All posts by Daniel Foucachon

Genus and Species Charts

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:

genus and species 1

The Professor then adds, “Logic! Why don’t they teach logic in these schools?”

For a second example, consider how Aristotle in his Rhetoric uses genus and species thinking to understand the state of mind of wrongdoers:

Genus and species 2

Many more examples could be given, but this should show how genus and species charts can be used to organize our thinking in developing arguments.

An exhortation to teachers regarding formal proofs

Formal proofs are hard, like many other things worth learning!
In this video, I talk through the difficulties of formal proofs of validity, and why it’s worth enduring the hardship to learn them.

YouTube version HERE.