I mentioned this at the end of my last post. I realize that I'm probably a bit vague in what I mean when I say "dependency." So, for what it's worth, I will attempt to clarify.
A specific reader's ability to read a particular novel is dependent on several factors within that novel (so not lack of time, or distracting surroundings, or other external factors such as these.) The novel needs to help the reader understand its contents if it wants to communicate whatever story or idea it is trying to communicate.
A few examples. Each novel needs to introduce its characters in such a way that the readers begin to get to know them. If the author assumes that we already know everything about their sassy detective before we open the book... well, let's just say we're going to have a hard time connecting with the character and understanding when he suddenly spirals down into a depression halfway through the story.
In addition, each novel needs to introduce and communicate its setting, explaining the look, feel, and/or layout of specific locations as well as the general feel of society beyond our lead character(s). Without this, we don't really care whether or not the character succeeds because we don't understand how he relates to the world around him. In addition, it makes it damned hard to figure out where or what anyone or anything is and we thus begin to feel like we're simply living inside of this character's head the entire time. Very cerebral, but also rather confusing.
Hopefully that explains a little bit of what I mean about dependency. It's this idea that you need to establish one thing before you can move on to another. And it's the novel's responsibility to help the reader understand what's going on by describing more than just a series of events. (Although, there is a certain level of dependency that applies to plot. Foreshadowing, red herrings, etc. Various tools and gadgets to track the path of our protagonist and the events surrounding him to reach a believable conclusion.)
So if you haven't taken the time to establish that Billy Joe Bob, the detective repairman, owns a gun and has had extensive training with firearms due to his service back in the Gulf War, then you can't have him go off on a rampage through the seedy underbelly of City A in his attempt to rid his neighborhood of crime. It just wouldn't be believable.
There are, of course, some things that are harder to establish than others. It's kind of difficult to prepare your readers for the introduction of a shapeshifting demon as the villain in the second act when you've spent your entire first act examining the protagonist's psychological profile with near-clinical precision. Blending science and the supernatural is always tricky.
In that case, you have to weigh your pros and cons. Maybe it'll turn out that this particular story you want to tell isn't especially telllable. I've scrapped over a dozen well-developed ideas because I decided that they simply didn't work in this medium (or, at the very least, I'm not skilled enough of a craftsman to make it work in this medium.) In other situations, you might decide that you simply need to modify the structure of your story or that the risk of losing some of your readers with a potentially ridiculous plot development is worth it for the awesomeness that you'll be able to introduce into the story because of it.
There isn't really a good answer here. But you need to make sure that you support each and every element of your story in an amount proportional to its prominence in the work. Otherwise, everything is going to fall flat as it collapses under the unsupported weight of your one undeveloped, anti-dependent story element.
It's all connected, after all.
Next time, I think I'm going to talk about how this idea of dependency applies on a larger scale.
(By the way, that story with the psych-profile and the demon actually exists. And it works. Some people are kind of thrown off by the appearance of the demon, thinking that it came out of nowhere. But the rest of the book uses it in a comprehensive-enough way that it makes up for the sudden shift to supernatural. It's called I am not a Serial Killer, by Dan Wells. Check it out. The detective repairman veteran of the Gulf War, or whatever, isn't actually in a story yet. You're welcome to use him if you'd like. Though... now that I think about it, it might be fun to write about such a ridiculous character. We'll see.)