I have previously written about a common problem in scriptwriting. A writer uses his characters to advance the plot in a certain direction, pushing them toward actions and decisions that contradict their intelligence and personalities. Characters become ignorant, stupid, or behave contrary to their nature.
In poor writing, characters are lifeless puppets to advance the plot. In good writing, characters advance the plot in ways that are consistent with their intelligence, emotions, and situations. Their actions are logically motivated.
In Prometheus (2012), Charlie (Logan Marshall-Green) is a scientist who travels to a distant moon (in another solar system), hoping to meet an alien race that, he believes, created humanity. When the spaceship carrying him arrives, Charlie rushes out with his team to explore, despite there only being six hours of daylight left. Charlie is too eager to wait for the next day.
Charlie finds a barren terrain and what appears to be "a tomb" (Charlie's word) with several dead aliens. Returning to the ship, Charlie becomes depressed and drunk. He refuses to attend the autopsy of an alien's head, because "I didn't come for an autopsy."
Is this a scientist speaking? This is humanity's first contact with an alien species, but Charlie prefers to sulk and ignore history in the making, because he's disappointed not to have met a live alien. His attitude is that of a child, not a scientist.
But it gets worse. Not only are Charlie's attitude and emotions poorly motivated, but he's not very intelligent for a scientist. There is no logical reason to believe that the alien race is dead.
1. The spaceship just arrived. They've been on the moon less than a day. The alien "tomb" was underground. Is it not logical to assume there might be other places on the moon where aliens are still alive? Perhaps underground? Imagine if an alien ship landed in the Sahara Desert, and immediately concluded the Earth was barren of all life. Not very bright, is it?
2. Even if the moon is barren, why assume the alien race is dead? Why assume this moon is their home world, the only place their civilization existed? On the contrary, Charlie already knows these aliens are a star-faring people. They came to Earth. Is it not logical to assume they'd be scattered among the stars? That this tiny moon was but a small outpost of their empire? That the reason they left maps on Earth directing us to this moon was, not because it was their most important world, but because it was their closest world to Earth?
And indeed, this is what the ship's captain (Idris Elba) concludes much later in the film. That this moon was but an outpost of the alien's civilization.
Well, duh! I figured that from the start. It sure took a while for these scientists to come around. Why were they so dense? It's not that I'm smarter. Real scientists would not have jumped to the conclusion of a "dead race" after less than a day on that moon. Well-written fictional scientists would likewise not have been so quick to make such blatantly false assumptions.
But writers Jon Spaihts and Damon Lindelof wanted to inject some drama into their story. And also extend the story to feature film length. So they dummied down their scientists, keeping the scientists stupid until they reached a turning point in the plot that required them to suddenly wise up.
Contrast this to a science fiction film such as 2001: A Space Odyssey. A similar setup. An alien race creates us (or at least guides our evolution), teaches us, and invites us to visit them. But their intent is apparently benevolent, albeit strange to our limited thinking.
For further examples of poorly motivated characters, see my analyses of In Search of Lovecraft, and Deadly Messages, and Dark Floors.