A reader once sent me the following sentences and asked which was correct and why:
The research also must be validated.
The research must also be validated.
Also is like only in that both are what The Cambridge Grammar of the English Language calls “focusing modifiers”: their position in the sentence determines which element in the sentence they focus on.
Focusing modifiers can occupy several positions in the sentence, causing either ambiguity or clarity. Like real estate, also’s value is all about location; it modifies whatever is closest to it.
Let’s take the second sentence first:
The research must also be validated.
In this sentence, also is smack in the middle of the verb phrase must be validated, a legitimate place for it to be. Because it’s sitting right next to it, we know that also is modifying be validated. That is, whatever else must be done with the research, it has to be validated as well.
Now let’s look at your first sentence:
The research also must be validated.
With also outside of the verb phrase, it may be focusing on the action, as with the second sentence, or it may be focusing on research, the other word it’s snuggling up to. So, we could take the sentence to mean that something (e.g., the researcher’s credentials) must be validated and so must the research.
There are two other positions also can occupy. It can occur at the front of the sentence:
Also, the research must be validated.
That would make also a sentence adverb: whatever else must happen, the research must be validated as well.
It can also occur at the end of the sentence:
The research must be validated also.
Again, we end up with an ambiguous meaning. Also could be modifying the whole sentence, as it does when it’s at the beginning of the sentence, or it could be modifying the verb phrase and focusing on the verb, as with the second example.
Which of the examples is correct depends on the intended meaning. Take a look at the context and see which meaning is wanted.
A version of this article originally published in the December 2011–January 2012 issue of Copyediting newsletter.