In literature, nothing should ever be done for the hell of it—or because the writer thinks it looks pretty, which amounts to the same—but backed by reasoning.
Perhaps, the question to ask is: Does a chapter need a title?
The answer will depend on whether a title adds value to the chapter or not.
In The Coming Global Superstorm, by Art Bell and Whitley Strieber, after a lengthy preface we encounter a prologue and a title: The Storm Begins.
An average reader like me pauses... so what? Since the book is about a superstorm, it stands to reason it has to start somewhere. Next, we hit the first chapter and its title: Present Danger.
The book is labeled as “The stunning New York Times Bestseller,” therefore one supposes it sold well, but the question remains: Where’s the added value in those titles?
In my experience titles may add two types of value: illustrative and aesthetic.
Illustrative.
Some plots require titling the chapters by the location, date and time. It may be that the narrative is linear or restricted to confined environments. But if the action shifts between different places, giving the reader a hint of where he or she is at the start of the chapter can be helpful. In addition, the writer can push the action, instead of having to set the scene each time by weaving in the narrative, location, date, and time.
This can be particularly helpful if we open chapters with flashbacks. Unannounced by a line setting the chronology, a flashback may throw the reader into confusion; and a confused reader soon loses interest.
A short line with the time, usually set on 24-hour or military style, can be a good idea in these rare plots where the action takes place on a single day. Also, time and date could be indicated if the plot evolves over a limited period of time, say a week. In Three Days of the Condor, James Grady opens chapters with a simple date reference: Chapter 1 Wednesday.
Another excellent reason for titles is to name different narrators, in particular if the POV changes. Several writers, such as Thomas Gifford—author of The Assassini published by Bantam Books—use third person limited in alternate chapters and first person on chapters titled with the narrator’s name.
This way, illustrative titles serve to ease the reader’s experience by providing references that otherwise would have to be woven in the chapter openings.
Aesthetic.
When used well, chapter titles can make the reading experience richer, more nuanced, more complex in texture and meaning or even add a subtle ambivalence to the events that follow. This way, titles may capture a mood in a few words.
This is often accomplished with epigraphs or teasers—such as a quote pertinent to the upcoming events. These snippets can foreshadow, add layers of structure or satirical counterpoints by reference to other texts, etc.
In Harry Potter and the Philosopher’s Stone, J.K.Rowling uses chapter titles such as:
Norbert the Norwegian Ridgeback
Nicolas Flamel
The Journey from Platform Nine and Three Quarters
Nothing extraordinary in these titles but a device to make the chapter openings look pretty.
There’s a huge difference between the previous titles and those of a master, such as Charles Dickens in A Tale of Two Cites.
In Book II, the title of chapter five is "The Jackal." The jackal is the nickname given to Sydney Carton, and it holds a great symbolic meaning.
A second chapter title that exhibits symbolism is that of Book II, chapter fifteen: Knitting. In a literal sense, Madam Defarge knits a registry of those marked to be killed in the revolution.
Likewise, in Book II, chapter fourteen bears the title: The Honest Tradesman. This chapter centers on Jerry Cruncher and his activities as a self-labeled Resurrection Man. Obviously, the irony is between the honest tradesman and Jerry’s midnight excursions in which he digs up buried bodies. Dickens chapter titles disclose a very ironic and satirical humor.
I include these titles by one of literature’s sacred cows to highlight the care and insight vested in a few words. In a way these are additional writer’s gifts to his readers.
And from the sublime to the ridiculous. Some writers use chapter titles to attempt at being funny or clever. Devoted readers may adore such devices, which amount to trash disguised as silliness. A few chapter titles that come to mind are Stephenie Meyer’s in Breaking Dawn. Cross my heart, I’ve not made these up
Chapter 10. Why Didn't I Just Walk Away? Oh Right, Because I'm An Idiot.
Chapter 13. Good Thing I've Got A Strong Stomach
Chapter 15. Tick Tock Tick Tock Tick Tock
Chapter 17. What Do I Look Like? The Wizard Of Oz? You Need A Brain? You Need A Heart? Go Ahead. Take Mine. Take Everything I Have.
Finally a word of warning: Titles can be dangerous. In Harry Potter and the Philosopher’s Stone, J.K.Rowling uses as a chapter title “The Midnight Duel.” If they give too much away, titles may ruin the reading experience by clueing the reader into what is going to happen.
There’s a huge difference between the previous titles and those of a master, such as Charles Dickens in A Tale of Two Cites.