the candidates. Uneasiness about the available political choices leads people to pay closer attention to the political environment. [...] people learn more about the candidates (that is they acquire new and accurate knowledge) when they are anxious but not when they are enthusiastic about those candidates who dominate the political field." 
More generally, "fear is associated with both attitude and behavior change." However, "four variables that may interact to influence processing depth of a fear-inducing message: (a) type of fear (chronic vs. acute), (b) expectation of a message containing reassuring information, (c) type of behavior advocated (e.g., disease detection vs. health promotion), and (d) issue familiarity."
Guilt is the emotion that arises when an individual breaks an internalized moral, ethical or religious rule. Guilt's effect on persuasion has been only cursorily studied. Not unlike fear appeals, the literature suggests that guilt can enhance attainment of persuasive goals if evoked at moderate levels. However, messages designed to evoke high levels of guilt may instead arouse high levels of anger that may impede persuasive success.
Anger's effect on persuasion has also seldom been studied. A couple of studies, however, "suggest that a positive relationship exists between anger and attitude change." Specifically, researchers found that "anger evoked in response to issues of juvenile crime and domestic terrorism correlated with acceptance of legislative initiatives proposed to address those issues." Not unlike fear, anger was associated with close (central) information processing including of persuasive messages. At the same time, "unintentionally induced anger in response to supposed guilt and fear appeals has been shown to correlate negatively with attitudes." The persuasive uses of anger have also been studied in political campaigns, since anger can be strategically evoked by politicians to increase the motivation and engagement of their supporters, although the historian Nicole Hemmer has noted that the potential for an American candidate to use anger effectively is highly contingent on their identity.
Disgust arousal, in the context of messages opposing animal experimentation, is correlated negatively with attitude change. This is consistent with the view that disgust leads to a rejection of its source.
Empathy and compassion
A number of recent studies support the role of compassion in skewing moral judgment. The researchers' findings show there is a key relationship between moral judgment and empathic concern in particular, specifically feelings of warmth and compassion in response to someone in distress.
Images of suffering children are the ideal triggers of this instinctive compassion.
Once triggered, compassion leads individuals to favor the few they see suffering over the many who they know to be suffering but in the abstract: "People who feel similar to another person in need have been shown to experience more empathic compassion for that person than do those not manipulated to feel similar to another."
Dan Ariely notes that appeals that, through visual cues or otherwise, make us focus on specific, individual victims affect our attitudes and lead us to take action whereas, "when many people are involved, we don't. A cold calculation does not increase our concern for large problems; instead, it suppresses our compassion."
- "In many ways, it is very sad that the only effective way to get people to respond to suffering is through an emotional appeal, rather than through an objective reading of massive need. The upside is that when our emotions are awakened, we can be tremendously caring. Once we attach an individual face to suffering, we're much more willing to help, and we go far beyond what economists would expect from rational, selfish, maximizing agents."
"Little studied in the social influence context, the one clearly identifiable study of pride and persuasion considered the role of culture in response to advertising, finding that members of a collectivist culture (China) responded more favorably to a pride-based appeal, whereas members of an individualist culture (the United States) responded more favorably to an empathy-based appeal." 
Some researchers have argued that anxiety which is followed by relief leads to greater compliance to a request than fear, because the relief causes a temporary state of disorientation, leaving individuals vulnerable to suggestion. The suggestion is that relief-based persuasion is a function of less careful information processing.
- Labossiere, Michael C. "Fallacy: Appeal to Emotion". Nizkor Project. Archived from the original on 18 October 2014. Retrieved 6 November 2014.
- Aristotle, Rhetorica I, II.5.
- "The Influence of Emotions on Beliefs", Nico Frijda, Antony Manstead and Sasha Bem in Emotions and Beliefs, Cambridge University Press, 2000, p.1.
- "Beliefs through Emotions", Nico H. Frijda and Batja Mesquita in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, p.45.
- Seneca, De Ira, I, viii.1.
- Blaise Pascal, "On the Art of Persuasion," 1658.
- George Campbell, 1776, cited by James Price Dillar and Anneloes Meijnders in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.309.
- Edward Bernays, Propaganda, 1928, 2005 ed., p.72.
- Edward Bernays, Propaganda, 1928, 2005 ed., p.73.
- Edward Bernays, Propaganda, 1928, 2005 ed., p.77.
- Barry A. Sanders, American Avatar: The United States in the Global Imagination, (Washington, D.C.: Potomac Books, 2011), pp. 102,115.
- Drew Westen, The Political Brain, Public Affairs Books, 2007, p. 35
- Drew Westen, The Political Brain, Public Affairs Books, 2007, pp. 85, 88
- This theory is known as the "tripartite theory." For a summary of the theory and a list of its developers, see, e.g., Leandre Fabrigar, Tara MacDonald and Duane Wegener, "The Structure of Attitudes" in Dolores Albarracin et al., The Handbook of Attitudes, Lawrence Erlbaum Associates, Publishers, 2005, p.82.
- Leandre Fabrigar, Tara MacDonald and Duane Wegener, "The Structure of Attitudes" in Dolores Albarracin et al., The Handbook of Attitudes, Lawrence Erlbaum Associates, Publishers, 2005, p.82., citing Cacioppo et al., 1989; Crites, Fabrigar,& Petty, 1994; Zanna & Rempel, 1988
- George Marcus, Russell Neuman and Michael Mackuen, Affective Intelligence and Political Judgment, University of Chicago Press, 2000, p.9.
- George Marcus, Russell Neuman and Michael Mackuen, Affective Intelligence and Political Judgment, University of Chicago Press, 2000, p.10.
- George Marcus, Russell Neuman and Michael Mackuen, Affective Intelligence and Political Judgment, University of Chicago Press, 2000, pp.10-11.
- George Marcus, Russell Neuman and Michael Mackuen, Affective Intelligence and Political Judgment, University of Chicago Press, 2000, p.95, see also p.129.
- Anthony R. Pratkanis, "Social Influence Analysis: An Index of Tactics" in "The Science of Social Influence," A. Pratkanis, ed., Psychology Press, 2007, p.149
- Hansen, Hans (September 26, 2019). Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University – via Stanford Encyclopedia of Philosophy.
- "The Influence of Emotions on Beliefs", Nico Frijda, Antony Manstead and Sasha Bem in Emotions and Beliefs, Cambridge University Press, 2000, p.3.
- "Beliefs through Emotions", Nico H. Frijda and Batja Mesquita in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, p.47.
- "Feeling is believing: Some affective influences on belief", Gerald L. Clore and Karen Gasper in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, pp.25,26.
- "Feeling is believing: Some affective influences on belief", Gerald L. Clore and Karen Gasper in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, p.13.
- Joseph P. Forgas, "The Role Of Affect In Attitudes And Attitude Change," in Attitudes and Attitude Change, William Crano & Radmila Prislin, Ed, Psychology Press, 2008, p.145.
- "The Influence of Affect on Attitude, Gerald Clore and Simone Schnall, in Dolores Albarracin et al., The Handbook of Attitudes, Lawrence Erlbaum Associates, Publishers, 2005, pp. 465-471
- Klaus Fiedler and Herbert Bless, "The formation of beliefs at the interface of affective and cognitive processes," in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, p.165
- Ted Brader, Campaigning for Hearts and Minds," University of Chicago Press, 2006, p.18
- George Marcus, Russell Neuman and Michael Mackuen, Affective Intelligence and Political Judgment, University of Chicago Press, 2000, p.128.
- Robin L. Nabi, "Discrete Emotions and Persuasion," in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.292.
- Robin L. Nabi, "Discrete Emotions and Persuasion," in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.293.
- Hemmer, Nicole (7 March 2020). "Only one kind of anger counts in the 2020 race". CNN. Retrieved 18 July 2020.
- Robin L. Nabi, "Discrete Emotions and Persuasion," in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.294.
- http://www.bc.edu/content/bc/offices/pubaf/news/2013-may-jun/empathy-a-key-factor-in-moral-judgment.html Archived 2014-06-25 at the Wayback Machine citing PLoS One. 2013; 8(4): e60418. Published online 2013 April 4. doi:10.1371/journal.pone.0060418 PMC 3617220 Ezequiel Gleichgerrcht and Liane Young.
- [(Psychol. Bull. 2010, supra, at 15-16. In fact, we will favor those we see as being in distress even to the detriment of more numerous but faceless potential victims. See also http://www.wjh.harvard.edu/~jgreene/GreeneWJH/Greene-CogNeuroIV-09.pdf.) ]
- Margaret S. Clark and Ian Brissette, "Relationship beliefs and emotion: Reciprocal effects," in Emotions and Beliefs, N. Frijda, A. Manstead and S. Bem, ed., Cambridge University Press, 2000, p.220.
- Dan Ariely, "The Irrational Bundle". iBooks. "Archived copy". Archived from the original on 2014-12-30. Retrieved 2014-11-28.CS1 maint: archived copy as title (link) Dan Ariely. "The Irrational Bundle", p.755
- Dan Ariely, "The Irrational Bundle". iBooks. "Archived copy". Archived from the original on 2014-12-30. Retrieved 2014-11-28.CS1 maint: archived copy as title (link) Dan Ariely. "The Irrational Bundle", p.764
- Robin L. Nabi, "Discrete Emotions and Persuasion," in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.296.
- Robin L. Nabi, "Discrete Emotions and Persuasion," in "Persuasion and the Structure of Affect", The Persuasion Handbook, Sage Publishing, p.297.