Tag Archives: genus and species

The Genus & Species Tool

The purpose of classical education is to provide students with tools of learning. One of the most useful tools is the genus and species chart. I used this tool in every course I taught, including Logic, Rhetoric, Calculus, Physics, and Doctrine.

For example, when studying judicial rhetoric in Aristotle, I would follow his descriptions to construct the genus and species chart shown below, which shows the relationships between the seven causes of human actions:

Causes of actions chart

Aristotle argues that every human action is the result of one or more of these seven causes: habit, rational craving, anger, appetite (all voluntary actions – used for prosecution); chance, compulsion, nature (all involuntary actions – used for defense). This visual aid is much clearer than the wordy paragraph given in Aristotle’s Rhetoric text.

I used a similar chart in Calculus to show the arrangement between the types of elementary functions, in Physics for the various branches of physics, and in Doctrine for the “Liar, Lunatic, Lord” argument for the deity of Jesus. For example, the chart for the types of elementary functions looked like this:

When teaching this tool in Logic, one should insist on a clear dividing principle between species, to avoid species overlapping or being placed at the wrong level. In the above chart, the top dividing principle is “whether or not the action is due to oneself.” Under involuntary actions, the dividing principle between chance and necessity is “whether or not the cause is fixed and determined”; under necessity, the dividing principle between compulsion and nature is “whether it is external or internal.” Aristotle’s dividing principles between habit and craving or between anger and appetite are less clear, though the dividing principle under craving is obvious.

The Logic teacher not only presents this tool for use in other subjects, but also in teaching Logic itself. Formal Logic is the “master faculty” of the dialectic stage, and as such it not only teaches the tools of logic, but demonstrates how to use them in teaching. For example, I used the tool of genus and species in my Logic class when I taught the difference between supported  and self-supporting statements. The dividing principle is “how the truth value is determined.”

I would encourage logic teachers to use this tool often, both to present the lesson clearly and to train the students in its proper use. Logic teachers should also encourage their colleagues to use this tools for their students at this stage.


Shakespeare’s Use of the Liberal Arts: Logic

81Few4FQ9cL[1]The classical Christian school movement is seeking to revive a form of education that helped shape some the greatest minds of western civilization. But how do we know that our father’s were trained according to the Trivium? One delightful demonstration of this is William Shakespeare’s frequent and detailed use of the liberal arts of grammar, logic and rhetoric in his plays and poems,  a use thoroughly identified by Sister Miriam Joseph in her book Shakespeare’s Use of the Arts of Language. In this well-researched book, she argues that Shakespeare’s application of formal logic is evidenced in his use of definition, genus and species, syllogistic vocabulary, applied syllogisms, enthymemes, and more. Let me give some of her clearer examples. Continue reading Shakespeare’s Use of the Liberal Arts: Logic

Relating Terms from Birmingham Jail

One practical method of organizing arguments is to identify relationships between terms. Terms may be related as different parts of a whole (including different steps in a process) or as different species of a genus. In his “Letter from Birmingham Jail” Martin Luther King Jr. uses both methods of relating terms to organize and clarify his arguments. Continue reading Relating Terms from Birmingham Jail

Predicate noun in categorical form

Mr. Nance,

One question on 6A, problem #11. My son struggles getting a nominative in the predicate consistently. His current method is to repeat the subject (e.g. No bats are blind bats), which I tell him isn’t allowed (based on example), but he requests a better reason than that. (It being circular didn’t impress him, either.) Help? Continue reading Predicate noun in categorical form

Abstract Concrete

One of my favorite college-level logic texts is The Art of Reasoning by David Kelley. In the chapter on “Classification” he teaches on genus and species, where he reminds us that the genus of a term is more abstract than the term itself, and the species of a term is more concrete.

Kelley includes an exercise for the students to practice with these concepts. He gives sentences for the students to rewrite, replacing any boldface words with more abstract ones, and any italicized words with more concrete ones. I thought this was a creative approach to teaching the concepts, so I thought I would come up with a few sentences for you to try:

  1. She likes to chitchat on her phone.
  2. The airplane plummeted into a field and crashed .
  3. I studied the sublime planet through an optical device.
  4. The person stuck his head through the bars and got stuck.
  5. He brought me to the banqueting house, and his banner over me was love.

Exercises like this can help us to understand the concepts of genus and species while developing creativity in writing. Try making up some of your own!

Genus & Species Bonus

Lessons about genus and species charts often emphasize the capability of these charts to show relationships between terms (i.e. this is a kind of that). This is one benefit, but we should also note the benefit they provide in helping to develop arguments. Two classic examples should help to demonstrate this.

In C. S. Lewis’s The Lion, The Witch, and The Wardrobe, Susan and Peter are concerned with Lucy, who insists that she has gotten into the land of Narnia through a magic wardrobe. The Professor proceeds to develop an argument based off of this genus and species chart: Continue reading Genus & Species Bonus