USMC85 · Rhétorique

Introduction

Rhetoric

The art of using language effectively.

• art?
• language?
• effectiveness?
• Where is rhetoric used?

The art of using language effectively.

• to persuade rightfully or wrongfully
• to persuade honestly or seductively
• to argue with proper strong arguments
• to counter-argument

Rhetorical triangle

Rhetorical appeals

Examples

• Throughout my research, I have observed…
• It is magnificent, isn’t it? I am sure you understand.

Audience-expertise matrix

Adapt your communication based on who you’re addressing:

KEY QUESTION: What does this audience ALREADY KNOW, and what do they NEED to know?

Adaptation example (same content, different audiences):

• Public: “We built a system that keeps engines running safely”
• Managers: “Our monitoring system reduces maintenance costs by 30% and prevents failures”
• Peers: “We implemented a PID controller with adaptive gain scheduling to optimize thermal regulation”

Kairos

The right moment: the same argument convinces or fails depending on when, where and to whom it is delivered.

• adapt your appeal to the occasion, the audience and the context
• an argument is only as strong as its timing (a proposal is more persuasive when the need is felt)

Syllogism and enthymeme

• syllogism - a complete logical argument: all A are B, all B are C, therefore all A are C (see Logic for debate)
• enthymeme - a syllogism with a premise left implicit; the audience supplies it, and is therefore engaged
  • example: “This sensor is reliable: it is calibrated to the same standard as aircraft instruments.” (implied premise: that aircraft standard guarantees reliability)

Stasis - locating the crux of the debate

Four questions to find where an argument really stands:

1. fact - did it happen? does it exist?
2. definition - what is it? how should we name it?
3. quality - is it good or bad? just or unjust?
4. action / policy - what should be done?

The Toulmin model

A practical layout of an argument - useful both to build an argument and to attack one (Toulmin, 1958). The Toulmin model shows how reasoning moves from evidence (grounds) to a conclusion (claim), supported by a warrant and strengthened by backing, qualifiers, and rebuttals.

The bridge Metaphor: Think of your argument as a bridge:

• The grounds are one riverbank — the facts you start from.
• The claim is the opposite bank — where you want your reader to arrive.
• The warrant is the bridge that connects them.
• The backing strengthens the bridge’s structure.
• The qualifier shows how strong that bridge is — “probably,” “usually,” etc.
• The rebuttal is the storm that tests your bridge, and your refutation repairs it.

Example: Should I Work Out Today?

• Claim: I should work out today.
• Grounds: I’ve been sitting for hours and feel low on energy.
• Warrant: Physical activity improves energy and mood.
• Backing: Studies show even short daily workouts increase wellbeing.
• Qualifier: It’s usually better for my health to stay active.
• Rebuttal: Except when I’m exhausted or recovering from illness.

(Source: https://www.ciris.info/learningcenter/toulmins-model/)

Rhetorical canons

Canons are tools for the speaker.

1. Invention - pattern for one’s purpose
2. Arrangement - structure of the speech
3. Style - expression of an idea - plain style | middle style | grand style
4. Memory - make speech memorable
5. Delivery - gesture | expression | pacing

Figures of speech

• trope - signification - metaphor | personification | litotes | rhetorical question | oxymoron
• scheme - structure - antithesis | ellipsis | chiasmus

Examples

• “It was not bad.” Are you kidding me? A little pain never hurt anyone. This was an eloquent silence.
• “You are so…” “You forget what you want to remember, and you remember what you want to forget.”

Mode of discourses

• Description - present information
• Narration - sequence of events
• Exposition - present ideas
• Argument - persuade a viewpoint

Fallacies

Rhetoric for engineers

Engineers often need to persuade non-technical audiences. Key situations:

• Defending a design choice to stakeholders who don’t understand the technical details
• Requesting budget or resources from management focused on ROI
• Explaining risks to decision-makers who want to move fast
• Presenting research to interdisciplinary teams

The expertise gap: the more you know, the harder it is to explain simply. Fight this by:

1. Starting from what the audience already knows
2. Using analogies from their domain (not yours)
3. Focusing on impact, not implementation
4. Being ready to go deeper if asked, but not volunteering complexity

Example: Instead of “We implemented a PID controller with tuned gains”, say “We built a system that automatically adjusts to keep the temperature stable, like a thermostat but more precise.”

Ethical persuasion

Rhetoric can be used to manipulate. As engineers, you have a responsibility:

• Be honest about uncertainty - don’t present guesses as facts
• Acknowledge limitations - every solution has trade-offs
• Don’t cherry-pick data - show the full picture
• Respect the audience’s intelligence - simplify without patronizing
• Admit when you’re wrong - credibility is built on honesty, not perfection

A fallacy is an often plausible argument using false or invalid inference. Common ones to recognise - and to avoid:

• ad hominem - attacking the person instead of the argument
• straw man - distorting the opponent’s position, then attacking the distortion
• false dilemma - presenting two options as the only possibilities
• slippery slope - claiming one step inevitably leads to a disastrous chain
• appeal to authority - relying on an expert outside their field of expertise
• cherry picking - selecting only the data that supports the claim

References

Markel, M., & Selber, S. A. (2022). Technical communication (13th ed.). Bedford/St. Martin’s. https://www.macmillanlearning.com/college/us/product/technical-communication/p/1394117059

Aristotle. (2004). Rhetoric (W. R. Roberts, Trans.). Dover Publications. (Original work published ca. 330 BCE). https://classics.mit.edu/Aristotle/rhetoric.html

Toulmin, S. E. (2003). The uses of argument (Updated ed.). Cambridge University Press. https://doi.org/10.1017/CBO9780511840005 (Original work published 1958)

Heinrichs, J. (2017). Thank you for arguing: What Cicero, Shakespeare and the Simpsons can teach us about the art of persuasion (3rd ed.). Crown. https://www.penguinrandomhouse.com/books/217064/thank-you-for-arguing-third-edition-by-jay-heinrichs/9780804173452/

Corbett, E. P. J., & Connors, R. J. (1999). Classical rhetoric for the modern student (4th ed.). Oxford University Press. https://global.oup.com/ushe/product/classical-rhetoric-for-the-modern-student-9780195115420

Purdue OWL. (n.d.). Aristotle’s rhetorical situation. Purdue University. https://owl.purdue.edu/owl/general_writing/academic_writing/rhetorical_situation/aristotles_rhetorical_situation.html