Scott Postma

A blog about the Great Books, the Craft of Writing, and Human Flourishing.

How’s That for Application?


Donald Trump has never taken a logic course to my knowledge; neither has Hillary Clinton or Bernie Sanders, that I’m aware of.

But I’ll get to that in a minute…

The science of human reasoning is called logic, and likely no other has contributed more immensely to the field than Aristotle, whose science of syllogistic reasoning is considered the seminal work on the subject.

Born in Stagira, Greece in 384 B.C., Aristotle studied under Plato for about 20 years until Plato’s death in 347 B.C. A few years later, in 342 B.C., Aristotle tutored Alexander the Great. Partly because of Alexander’s conquests, Aristotle’s works became the premiere foundation for further developments in logic (as well as other sub-fields of philosophy, such as theology) in Western civilization.

Believing Aristotle’s works on logic to be paramount, his students and followers collated six of his treatises on the subject into a collection titled Organon (meaning instrument or tool). Although a large portion of the Organon was lost to the Latin-speaking West until the twelfth century, it eventually became, and still remains, arguably, one of the most important and influential collections in the entire history of Western thought.

Following is a brief review of “Prior Analytics,” a treatise within the Organon that deals with the constructing of syllogisms, which, according to Aristotle, belongs to the faculty of “demonstrative science” (24a10).

By this he means he is laying out a theory of deductive reasoning, and specifically, the theory of validity in a deductive argument. For an argument to be sound, or what Aristotle calls a “demonstration,” a syllogism must be both valid and true. A complimentary work, “Posterior Analytics,” once undivided from “Prior Analytics,” deals with the truth of a deductive argument. Aristotle says, “Syllogism should be discussed before demonstration, because syllogism is the more general: the demonstration is a sort of syllogism, but not every syllogism is a demonstration” (25b29-30).

“Prior Analytics” is composed of two books, the first containing forty-six chapters, and the second, twenty-seven. In book one, Aristotle discusses the structure of syllogisms (chapters 1-26), explores the mode of discovery of arguments (chapters 27-31), and finally offers some analysis of various arguments and moods of syllogisms (chapters 32-46). In book two, he addresses the properties of syllogisms (chapters 1-15), their defects (chapters 16-21), and concludes by discussing various arguments akin to syllogisms (chapters 11-16).

Reading “Prior Analytics” is rather onerous, but defining the concepts Aristotle uses as the scaffolding for his composition is helpful. In the first chapter, he outlines several of these definitions.

A premise (sometimes called a proposition) “is a sentence affirming or denying one thing of another” (24a16). A premise can be universal, meaning it can belong to all or none of something else. It can be particular, meaning it belongs to some, or not to some, or not to all. And, it can be indefinite, meaning it does or does not belong, “without any mark to show whether it is universal or particular” (24a20).

A term is a subject or predicate of assertion where “a premiss (sic) is resolved” (24b18). Depending on the position of a term, it will be designated as the “middle” term, the “major” term, or the “minor” term.

Finally, a syllogism “is discourse in which, certain things being stated, something other than what is stated follows of necessity from their being so” (24b20).

In lay terms, the components of Aristotle’s logic can be understood thus: the first act of the mind is to apprehend meaning—to understand. The second act of the mind is make predications (or declarations) about what has been apprehended. Finally, the mind is able draw conclusions—it reasons (deductively, inductively, or fallaciously)—from two or more of the established predications, or premises. When the predications are combined with a conclusion—when a given relationship between two premises “produce[s] the consequence” (24b21), it is called a syllogism.

A famous example will help make concrete what has so far been abstract:

Premise 1: All men are mortal.
Premise 2: Socrates is a man.
Conclusion: Therefore, Socrates is mortal.

All syllogisms, Aristotle explains, fall into one of three figures depending on the position of the middle term (chapters 4-6). In the above example, a first figure syllogism, the middle term (men) is the subject of Premise 1 (the major premise). In Premise 2 (the minor premise), the middle term is the predicate. In the Conclusion, the middle term does not show up at all, but the major and minor terms do. They are linked in the conclusion by the middle term, the shared term of the two premises.

In a second figure syllogism, the middle term is the predicate of both the major and the minor premises. And, in a third figure syllogism, the middle term is the subject of both premises.

The number of possible syllogisms is infinite given the number of possible premise combinations. As previously stated, a premise can be universal (all or none), particular (some), or indefinite (without a universal or particular signifier). Further, a premise can be pure (something that is or is not), necessary (something that must be or must not be), or contingent (something that might be or might not be).

In chapters 4-22 of book one, Aristotle outlines eighteen valid structures within the three figure system he constructed (later a fourth figure was constructed that is largely reflective of the first figure). Later, in book two, he warns that “it is possible in every way to reach a true conclusion through false premises” while also deconstructing the numerous ways in which it is possible to draw defective conclusions from the same (55b3).

In Metaphysics, Aristotle made the assertion that the chief factor distinguishing human beings from animals is his ability to be rational—to use intellectual faculties for apprehension, predication, and reasoning.

Along with his other works on logic, Aristotle, in this treatise on “Prior Analytics,” laid the foundation for generations of philosophers, theologians, and logicians who would later apply, expand, and codify his work into an impressive, universal system for discovering truth and helping people think like rational human beings.

Aristotle’s work in deductive logic helped make the distinction between the rational and instinctive animals quite clear.

Thus, since in all rational people the distinction is crystal clear, and classic works like those of Aristotle are read by rational people to that end, all who want to be clearly disassociated with animals will be sure to read this classic work–maybe even this weekend–and use the logic therein to vote like a rational person.

How’s that for application?


Aristotle. “ANALYTICA PRIORA.” In The Works of Aristotle, edited by W. D. Ross, translated by A. J. Jenkinson. Vol. 1. Oxford: The Clarendon Press, 1928.

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About Scott Postma

Scott is a writer and teacher living in North Idaho. He loves teaching the Great Books, writing and blogging, and collecting more books than he'll ever read in a lifetime. You can subscribe to the tribe and follow him on Twitter, Facebook, and Google Plus.

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