syllogism
What is Syllogism? Definition, Usage, and Literary Examples
Syllogism Definition
A syllogism (SILL-uh-jiz-um) is a type of deductive reasoning that presents a major premise and a minor premise to guide the reader towards a valid conclusion. Syllogisms are a component of rhetoric commonly seen in formal arguments, which means they can also be a powerful persuasive tool.
The word syllogism was first used in English in the late 14th century, deriving from the Old French silogisme, which indicated a “scholastic argument based on a formula or proof.” The word originates from the Greek syllogizesthai, which meant “bring together before the mind, conclude; think together.”
The History of the Syllogism
While the Stoic logicians also explored syllogism, Aristotle’s theories on the topic have most influenced Western philosophical thought. In Prior Analytics (350 BCE), his treatise on deductive reasoning, Aristotle presented syllogisms as an essential tool for understanding―particularly as a rhetorical device directed towards knowledge and truth. He focused on categorical syllogisms, which rely on simple declarative sentences and deductive reasoning.
Medieval theorists, such as Boethius, Peter Abelard, and John Buridan, continued to promote the Aristotelian syllogism as an effective rhetorical tool. Important modern logicians and philosophers, such as Francis Bacon, Immanuel Kant, and George Boole, have also explored Aristotelian syllogism in their work.
The Structure of the Syllogism
Syllogisms are a form of deductive reasoning that follows a three-part structure.
- Major premise: The first part of a syllogism is a general statement; for example, “All cats are mammals.”
- Minor premise: This is a specific statement building on an aspect of the major premise; for example, “Willow is a cat.”
- Conclusion: The conclusion is reached through deductive logic based on the information presented in the major and minor premises; for example, “Willow is a mammal.”
Based on this construction, this example of syllogism is “All cats are mammals. Willow is a cat. (Therefore) Willow is a mammal.” This three-part structure allows a clear linear progression of information that leads directly to the deduced conclusion.
Syllogism vs. Enthymeme
Although syllogisms and enthymemes are related, they aren’t exactly the same. Instead, an enthymeme is a compressed version of a syllogism.
Syllogisms utilize a three-part structure of major premise, minor premise, and valid conclusion. Enthymemes omit at least one part of the premise, leaving that information implied rather than explicitly stated. That doesn’t mean the conclusion will be incorrect; however, it does mean that one part of the logical progression of information is missing.
To illustrate this idea, let’s return to the cat syllogism:
- “All cats are mammals.” (This is the major premise.)
- “Willow is a cat.” (This is the minor premise.)
- “Therefore, Willow is a mammal.” (This is the conclusion.)
If you remove the major premise, we’re left with the enthymeme: “Willow is a cat; therefore, Willow is a mammal.” By removing the minor premise, we’re left with “All cats are mammals; therefore, Willow is a mammal.”
Both enthymemes are factually correct; however, they’re not presenting the full linear progression of logic and information expressed by the syllogism’s three-part structure.
Syllogism Fallacy
Despite the logical strength of the structure, syllogisms can be used to form strange and incorrect conclusions.
For example:
- “Clowns have curly red hair.” (This is the major premise.)
- “Little Orphan Annie has curly red hair.” (This is the minor premise.)
- “Therefore, Little Orphan Annie is a clown.” (This is the conclusion.)
This is a false conclusion. The syllogism doesn’t account for all the people with curly red hair who aren’t clowns. A syllogism that presents an incorrect conclusion such as this is called a syllogism fallacy. These can be used for comedic effect; however, they’re often simply unintended mistakes in logic.
Examples of Syllogism in Literature
1. Andrew Marvell, “To His Coy Mistress”
Like all the other metaphysical poets, Marvell uses logical reasoning within his poem to create a compelling argument―in this instance, an argument for intimacy. His poem begins with the major premise:
Had we but world enough and time,
This coyness, lady, were no crime
He follows this major premise with the minor premise that the passage of time and approaching mortality are inevitable, and therefore:
let us sport while we may
The entreaty that his mistress should succumb to his seduction is the logical conclusion of his poetic syllogism.
2. Vladimir Nabokov, Pale Fire
Nabokov’s experimental masterpiece consists of a 999-line poem by fictional poet John Shade. The poem also includes notations from fictional editor John Kinbote, which proport to explain the poem while helping readers piece together the poem’s narrative, as well as Kinbote’s own story. Lines 213-214 of Shade’s poem read:
A syllogism: other men die; but I
Am not another; therefore I’ll not die.
This poetic syllogism is, of course, a syllogism fallacy. Even though Shade is not “another,” he is still—like all men—mortal. In fact, Shade’s character is killed after finishing the 999th line of his poem.
3. Christopher Marlowe, Dr. Faustus
In a monologue in Act 1, lines 40-47, scholarly Dr. Faustus explores the central problem of the theology of his time:
The reward of sin is death? That’s hard.
Si peccasse negamus, fallimur, et nulla est in nobis veritas.
If we say that we have no sin,
We deceive ourselves, and there’s no truth in us.
Why then belike we must sin,
And so consequently die.
Ay we must die an everlasting death.
This syllogism presents the idea that sin leads to death, and humans are sinful, so they must sin and thus die. Although the ultimate solution to this problem as offered by the theology of his time was to embrace Christianity and thus be redeemed from sin, Faustus uses this syllogism as a reason to bid “Divinity, adieu!” and embrace his necromantic books as “heavenly.”
Further Resources on Syllogism
Philosophy Experiment presents six rules to ascertain if a syllogism is valid or a fallacy.
The Editors of Encyclopedia Britannica composed a useful introduction to syllogistic logic.
Stanford Encyclopedia of Philosophy has a wonderful guide to Medieval Theories of the Syllogism.