35. Logic, Rhetoric, and Argumentation in Philosophy

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Lecture Notes

Main Topics #

The Distinction Between Logic and Calculation #

Berquist begins by clarifying that logic is not calculation or counting. Understanding what something is (essence) does not tell us how many or how much exists. These are distinct operations: definition answers “what is it?” while quantification answers “how many?” Though there is a likeness between logical and mathematical operations, they cannot be reduced to one art. Logic is not mechanical but requires genuine thinking.

The Four Forms of Argumentation #

Berquist organizes argumentation into four types, which can be classified in two ways:

Classification by Likeness:

• Syllogism (universal, necessary conclusion)
• Enthymeme (imperfect or rhetorical syllogism)
• Induction (from particulars to universal)
• Example (imperfect or rhetorical induction)

The enthymeme resembles the syllogism as a puppy resembles a dog—it has the same form but in imperfect realization. Similarly, example resembles induction but is weakened by its particularity.

Classification by Usefulness:

• For universal conclusions: Syllogism and induction (used in dialectic and philosophy)
• For particular conclusions: Enthymeme and example (used in rhetoric and persuasion about human affairs)

Berquist illustrates this with the analogy of forks and knives at a table: when organized by likeness, forks go with forks and knives with knives. But when cutting steak (usefulness), you grab both fork and knife together, despite their difference.

The Enthymeme as Rhetorical Syllogism #

The enthymeme is called a rhetorical syllogism (συλλογισμὸς ῥητορικός) because it proceeds from premises that are not strictly universal or necessary. Instead of true universality, it works from probability or likelihood (ἐνθύμημα - “in the mind”). Example: “He’s a boy, therefore he acts like a boy” works from the general opinion “boys will be boys,” but this is not necessarily true—boys can act with maturity beyond their years.

Aristotle sometimes identifies the enthymeme with syllogism and sometimes distinguishes it, depending on whether one emphasizes likeness or difference in kind.

The Example as Rhetorical Induction #

Examples function as imperfect inductions. They proceed from one or a few particulars to a general conclusion, but without the necessity that true induction requires. When recommending a restaurant based on one good meal, one implicitly assumes that meal is representative of the restaurant’s typical quality. This is weakened induction because individual meals are not identical across time.

Aristotle identifies three kinds of examples in rhetoric:

1. Historic examples - actual historical cases
2. Invented examples - hypothetical cases with proportion (ἀναλογία)
3. Fables - exemplary narratives like those of Aesop

The Practical Application: Rhetoric and Persuasion #

Rhetoric uses enthymeme and example because its purpose is to persuade about particular cases and human affairs, not to establish universal truths. In political rhetoric, example is more common (reasoning about future policy from past precedents). In courtroom rhetoric, enthymeme is more common (reasoning about particular guilt or innocence).

Rhetoric is an offshoot not only of logic but of ethics and psychology, as it aims to move emotions and project an image of credibility (ἦθος) alongside logical argument.

Key Arguments #

Shakespeare’s Othello as an Extended Example #

Berquist uses Iago’s manipulation of Othello as a detailed case study in rhetorical argumentation:

• Example used by Iago: “Desdemona deceived her father by running off with you without his permission. Therefore, she may deceive you with another man.” This uses the parallel of deception to suggest likelihood.

• Enthymeme from likelihood: Iago appeals to the opinion that Venetian women are naturally prone to deception and infidelity. He relies on Othello’s jealousy and ignorance to make weak proofs seem conclusive.

• The handkerchief as sign: The handkerchief serves as a weak sign of infidelity but becomes persuasive because Othello’s emotional state (jealousy) has already disposed him to belief. As Iago says, a jealous man will take even the weakest proofs as holy writ.

• Building ethos: Iago’s persuasion works through projecting himself as a man of integrity, understanding, and cautious wisdom—someone who sees into people’s hearts and has Othello’s good in mind.

Aesop’s Fable of the Hedgehog #

Berquist recounts Aesop’s defense of a corrupt official. The fable: a hedgehog trapped between rocks begins bleeding. Flies come to drink the blood. A smaller animal offers to chase them away, but the hedgehog refuses, saying the flies are already full—chasing them away will only bring new, hungry flies. The application: the corrupt official, though he has taken much, is at least satisfied; replacing him will only bring a new official who will take more.

This is a fable (mythical example) used as argument, though its persuasive power comes more from its narrative vividness than from strict logical force.

The Problem of False Imagination #

Berquist introduces the theme that false imagination is a major source of deception in human knowledge. People imagine things to be different from what they are:

• C.S. Lewis’s example: Arriving at a part of England he had never visited, Lewis was struck that the place was entirely different from his imagination of it. What right had he to imagine it as he did?

• Stepmothers and fairy tales: Children form false ideas of stepmothers based on fairy tales (Cinderella, Snow White) in which stepmothers are cruel and evil. These imaginative representations shape expectations about real stepmothers.

• Movies and false representation: During World War II, Hollywood produced movies misrepresenting Soviet society as free and religious to make Americans sympathetic to the Soviet government. The representational power of film creates false imagination.

• Imagination of future experience: Berquist reflects that his imagination of college (when in high school), of graduate school (when in college), and of faculty life (when in graduate school) never matched reality. People consistently imagine things differently from how they actually are.

The Role of Imagination in Representation #

Thomas Aquinas teaches: Poete est in vitere et aliquod virtuosa per superrepresentationem - “It belongs to the poet to lead us into something virtuous through super-representation.” But representation can also distort: a food becomes abominable if represented under the likeness of something disagreeable. Berquist’s example: as a boy, after taking milk of magnesia, he began to hate milk because he came to imagine milk under the likeness of that disgusting medicinal substance.

The imagination works through likeness (similitude), and false imagination creates false likeness, which then moves emotions and judgments.

Important Definitions #

Syllogism (Aristotelian) #

A form of reasoning with universal premises and a necessary conclusion. The syllogism requires true universality in its premises, distinguishing it from the enthymeme.

Enthymeme (ἐνθύμημα) #

A rhetorical argument resembling a syllogism but proceeding from likely premises rather than necessary ones. The word comes from ἐν (in) and θυμός (mind), indicating something held in the mind as opinion rather than strict knowledge. Aristotle sometimes calls it a “rhetorical syllogism” (συλλογισμὸς ῥητορικός).

Induction (ἐπαγωγή) #

An argument proceeding from many particular cases to a universal conclusion. True induction establishes universal knowledge and is used in philosophical inquiry.

Example (παράδειγμα) #

A rhetorical argument from one or few particular cases to a likely conclusion about other similar cases. Aristotle calls it a “rhetorical induction” because it resembles induction but lacks its necessary force. It is used to persuade about particular human affairs.

Likelihood/Probability (ἐἰκός) #

In rhetoric, a premise or conclusion that is probable or generally held to be true, even if not necessarily so. Iago’s appeals to “Venetian women are naturally prone to deception” exemplifies likelihood as a basis for rhetorical argument.

Ethos (ἦθος) #

In rhetoric, the character or credibility that a speaker projects. Aristotle notes that rhetoric persuades not only through argument but through moving emotions and through the speaker’s apparent virtue and wisdom. Iago manipulates Othello partly by projecting ethos—appearing as a man of integrity and insight.

False Imagination #

The disposition to imagine things in ways that do not correspond to reality. This imagination, especially when vivid, shapes perception and emotion, leading to false judgments and susceptibility to rhetorical manipulation.

Examples & Illustrations #

Restaurant Recommendation #

If someone asks which restaurant to visit based on one good meal you had there, you implicitly reason: “I had a wonderful meal at Restaurant A; therefore, you will have a wonderful meal there.” This is an example (imperfect induction) because you assume your particular experience is indicative of the restaurant’s character, though individual meals vary.

Jealous Man and Weak Proofs #

Iago observes that a jealous man will accept even the weakest proofs of infidelity as conclusive because his emotional state disposes him to believe. The handkerchief, which Othello had given Desdemona as a token, falls into another man’s hands. This is a weak sign, but it serves as apparent confirmation to an already-jealous mind.

College Marriage Example #

To dissuade a college student from marrying while in school, one might cite a historical example: “A sophomore I knew got married, had children, took a job, and never finished his degree.” This is persuasive as an example but not a strict logical proof, since other college students who married may have completed their degrees.

The Goose Laying Golden Eggs #

In a parable form: a goose lays a golden egg each day, bringing wealth. But someone impatient wants all the gold at once, kills the goose, and gets nothing. Applied to courtship: “Each date with this girl is like a golden egg. But wanting to have her all the time may destroy the golden quality of your time together.”

Boy and Man Classification #

When organizing by likeness (resemblance), boy goes with man and girl with woman. But when organizing by usefulness (biological reproduction), man and woman go together, not boy with man or girl with woman.

Notable Quotes #

“In the art of logic, it’s not counting, but understanding what something is.”

This establishes logic’s proper domain: definition and essence, not quantification.

“The art of calculating is kind of mechanical, right? And the art of logic, as I tell the students, is not a substitute for thinking. It’s a help to thinking, right?”

Berquist emphasizes that logic is an aid to thought, not a replacement for it.

“If you talk about the kind of argument it is, Enthomine is like the syllogism… But it’s like an imperfect… Syllogism, right? You see, syllogism secundum quid, right?”

The enthymeme is a qualified or imperfect syllogism—similar in form but different in necessity.

“Example is… like an immature… induction, right? Involves something of induction, right? So Aristotle sometimes calls the example a rhetorical induction.”

The example mirrors induction structurally but in weakened form.

“Now when we want to discuss the general question of philosophy, what do we do? We grab syllogism and induction. Okay? Now we want to persuade a fellow who is like his unfaithful and he grab infamines and examples, huh?”

This encapsulates the functional distinction: syllogism and induction for philosophy; enthymeme and example for rhetoric.

“Dull, barren, unfeeling ignorance… barren, because it has no… offspring, right? But knowledge of two numbers, right, can give rise to another number, right?”

Berquist uses Thomas Aquinas’s language to explain that true knowledge is fertile—it generates further knowledge—whereas barren ignorance produces nothing.

“He says, she deceived her father. You know, you’re doing the same thing with you, right? You know, the size idea.”

Berquist shows how Iago uses example as argument: parallel cases suggest similar conclusions.

Questions Addressed #

How do syllogism and calculation differ despite their similarity? #

Both involve relationships and rules, but calculation answers “how much?” while logic answers “what is it?” and “does this follow from that?” Neither reduces to the other, though moderns often conflate them into a single “science of signs” (signes of deductionite).

Why does Aristotle sometimes call the enthymeme a syllogism and sometimes distinguish it? #

Depending on emphasis: by likeness of form, the enthymeme is a kind of syllogism. By strict necessity, it is not a syllogism proper. The distinction depends on whether one classifies by structural resemblance or by the type of conclusion (necessary vs. probable).

How do example and induction relate? #

Example is to induction as enthymeme is to syllogism. Both are forms of analogical or partial reasoning, but induction establishes universal truths from sufficient particulars, while example merely suggests likelihood from one or a few cases.

In which contexts should we use which form of argument? #

For establishing universal truth in philosophy: syllogism and induction. For persuading about particular human affairs in rhetoric: enthymeme and example. This usefulness distinction is ultimately more practical than the likeness distinction.

How does imagination contribute to persuasion and deception? #

People constantly imagine things (places, people, experiences) before encountering them. These imaginative representations are often false and vivid, shaping emotions and expectations. Rhetoric and art can exploit this by creating compelling but false representations that move the imagination and thus emotions and judgment.

Why do weak rhetorical arguments persuade when emotions are already engaged? #

Iago notes that a jealous man will take even weak proofs as conclusive. Emotional predisposition (jealousy, hope, fear) makes the imagination vivid and plausible. The argument fits the already-formed emotional expectation, so it seems to confirm what the heart already “knows.”

Is poetic or artistic representation an argument at all? #

Berquist questions whether vivid but false imaginative representations (fairy tales, historical novels, propaganda films) constitute genuine arguments. They persuade through representation rather than reason, moving imagination and emotion. They may suggest conclusions but do not logically establish them. Yet their persuasive power is undeniable.