novel - How does External Conflict set up the Climax?

Note: As with any aspect of writing, I'm sure there are those who disagree with it. If you disagree with the conclusions I've come to below, I would like to hear your thoughts. However, I would ask that you put them in comments, and leave answers for actually answering the question.

I recently asked the question, What is the Purpose of an Inner Conflict? I had no idea what I was getting myself into. @MarkBaker showed me that (in a nutshell) an inner conflict is a struggle between two choices, and the final choice is the climax. He also mentioned that external conflict is merely a device to set up that climax.

This flies in the face of how I have viewed conflict up to this point. Until now, I saw novels as having two distinct conflicts: Main Conflict, which was the external conflict, and inner conflict which was a reflection of the main conflict inside the character. Mark Baker's analysis of conflict makes sense to me, as it fits with what I know and works better than my previous view of conflict. It does however raise a question.

How does external conflict 'set up' the climax? This is a new way of seeing conflict for me, so I don't yet know how it works. However, the main reason I ask this question, is because it seems to me that there are other devices one could use to set up the climax in which the inner conflict is resolved. Why do you need to use an external conflict? When do you know you need one or not?

(The above assumes there is a single large-scale external conflict that spans the novel, plus any other side conflicts. Let me know if there are in fact only many small external conflicts.)

Answer

There are many ways of describing story structure, most of which are essentially pointing to the same thing. One of the simpler ones is that proposed by James Scott Bell which is a small elaboration on the basic three act structure. I think it may be a useful way to look at this question.

In Bell's view, Act I begins with some small disturbance in the life of the character and establishes sympathy with the character. Then events force the character through what he calls "the door of no return". Some irrevocable decision has been made or has been forced on the character and it is no longer possible for them to go back to their previous life as if nothing has happened. This is the end of Act 1.

Act 2 consists of escalating conflict leading to a second door of no return. This is the point at which the protagonist has made the hard choices and is a changed person as a result. Again there is no going back from this.

In the middle of Act 2 (Bell claims it is almost always in the dead center of a book or movie) is what he calls the mirror moment. It is the moment in which the protagonist looks in the mirror, physically or metaphorically, and has to face the decision of who they are and who they are going to have to become.

Act 3 is essentially about proving to the audience that the change has in fact taken place.

The mirror moment is clearly the moment of great internal conflict. It is where they ask themselves the fundamental questions about who they are, what they value, and what they are willing to do.

But what forces them to come to this mirror moment? No one wants to look at themselves in the mirror like that and face those tough questions. Left alone, they would not pass the first door of no return and would thus never arrive at the mirror moment. Something has to happen to force them through that door, and once through that door, something has to bring their affairs to such an impasse that they have to ask themselves these fundamental questions of self. Finally, some act is required to demonstrate the transformation that has occurred, and that is usually conflict with (and victory over or defeat by) something.

For story purpose, that can be anything, but in most cases it is going to be some form of external conflict. Either something happens to disturb the normal peace of their everyday life, or something occurs to thwart their existing ambition to change their life. Either way, it forces them through the door of no return. It forces them to face their mirror moment. And it challenges them to prove their transformation.

BTW, a more usual form of this question is to ask if a story needs an antagonist. In that case, the answer is that the source of conflict that forces the protagonist through the door of no return can be another person -- an antagonist -- but it can also be a force of nature or a life event -- the death of a child, or the onset of a disease for instance. These are still external conflicts that disturb the even tenor of the protagonists life, but they do not involve a human antagonist -- a "bad guy".