US presidential rhetoric used to be much more conversational (Clinton) but has in recent years become very divisive (Trump), and not just inaugural addresses. The former style tries to persuade, the latter to mobilise the committed (Politico 2020). This is not surprising in an age of “negative partisanship” and in a high polarized political system that favours extremist rather than centrist politics. Rhetoric has become epideictic rather than deliberative and it has shifted from logos to ethos and pathos as means of persuasion.
Aristotle defines rhetoric as speech, whether written or spoken, designed to persuade. Aristotle identifies three different modes of persuasion: logos, ethos and pathos. Logos appeals to reason, ethos to character and pathos to emotion. Rhetoric is also sometimes divided into three branches: deliberative, judicial and epideictic. Deliberative rhetoric seeks to persuade or dissuade. Judicial (or forensic) rhetoric considers whether or not something was just, legal or ethical. Epideictic rhetoric praises or blames.
Cicero lays out five canons of rhetoric, including inventio (process of developing arguments), dispositio (organising the arguments for effect), elocutio/ pronuciatio or style (putting everything into words), memoria (memorizing speech) and actio or delivery (gestures, pronunciation, tone and pace of speech).
Rhetorical devices are related to style. Who will ever forget Caesar’s Veni, Vidi, Vici (asyndetism, also tricolon) or Churchill’s Blood, Sweat and Tears (allusion)? (Though funnily enough, in the original it reads blood, toil, tears and sweat.) Style will vary depending on the context, the audience, the purpose of the speech and the speaker. The use of rhetorical devices helps make speeches more impactful and more memorable.
Delivery matters greatly. The famous 7-38-55 rule, perhaps somewhat of an urban myth, says that listeners deduce feelings, attitudes and beliefs about what someone says not so much by the actual words spoken (7%) but by a speaker’s body language (55%) and tone of voice (38%). This means that delivery is generally way more important than words. The deck is stacked against logos when it comes to persuasion. Hitler and Mussolini understood that, and Berthold Brecht made fun of it in The Resistible Rise of Arturo Ui.
The non-rational/ non-logical aspect of rhetoric and especially public speech offers speakers great opportunities to tap into an audience’s cognitive, social and affective biases. Logos is typically hopelessly outgunned. They tend to reject the views of people they dislike. They are more likely to believe somebody who is a member of their in-group. They hang on to their Bayesian priors for too long. They seem to be more likely to believe tall males with an erect posture and a deep voice than people lacking these characteristics (Economist 2014). Speech delivery matters greatly, including articulation, pronunciation and fluency as well as vocal elements such as pitch, pace, pause, tone, volume, emphasis, intonation, variation, stress, rhythm and speed. If you are skeptical, watch Trevor Noah!
Appeals to ethos and pathos are typically more powerful because by largely bypassing the prefrontal cortex, they directly tap into human biases. This may be one reason why pre-battle speeches appeal to pathos and ethos rather than logos. Shakespeare’s Henry V in his famous St. Crispin speech does not have much to say about why exactly the English are fighting the French adversary on French soil. Patton also largely avoided logos. Post-battle speeches appear to be more likely to contain elements of logos (Pericles’ Funeral Oration). Maybe this also divides along the lines of action versus reflection. But not all pre-battle speeches need to be chock-full of pathos. Ethos can be just as effective (Collins).