I personally like both the answer that's given in many writing classes, which tends toward the thousands, maybe millions of possibilities, or Aristotle's answer, which is two, one that begins with good fortune and ends in bad fortune versus one that begins with bad fortune and ends with good fortune. Why? Because I believe that plot and character are intertwined in any good story. A good writer can take the same plot, use different characters, and end up with a completely different result according to what the characters would do and why they do it.
Does it really really matter whether the plot elements of two stories are the same? Look at King Lear and Jane Smiley's A Thousand Acres. Or Romeo and Juliet and West Side Story. Or something even more basic: take the fable of the tortoise and the hare, and switch it up with a cheetah and an eland (the slowest antelope). The cheetah can run at speeds between 70 and 75 mph, but it can't keep that up very long and has to rest after sprinting to lower its body temperature. The eland is slow, but it can trot almost indefinitely. The outcome of such a race would probably be the same as the race between the tortoise and the hare. But the key to plot--again back to Aristotle--is cause and effect. And now the two stories suddenly look a little different. Slow and steady may still win the race, but the cause of the cheetah losing is a physical limitation instead of hubris.
At this point, the writer in me takes over. What if the cheetah really wants to win? What can he do to make it possible to keep going instead of stopping to rest? What would the eland do if she knows the cheetah can't keep up? (Cheetah's only hunt successfully 50% of the time anyway.) What if the eland is hungry and far ahead? Would she stop to eat?
In 20 Master Plots and How to Build Them, Ronald Tobias presented a list of lowest common denominators for sound plotting.
- Make tension fuel your plot.
- Create tension through opposition.
- Make tension grow as opposition increases.
- Make change the point of your story.
- When something happens, make sure it's important.
- Make the causal look casual.
- Don't rely on luck.
- Make sure your central character performs the central action of the climax.
So many possibilities, so little writing time....
Here's a quick tool from Read, Write, Think. Teachers use it in the classroom to teach kids how to plot, but it's a quick way to help organize a plot by looking at the basic elements against the classic plot pyramid.
Here's another link to a list of picture books that illustrate four kinds of character-based conflict (character vs. character, character vs. nature, character vs. society, character vs. self).
And here's my old stand-by, the complications worksheet:
20 Master Plots and How to Build Them by Ronald Tobias
Plot & Structure by James Scott Bell
Blockbuster Plots: Pure & Simple by Martha Alderson