Well, OK, on its face, that’s only one error, and a pretty simple one at that. “It’s” with an apostrophe can only mean “it is” or “it has.” The apostrophe takes the place of the missing letters in this case, just like the apostrophe in “don’t” or “can’t,” so if you are using “it’s” with an apostrophe and cannot logically replace it with either “it is” or “it has,” then the correct spelling is “its” with no apostrophe. Example:
- It’s been too long since I spent the day at the seaside.
- The maple shed its leaves assiduously throughout the fall afternoon.
But of course there's an excellent reason why “it’s” and “its” get misused by capable writers. It’s simply that the apostrophe has one other major function in English besides standing in for missing letters. The apostrophe also is used to mark the possessive case, as in “John’s books” or “the leaders' conference.” The problem, naturally, is that “its” is a possessive pronoun, so the instinct is to want to insert an apostrophe to mark possession. Pronouns are different from nouns, though. We just don’t do apostrophes in our possessive pronouns (his, her, your, their) the way we do with our nouns.
So, then, enter common error in English #2: Correctly inserting the apostrophe in a possessive noun. Here's one that I often have to stop and think about, though the basic rule is straightforward: For a singular noun, add apostrophe-s to the end to make it possessive. For a plural noun ending in “s,” add only an apostrophe to make it possessive, and for plural nouns not ending in “s” (such as children), add apostrophe-s to the end to make it possessive. Examples:
- the boss’s desk (singular noun; add apostrophe-s to form the possessive)
- the child’s bookshelf (singular noun; add apostrophe-s to form the possessive)
- a managers’ meeting (plural noun ending in “s”; add apostrophe to form the possessive)
- the men’s room (plural noun not ending in “s”; add apostrophe-s to form the possessive)
- Paul Brians’ excellent book on English usage
(singular proper noun made possessive by adding an apostrophe)
- Jacqueline du Pré’s recordings of Brahms’ cello sonatas
(two singular proper nouns—one made possessive by adding apostrophe-s; the other made possessive by adding an apostrophe)
- the Masons’ expansive collection of exotic pets
(plural proper noun made possessive by adding an apostrophe)
Fine—that’s two errors tied to “its” vs. “it’s,” but where could the third error to avoid be? It gets a bit trickier, since this is not clear-cut error-correction turf anymore, but consider these two (classic) sentences:
a) The committee reached its decision.Note, first, that “its,” not “it’s,” is the correct spelling in Example a). That's worth noting because there's my flimsy connection to the its/it’s question I'm addressing. But the issue now becomes transmogrified—it’s no longer a matter of wrestling with apostrophes and possessive forms; now it’s a question of singular vs. plural. And here, I think, is the source of much confusion among native English speakers. It all seems pretty simple when you use sentences like this:
b) The committee reached their decision.
- The dog wagged its tail.
- The cats ate their dinner.
a) The committee[, acting as a unified whole,] reached its decision.And on this point you need to settle into some comfortable in-between space that decides both can be correct. Now, enlightened, you can go forward knowing you know which one you mean when using the singular (its) or the plural (their).
b) The [members of] the committee reached their decision.
There is so much more to say about “their” and “they,” and the tradition of the “singular they,” which has been covered quite thoroughly elsewhere. For now, I’ll just take the opportunity to announce that these issues and many others are addressed concisely, accurately, and fairly in Common Errors in English Usage 2nd Edition, which—as of today—is available for ordering and will be shipping in about three weeks. Have fun!