Egerton’s Eight Species: A Tool for Thinkers

Egerton’s eight species is a remarkable tool for thinkers. By thinkers, I don’t just mean philosophers. I include analysts, writers, leaders, speakers, and anyone else who deals with ideas and concepts.

You are probably wondering what I am talking about. I am talking about a list of eight ‘species,’ or ‘categories,’ that can be applied to anything. It is a method, a tool to examine and make sense of anything that you are thinking about. It is called ‘Egerton’s eight species’ because someone by the name of Egerton came up with these eight categories.

I call them categories, but you might prefer to call them questions, since you can ask these eight questions about whatever concept you are studying. I heard about Egerton’s eight species years ago, recorded them in my journal, and regret that I can’t pinpoint the exact source – though I believe they are hundreds of years old.

The Eight Species

So, without further ado, let me introduce you to the eight species. In Egerton’s words, these are

1. DEFINITION – “What is meant by the concept”
2. CATEGORIZATION – “The different sorts, parts, types, and kinds of the subject, including how it may be subdivided”
3. CAUSES – “The causes, both final and secondary”
4. EFFECTS – “The effects, fruits, and products”
5. GENUS – “The genus, or what this is related to, and about which it is occupied”
6. PROPERTIES – “The qualities, properties, attributes, and characteristics”
7. DIFFERENCE – “That which differs from it, and what is opposed or contrary to it”
8. ILLUSTRATION – “That which illustrates it, both positively and negatively.”

The Eight Species as Questions

While these species are incredibly valuable as Egerton worded them, you might benefit from hearing them in the form of a question. These are questions that you can ask about any subject you are studying.

1. How do I define this? Aim for a clear, short, and descriptive definition of whatever concept you are studying. The specie of ‘definition’ is listed first with good reason – if you can’t define it, you will never be able to examine it carefully.
2. What are the sub-components of this? Sometimes this is simple, and sometimes it is complex. A physical machine can easily be subdivided into different parts, while a concept or idea may be tricky.
3. What causes contribute to this? This is especially good to ask when examining a historical situation. What underlying factors are responsible? What could be brought into play to recreate this?
4. What does this result in? Try to list every possible result and effect that this creates. Easier said than done!
5. What category does this concept fit into? The concept you are examining could be related to similar concepts – it fits into a specific ‘genus.’ If you are examining the French Revolution, then it would fit into the genus of ‘government overthrow/revolution.’ If you are examining love, then it fits into the genus of ‘virtue’ along with faith and hope.
6. What attributes does this concept have? Certain words or phrases probably come to mind that describe this. For example, Paul listed the attributes of love in 1 Corinthians 13.
7. What does this concept not include? Sometimes, the best way to describe something is by showing what it is not. List out the different words or phrases that are not descriptive of this concept. While it is easy to recognize the exact opposite, sometimes it is more beneficial to focus on the ‘knock-off versions’ – the things that appear similar and are easily confused with the real thing.
8. What illustrates this? No matter how exactly you describe something, it is essential to illustrate it. Take the concept of faith as an example. You may describe it perfectly, with logical and exact language. However, something is lacking until you can point to stories, anecdotes, and illustrations that clearly demonstrate faith and take it from a theoretical category to a life-changing reality.

Benefitting from the Species

The eight species – while they may sound theoretical – are intensely practical. Are you a speaker who is giving a lecture on a subject? Examine your material with the eight species. Are you a teacher? Ask these questions of your concept. Even in a discussion, people will enjoy when you ask them some of these questions to clarify what they are talking about.

The real value of these species is that they will force you to master your material. You may do a good job of presenting something, while hiding your own ignorance. Force yourself to think through these eight species. It will reveal the blind spots in your understanding and lead you to mastery of the subject.

Can you think of other ‘species’ to add to this list?

How could you practically use these eight species yourself?