Writers often fall into one of two categories: a plotter or a pantser. Let's start with a plotter. A plotter is a writer who often will pull out a stack of index cards, or a notebook, or a spreadsheet, or whatever they feel comfortable with, and plot out their story. They will meticulously define their chapters, outline their plot twists, and map out their scenes. The plotter will develop a detailed dossier on their characters, including their fears, motivations, their deepest secrets, favorite foods, hometown, and anything else that the plotter feels is relevant. Usually, a plotter will do all of this before writing a single word of the actual story.
The pantser, on the other hand, gets an idea. It may be the beginning of a story, or it might be the end. It could even possibly be both. There's even a chance the pantser might have a character name, but that might be pushing it. A pantser will get this epiphany, rush to the nearest keyboard, and start writing, flying by the seat of their pants the whole way (hence the name). They have little patience when it comes to outlining and plotting. The urge to write is too strong, or they may just not be all that organized. It just depends.
Both methods have their advantages and disadvantages. A plotter knows where they're going to start, and where they're going to end, as well as how to get there. They know their characters, almost better than they know their own family. There are no surprises for the plotter. However, as the writing process is evolutionary, sometimes plotters can plot themselves into a corner,finding it difficult to deal with that evolutionary process if it takes them outside of their defined map.
The pantser doesn't have that restriction. They're free to allow their story to evolve as they go. Just as with a reader, the story unfolds before the writer's eyes with the turning of each page. The pantser doesn’t know what's going to happen on the next page, until they write it. However, sometimes, a pantser can find themselves in a bit of a pickle when they finish writing a scene or a chapter, and then have no idea what happens next. There's nothing more depressing to a pantser than staring at a blank screen and not know what to write.
The debate over which is better has raged on in the writing community for years to the degree where, at this year's Writers Digest Conference, they had a session that talked about how to be a "plotting pantser". Is one method right and the other wrong? Plotters and pantsers alike have graced the New York Times Bestsellers list.
I've tried both methods over the years, with varying degrees of success. And, I'm not sure if I've settled on one or the other yet. When I was writing my debut novel, SIRENS IN THE NIGHT, I plotted out each chapter ahead of time, not in great detail, but enough to know what was going to happen through the novel. By the end of the first draft, I found that I had thrown out almost a third of what I had originally plotted. SIRENS IN THE NIGHT had evolved as I wrote, taking shape in ways that I hadn't imagined. Then, somewhere during the dozen or so edits it's undergone since the first draft, it received a shiny new ending. So much for my efforts to plot out SIRENS IN THE NIGHT ahead of time.
So, to answer the question so cleverly interjected in this post's title, I believe the jury is still out, at least for me it is. As I recently told a group of high school creative writing students, you have to go with what works best for you. Trying to force one method or the other will show in your writing, and that is never good for anyone, especially the reader.