Classification is the process of breaking up large groups into smaller ones.
Depending upon the nature of the subject and the author’s purpose in dealing with it, the classification will be either formal or informal.
Formal classifications are both logical and complete; they are quite common in scientific literature. For example, the classification of the “marsupials of Australia” would presumably attempt to be exhaustive, omitting no known family, genus, or species in that order of pouched mammals. Formal classifications divide, subdivide, sub-subdivide, and so on, as long as the resulting groups are significantly different. Thses divisions would be the four levels on an outline– the Roman numerals, the capital letters, the Arabic numerals and the small letters (I, A, 1, a).
Informal classifications are less rigorous. A classification of “popular songs” would probably confine itself to a few well-known and rather large categories, leaving out any rare types of songs and also ignoring minor differences within the groups treated.
Both formal and informal classifications are subject to the following principles:
1. Avoid self-evident classifications. (If you are talking about honor societies, don’t divide them by male, female, and co-ed societies. That’s too “duh.”)
2. If the group is unfamiliar, it should be defined or explained before the classification. Don’t explain “college freshman,” but do explain “volatile poisons.”
3. The group should be “just right,” not too large or too small. It would take months to classify a broad subject like “technological advances” and there would not be much point to dividing a topic like thumb tacks (unless you are a thumb tack manufacturer).
4. In producing an original classification, the author should make clear the basis for each stage of division and apply it consistently. Also remember, nothing can be in two different groups. (A leopard can be in the groups “large cats” and “spotted large cats” but it can’t be in the groups “large cats” and “large dogs.”)
5. In a formal classification, no class should be omitted; in an informal classification, no important class should be omitted. A discussion of “common American writing instruments” would be faulty if it included pens, pencils, crayons, and chalk, but left out computers.
Sample informal classification of detectives:
Most of the detectives one encounters in mystery fiction are of three kinds: Supersleuths, Simpletons, and Slobs. The Supersleuths were the original species of detective-story hero, deriving ultimately from Poe’s C. August Dupin. The Simpletons came next, a radical attempt to get away from the know-everything Supersleuth. Then came the Slobs, not like the average Joe because they were too uncivilized for that. Together they describe the main types of detectives in mystery writing.
The Supersleuth has been represented by such well-known characters as Sherlock Holms, Ellery Queen, Hercule Poirot, Perry Mason, and Shawn Spencer. Supersleuths are individuals of awesome intellect. They speak Japanese and Swahili fluently, compose symphonies, collect impressionistic paintings, and possess an incredible fund of knowledge–ranging from wedding customs of Outer Mongolia to the latest discoveries in biochemistry. Naturally once such a genius devotes his “little gray cells” to identifying the killer, it is only a matter of time before justice triumphs. In fact, that is the chief drawback of Supersleuth stories: the criminal is too obviously at a disadvantage and the reader (and sometimes the author) grows tired of the inevitable, “Elementary, my dear Watson.”
To get away from the Supersleuth’s boring inevitability, many writers have turned to the Simpleton detective, a class including such diverse figures as Father Brown, Miss Marple, China Bayles, and Aurora Teagarden. Simpletons are always unglamorous and perfectly ordinary people, though they are extremely gentle and unworldly. They are thoroughly uncomfortable in the presence of a bloody mystery. In fact, the reader considers the Simpleton incapable of locating his own umbrella, let alone finding a cunning criminal. But Simpletons always have a concealed streak of shrewdness, a lively curiosity, and unfailing good luck. These qualities enable them to muddle through successfully.
Though the Simpleton’s solve the mystery eventually, even when a mess is made in the process, they should not be confused with the Slobs. Slobs are the hard-boiled “private eyes” like Sam Spade, Mike Hammer, Remington Steel, and the A-Team– tough guys who move in an alcoholic haze from blonde to blonde, pausing only to pistol-whip a suspect or to kick a few teeth down his throat.
Such Slob characters are a far cry from the Supersleuth of yesteryear. They are also not the uncomplicated Simpletons, yearning to live a quiet life. Indeed, the whole development of the fictional detective may be summarized as Superman, Everyman, and Apeman.
Obviously this is an informal classification and I took advantage of its informality to add humor. You can do that (or not) as you prefer.
Remember, your classifications do not have to match mine (think Kipsigis and American categorizations of women and cows), but they do have to make sense to you and in the paper.