Here's another thing that's just recently crystallized for me. I always knew subtext was a big deal (and not just to loyal X-Files viewers), but I couldn't quite explain it to myself. The argument all the books use -- that scenes without subtext are flat and boring -- makes sense to an extent, but I don't think it's always true. Where's the subtext in Mission: Impossible, 24, or most of the Bond films? Most scenes in all three of those are just about what they're about, but they still hold our interest. I'm sure there are other examples as well -- maybe not in the "great" movies, but certainly in plenty of solidly entertaining ones. So knowing that has made it a little harder for the whole subtext concept to really take hold.
But my sort-of epiphany came when I was working hard to uncover the themes and ideas within my current script -- figuring out what I was really getting at with this story, who these characters were and why they needed to change, and how those changes would be painful but necessary and ultimately rewarding for both them and the audience. Suddenly I had all these interesting philosophical concepts and character traits to work with, which was a blessing as far as adding depth and interest to my story, but also a burden because -- well, how do you work complex discussions of these topics into a fast-paced thriller?
And voila, there it was -- you do it in the subtext. That's what the subtext is for. It gives the writer a chance to talk about all the underlying morals, issues, questions, and so forth -- but without bringing the action of the story to a screeching halt and boring the audience. In a sense, subtext is just another layer of exposition hidden beneath the visible exposition of the plot. The plot contains information we need the reader to know, while the subtext contains information we want them to know (or think about). So, it's okay to put useful information in the subtext, but crucial information should be communicated more directly. David Lindsay-Abaire's play (and upcoming movie) Rabbit Hole centers around a married couple whose son was recently killed by a teenage driver. Since the entire plot is driven by that event, the script tells us unequivocally that it happened. On the other hand, if the plot were about the husband's infidelity, and the son's death had happened several years ago, it would probably be okay to convey that through subtext (it might even be preferable).
The reason, of course, is that plot is most important. If you're watching a movie and you can't follow the plot, you won't bother trying to decipher the subtext. But when the plot makes sense, and your brain synchs up with the story, then it can be a real joy to start looking for the themes, emotions, and other gems hidden beneath the surface.
The word "subtext" can be misleading, since it seems to refer only to words. It doesn't, though; at least not in a visual medium like film. In a screenplay, there are opportunities for subtext everywhere you look (and I do mean that literally). You can convey subtextual information through the locations in which scenes occur, the clothing your characters wear, physical action that goes on in the background, even the time of day or the weather. Alfonso Cuaron, one of my favorite directors, is an absolute master of visual subtext. The action and images in the background of Children of Men or Y Tu Mama Tambien could constitute movies of their own, but as subtext they simply enhance the experience, the mental and emotional response, produced by the films they're part of.