Many students, and some teachers, think of language as a fixed logical structure with timeless rules. A guide such as this one that presumes to teach the "right" way to write for college may well reinforce this view of an eternal, ideal language. But such a view misunderstands what language is. Language, our species' greatest invention, is a rich, rough-and-tumble, and ever-changing mix of formal rules and informal custom. In a broad sense usage is always logical, but the logic of rhetoricians (who have traditionally tried to base all their rules for English on how Latin works) and of a living language can be quite different. Things that were once against the rules gradually win popular acceptance to the point that they become part of "standard English"; other things, once respectable English, are gradually driven into disrepute by scholarly opinion.

An example: double negatives as a way of emphasizing negation have a long history in spoken and written English stretching back to the time of Chaucer. But in the 18th century classically-oriented grammarians, aware that in Latin double negatives cancel out, applied the same rule to English: "Two negatives in English destroy one another, or are equivalent to an affirmative" (Robert Lowth, A Short Introduction to English Grammar, 1762). The grammarians have driven the poor old double negative into the gutter. It is not recommended for formal writing.

Thus there is an element of artificiality in any list of the leading mistakes in English. The list presented here will undoubtedly change over time. Apostrophes, for instance, are probably on the way out, in the judgment of most language scholars today. But they're not gone yet, and the audience for formal college English tends to be conservative. Thus the wisest course is to give your readers what they are used to in terms of usage.

And now, the Nuts and Bolts top-ten list of usage mistakes in student essays.

10. Apostrophes

Apostrophes have two functions: to show contractions (I won't) and possession (Shakespeare's tragedy). They are not used to show the plural of a noun:

Contractions are acceptable in academic writing, though since some teachers disagree you may have to adapt to different requirements. The main problem apostrophes present for students is in showing possession. The rule is simple, mostly—use an apostrophe followed by s for singular nouns, and an apostrophe alone for plurals:

Some writers use an apostrophe alone for nouns ending in s or z (as I did with species, above), especially when the next word begins with the same sound. But many teachers will mark this as wrong.

There is one case where it is preferable to use an apostrophe without an s: for multisyllabic names ending in s or z, especially those of biblical and classical origin:

9. Nouns ending in y

Nouns ending in y often produce similar confusion with regard to possession. If you want to talk about something belonging to a country, for instance, write country's, not countries.

8. Conjunction confusion

Conjunctions like and, but and for join independent clauses: I studied for hours but he never opened a book—and we both got A's. Students often use however, therefore, and thus as if they were conjunctions, too, but they are not. They're adverbs, and can't connect independent clauses—you'll still need a semicolon or period.

It's usually more graceful, however, to place however, therefore, and similar words not right at the beginning but at some convenient pause later on:

7. Infamy and notoriety

Infamous is not a fancy way of saying famous. It means quite the opposite: famously wicked or bad. Churchill was famous; Hitler was infamous.

Likewise, notoriety doesn't mean just being widely known—it means being known for being bad (though in British as opposed to American usage this distinction doesn't hold). Calling someone with a record of hefty contributions to charity "a notorious altruist" is a gaffe.

6. Cannot

One word, not two (not can not).

5. Affect and effect

Many writers confuse these two words. The common mistake is to use effect when you should use affect, typically when using it as a verb. Effect can be used as a verb, but its meaning is restricted, and is synonymous with produce:

For the sense of to have an effect upon, use affect:

4. Intents and purposes

Not intensive purposes.

3. Plural or singular

It or they
In American English, corporations and other collective entities are singular.

Criterion or criteria
The former is singular, the latter plural.

2. Principal/principle

Don't bother with that "The principal is your pal" stuff, because that's not the usage that trips students up. In terms of what causes problems, principal is an adjective meaning "foremost" or "most important," while principle is a noun meaning "fundamental law" or "guiding idea."

Here's how to remember the difference:

1. It's/its

Because apostrophes are used for possession as well as contraction, many students get confused about the distinction between it's and its. The solution here is to remember that it's is a contraction, not a possessive: It's = it is. It, like other pronouns (he, his; she, her) doesn't take an apostrophe to show possession:

Who's and whose have the same distinction:

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