Just like in life, there's certainly a time and place in your story where it's fine to not have much dialogue. There are a couple of dangers lurking in those non-chatty scenes that you should be aware of:
Too Much Introspection
Any scene that involves your character sitting alone, drinking chai tea, contemplating the meaning of life should instantly be cut. Or you should follow the advice of writer Erle Stanley Gardner and have someone walk in with a gun. Your choice.
I know J.D. Salinger did just fine with The Catcher in the Rye, but as a general rule, broody main characters do not work well because they don't do very much.
Are you lacking dialogue because you've spent three paragraphs detailing the room your character is in? I notice this happening most often in historical, sci-fi, and fantasy manuscripts because of how unique and important the storyworld is to the action. I know it's tempting and you want your reader to experience everything to the full capacity, but you can't sacrifice forward motion.
Rachel Hauck said something in a class once that I just loved. She said, "tell the story between the quotes." Which I take to mean that the dialogue should be progressing your story.
Try thinking of it this way: In a movie, there are no "asides." The actors can't pause their dialogue and explain things to the viewer:
"I never loved you, Robert!" The actress turns to the camera and whispers to the viewer, "Don't feel too sad; my character is being untruthful."Because when you clutter up scenes in your novel with asides like that, that's what you may as well be doing. You're sucking out the tension! Your reader has opened your book hoping to be tortured. It's weird, but true. We want the suspense. We want to be biting our nails, thinking, "Does she love him? It seems like she did, but look at how she's acting!" I mean, where's the fun in it if we're not suffering?
So close your eyes and imagine your scene as a movie where you can't simply explain your concept or explain emotions. You must communicate them through the dialogue of the actors.
As a novelist, you obviously don't have the luxury that film makers do of just being able to show the setting, and those descriptions are vital to your story, but this can be a good exercise to push you toward creative dialogue.
So you've come across a scene full of brooding and descriptions and explanations. You think there should be more dialogue. What should you do?
Make your character's talk! You're in charge!
I'm not talking about filler conversations (How are you, Bob? Fine, Susie, how are you? Oh, I'm doing fine...) I'm talking about conflict-ridden dialogue that advances the story.
You do this by giving your characters something to talk about.
- They can be talking about the plan - what should be do next? but what if the bad guys do this?
- Or their feelings - you really hurt me when you made this choice.
- Or what's happening right then - why is Fido sniffing around the garden like that?
Or other things I'm probably forgetting. If they don't have anything interesting to talk about, that's a different problem relating to character development.
Also, don't leave your character alone too long. There's a time and place to ignore this suggestion, I'm sure. I was kinda shocked in the Twilight Saga when Stephenie Meyer chose to write out (what felt like) all 3 days of Bella's transformation. I thought it really dragged, and I'm not just saying that because Jacob rules.
Hopefully this makes sense. Honestly, it was kind of a tough post to write because I tend to have too much dialogue in my first drafts. If anyone has other suggestions for editing scenes with too little dialogue, please leave a comment!
Have a great weekend, guys!
Other posts you might find helpful:
A checklist for editing dialogue
Tips for improving your dialogue
Characters' internal and external motivations
Developing Secondary Characters