Modelling Persuasion through Misuse of Rhetorical Appeals (2022)

Abstract: It is important to understand how people use words to persuade each other. This helps understand debate, and detect persuasive narratives in regard to e.g. misinformation. While computational modelling of some aspects of persuasion has received some attention, a way to unify and describe the overall phenomenon of when persuasion becomes undesired and problematic, is missing. In this paper, we attempt to address this by proposing a taxonomy of computational persuasion. Drawing upon existing research and resources, this paper shows how to re-frame and re-organise current work into a coherent framework targeting the misuse of rhetorical appeals. As a study to validate these re-framings, we then train and evaluate models of persuasion adapted to our taxonomy. Our results show an application of our taxonomy, and we are able to detecting misuse of rhetorical appeals, finding that these are more often used in misinformative contexts than in true ones.

## introduction people are exposed to a large amount of online text that is quickly scrolled through, but which may have an inherent agenda to persuade or convince the reader. as a mitigation strategy, we hypothesise that automatic detection of persuasion in a text can help the reader navigate more critically online: like a skilled rhetorician spotting how something is trying to persuade and how an argument might be faulty @xcite . with this social motivation, we study how to computational model persuasion in text. computational modelling of persuasion techniques and strategies is a raising field in the area of computational argumentation. we establish the working term 'undesired persuasion' to be when the execution of persuasion in a text is 1 https://www.mvrhs.org/englishdept/shark/ links/general%20information/rhetorical% 20fallacies%20u.%20texas%20@%20austin.pdf ## computational persuasion this section sets the background of computational modelling of persuasion. we first outline the broad spectrum of different ways of understanding and modelling persuasion, to both map the field and to clarify concepts. from here the scope is reduced to existing classification schemes, focusing on their connections to rhetorical appeals. ## re-framing persuasion we discuss how to computationally model persuasion through the lens of a framework detecting rhetorical appeals. by this we examine whether problematic and undesired persuasion can be addressed in a more unified way by re-framing existing resources ( as we focus on problematic persuasion, we group fallacies based on whether they are making a faulty appeal to logos, ethos or pathos @xcite . examples of fallacies are presenting something as a false dilemma, making an appeal to fear or attacking the person instead of the argument. corpus labels grouped to martino et al. (2020a) black-and-white fallacy, causal oversimplification doubt, appeal to authority, name calling or labelling, flag-waving, bandwagon & reduction ad hitlerum loaded language, appeal to fear/prejudice, thoughtterminating cliché repetition, exaggeration or minimization, (mixed category: whataboutism, straw man, red herring), slogans misuse of logos misuse of ethos misuse of pathos others jin et al. (2022) intentional fallacy, faulty generalization, fallacy of relevance, deductive fallacy, false causality, fallacy of extension, false dilemma, circular claim fallacy of credibility, ad hominem appeal to emotion, ad populum equivocation misuse of logos misuse of ethos misuse of pathos others habernal et al. (2017) red herring, hasty generalisation irrelevant authority appeal to emotion misuse of logos misuse of ethos misuse of pathos zhang et al. (2018) personal attack misuse of ethos sheng et al. (2020) ad hominem misuse of ethos habernal et al. (2018) ad hominem misuse of ethos in the following, the grouping is discussed, starting with ethos. misuse of ethos ethos is an instrument of persuasion by appealing to credibility or authority. the fallacy of ethos is to unjustly strengthen one's own or associate's character or credibility, or to unfairly undermine or attack the opponent's character or credibility @xcite . from the previous resources listed in the fallacy of flag-waving is a corner case, as it can both be an attempt to call upon authority in the form of a country, or disparages another country, while, on the other hand, it could also relate to pathos e.g. with an appeal to the emotion of national feeling. lastly, we consider ad hominem, which is to make a personal attack. the annotation of ad hominem fallacy or personal attack category might be a source of noise, since it might target rude behaviour in general and not specific attacks on credibility. examples of positive cases tagged with the ad hominem fallacy that contain a faulty appeal to ethos: fine be that way, just to let you know you are very rude and so only falun gong practitioners are allowed to edit on this board is that right?, and one example where it is rude but where it does not attack credibility directly: the article clearly sucks @xcite . misuse of pathos pathos is an instrument of persuasion by appealing to emotion in the audience. to misuse it is to use it excessively or unfairly, e.g. creating strong positive emotions for one's stand or negative emotions associated with the opponent's argument @xcite . in the resources listed in some positive examples from existing resources: because if this crisis continues, many people will go to hell, appeal to fear / prejudice @xcite and how could someone oppress our women? they are our mothers, our lovers, our everything.. nobody would be so cruel, appeal to emotion @xcite , and "everyone is wearing the new skinny jeans from american eagle. are you?" ad populum @xcite . misuse of logos logos is concerned with the nature of the argument itself. it appeals to logic by following valid reasoning and presenting of evidence. in this regard, a misuse of logos is to use faulty logic by e.g drawing a conclusion that is not supported by the premise. in that sense, this category is distinct from pathos and ethos which are in its definitions drawing attention away from the argument itself. an example is the fallacy of red herring which is to present irrelevant or misleading information to avoid the real issue @xcite -this could often be the case by using an emotional appeal and it could therefore be grouped as a fallacy of pathos foot_1 and not logos. nevertheless, we map it as logos along with the following fallacies from the previous resources in one example of red herring that uses faulty logos: you might be correct. the best era for european economy was 60s and 70s when there were practically no immigrants @xcite . ## detecting rhetorical appeals this section relates experiments on detecting misuse of rhetorical appeals. we develop models for detecting misuse of ethos, pathos and logos in english, based on the re-framing of existing resources discussed in section 3. we then examine how misuse of rhetorical appeals links to misinformation. we understand misinformation as the working-definition from guess and lyons (2020): as constituting a claim that contradicts or distorts common understandings of verifiable facts. we posit the following hypotheses: first, we hypothesise that misuse of rhetorical appeals appears more often in losing argumentssince a faulty argument only has a persuasive effect if it is not spotted, cf. section 1. the second hypothesis is that in misinformation, not only incorrect information but also persuasive language are used, and so misuse of rhetorical appeals may appear more frequently in misinformative contexts. in the following, we present training details on the machine learning models we develop, describe the datasets we experiment on along with results, and discuss limitations and uncertainties. ## societal impact it is said we live in an information age; even who director-general tedros adhanom ghebreyesus has called the covid19 epidemic an infodemic @xcite . in general, people are exposed to a lot of text that has an inherent agenda of convincing, persuading, or misleading readers, seen in websites @xcite , political debates @xcite and news @xcite . in this paper, we follow the assumption that language use plays a role in how information and arguments are perceived. we already know that, for example, the stances people adopt in conversation can relief their belief in underlying claims @xcite . our vision is that automatic detection of undesired persuasion can help an online reader navigate more critically in the vast amount of information online, e.g by surfacing or flagging such text. this relates to the discussion that a person skilled in rhetoric posits the competences to spot how and when a text is persuasive @xcite . at the same time, automatic analysis of misuse of rhetorical appeals could help a writer present stronger more convincing arguments. as an example, one qualitative study manually analysed the rhetorical tactics and appeals used in vaccine discussion in the new york times comments @xcite . in the study, they categorised the arguments in pro-vaccines and anti-vaccines and analyzed the rhetorical tactics and appeals in the comments. they found that pro-vaccine comments more often contained ad hominem arguments, and that this was an ineffective strategy. while this comes with a dual-use risk -technology for highlighting manipulation can e.g. help manipulative authors better hide their intent -we posit that putting computational power behind rhetorical analysis can have a positive impact on the information society. ## conclusion in this paper, we unify the modelling on problematic persuasion by using rhetorical appealsor rather misuse of these. we focus on the problematic use of rhetorical appeals and re-frame and re-organise existing resources into this taxonomy. however, it is relevant to spot rhetorical appeals in all kinds of persuasion, and we speculate that for future work it might be useful to model pathos and ethos with less the distinction of misuse. we link misuse of rhetorical appeals to misinformation. we showed that misuse of appeals appeared more often around misinformation than true claims. however, we also saw that in some contexts, reliable news was frequently tagged with misuse of ethos and pathos. this indicates the relevance of assessing the use of persuasion in a broad spectrum of text.