The most common grammar mistake involves the ability to count. Fortunately, you only have to be able to count higher than 1.
If I write, “A man buys a house,” you can count the number of men: 1.
If I write, “Men buy houses,” you need to count higher than 1 because this sentence describes more than 1 man.
Now, let’s look at these two samples more carefully.
In the first sentence, “A man buys a house,” the subject is 1 man, described as “a man.” The verb “buys” ends with the letter “s.” When we conjugate verbs in the present tense, we can see that verbs for the third person singular end with the letter “s.”
First person, singular subject: “I buy.”
Second person, singular subject: “You buy.”
Third person, singular subject: “He buys.” (Notice the “s” at the end of the verb. It will be important in a moment.)
What we have just learned is that if the subject is singular, the verb is also singular, meaning only one person or thing. Also, we see that the verb has an “s.”
In the second sentence, “Men buy houses,” we have more than 1 man, described as “men.” The subject is plural (more than 1), and the verb no longer has the “s.”
And this is where we get the most common grammar mistake. The most common grammar mistake is to use a singular subject (one person or thing) with a verb in the third person singular (the verb has the “s”) but then refer to the subject with a plural pronoun.
Perhaps an example will help here. Let’s build a sentence part by part, and see what is happening.
Start of incorrect sentence: “Everyone” – This is 1 person because it refers to each individual person, so it is singular.
Continuing incorrect sentence: “Everyone needs” – We added the third person singular verb, which has an “s.”
Ending incorrect sentence: “to spend their money wisely.” –The pronoun in this part is “their,” and it refers to the subject, “Everyone.” “Their” is a plural subject, which means it refers to more than 1 person.
Here is the complete sentence with the grammar mistake: “Everyone needs to spend their money wisely.” This sentence has a singular subject, a singular verb, and a plural pronoun. The problem is the pronoun.
For correct grammar, the pronoun needs to be plural or singular depending on the word it refers to. If it refers to a singular person or thing, it needs to be singular. If it refers to more than one person or thing, it, too, needs to be plural.
The correct pronoun that can refer to “everyone” in this sample are “his,” “her,” “its,” and “whose.” These are all singular pronouns because they refer to 1 person or thing.
This morning, I was reading one of my favorite blogs, The Motley Fool, and I came across this sentence: “Third, for someone who wants to maximize their time…” (http://www.fool.com/investing/general/2014/01/05/should-you-start-buying-stocks-in-2014-heres-what.aspx). Whoops, it contains the most common grammar error.
The faulty sentence contains a singular subject, “who.” We know “who” is singular because it refers to “someone,” which is singular. We also know it is singular because it has a singular verb: “wants.” The verb ends in “s,” so it is third person singular.
Thus, the sentence has a singular subject and a singular verb. Then we see the pronoun “their.” The pronoun is not singular; it refers to more than 1 person. And this is the most common grammar error.
To refer to the singular subject, the pronoun needs to be singular, too. If we only change the pronoun to correct this sentence, we get these options.
“Third, for someone who wants to maximize his time…” (This is correct, but some people think using “his” is sexist, so this isn’t a good option.)
“Third, for someone who wants to maximize her time…” (Same problem as the previous correction.)
“Third, for someone who wants to maximize its time…” (This doesn’t make sense. We don’t use “its” to refer to people.)
“Third, for someone who wants to maximize whose time…” (This also doesn’t make sense.)
So what are we to do? Correcting the grammar error is simple.
If we want to use a plural pronoun, we need to have a plural subject and verb. Thus, we can change “someone” to “people” and change “wants” to “want.” Here is the correct sentence:
“Third, for people who want to maximize their time….”
Now, the subject “who” is plural. We know it is plural because it refers to the “people.” “People” is plural because it describes more than one person. We also know it is plural because its verb is “want,” which no longer contains the “s.”
A plural pronoun (“their”) can only refer to a plural subject (“who”) that has a plural verb (“want”). Now that we have a plural subject and a plural pronoun, the sentence is correct.
Here’s the advice: if you use a plural pronoun, such as “they,” “their,” and “them,” check the word it refers to. If the pronoun refers to more than 1 thing, it is correct. If it refers to 1 thing, the pronoun is incorrect, and you have made the most common grammar error.
You can fix this error two ways:
1. Make the pronoun singular (“Third, for someone who wants to maximize his time…”) or
2. Change the word the pronoun refers to so that the pronoun refers to more than one thing (“Third, for people who want to maximize their time….”)
The writing guide “Concise Guide to Technical and Academic Writing” is a good source of information to help you understand—and fix—this and other common grammar errors.