One of the nice things about verbs is their flexibility. Different verb forms can convey a wealth of information about both the subject and object governed by the verb. Tenses, for example, give you a sense of when a verb is taking place, while moods give you a sense of whether the action is taking place on a literal or abstract level.
The simplest and most common verbal mood is the indicative mood. We use it to communicate that action is happening literally: the boy was jumping, and the man walks along the riverbank. The subjunctive mood, on the other hand, is used to discuss action that isn’t certain to happen. Sometimes, as in the phrase “if I were you,” we even use it to describe action that is almost certainly not going to happen. Subjunctive verbs can be readily identified by the helping verbs that accompany them; ‘could,’ and ‘were’ are two very common companions. Occasionally, a subjunctive verb will be found in a ‘that’ phrase, as in the sentence, “She thinks that I poisoned her son.”
There are a couple of occasions when writers need to pay special attention to subjunctive verbs. The first is when they themselves are communicating uncertain or impossible information to the reader. Here, the subjunctive mood makes it clear that the verb’s action is occurring on an abstract level.
The second occasion is when a character is speaking about information that may or may not happen. One of the most common tics in human speech is the habitual confusion of “was” and “were” when speaking in the subjunctive mood. Although an educated or genteel character is likely to ponder “what would happen if she were there,” less sophisticated characters will be more prone to talking about “what I would do if I was in your shoes.”
Subjunctive verbs can convey much more information to the reader than a simple action. They can convey whether the action is certain to happen, they can convey the character’s attitude toward the action, and they can convey the character’s level of sophistication. The informational density of the subjunctive tense is just one example of how flexible a verb can be.