Of course there are many theories about conflict in storytelling. What types there are, what they are called, how best they operate, etc. But for me if just one of these three are absent, your screenplay will miss the mark. In a good script all three are interwoven and inseparable when reflecting the theme of the story.
1 LOCAL CONFLICT
The first and most obvious is the conflict that takes place between characters as they journey through the story world. It’s usually generated by a physical obstacle that has to be overcome, and therefore action related. This is usually a literal obstacle to overcome for the Protagonist; a fight, a car chase, a foot race to run, etc.
2 INNER CONFLICT
Each primary character should have an inner conflict (or two). It’s what reveals emotion and makes them interesting and three dimensional. This is the conflict that takes place inside their head of the character – their insecurities – and so these are in essence mental challenges for the character to overcome. “I’m not good enough.” “I can’t do it.” “Should I go or should I stay?” Etc.
It’s not only the Protagonist and Antagonist that should have inner conflict, if the other Primary Characters also have emotional conflict it will only enhance the quality of your writing and the depth of the characters. (Beware the trap… don’t waste your time giving Minor Characters like the Check-out Girl who appears in only one scene, inner conflict.)
3 GLOBAL CONFLICT
This is often not as obvious, but is just as important. The world in which the characters find themselves should reflect both the Local and Inner conflicts on a much grander scale. This is often the World vs Something, usually a big entity vs a smaller entity, for example a community versus the government, but it could also be the world versus an environmental disaster.
WHAT MAKES CONFLICT WORK?
The answer is simpler than you think… it’s the size of the stakes! Conflict without stakes is pointless and boring. BUT the higher the stakes and the more at risk, the more tension you can generate in the story from the conflict. Three conflicts… three times the stakes… three times the tension, which is essential for both generating and holding audience interest – which should be your number one priority when writing your story.