We walk out of the theater into the crisp night and laugh, “That movie was ridiculous” and proceed to point out plot flaws and the bizarre events that occurred. But there’s a distinction, I’ve realized, between realism and reasonableness.
We use the word realistic to mean both and it’s not quite accurate: suspension of disbelief is actually really easy and we don’t mind much at all that there’s aliens or zombies or people with super powers roaming about. That’s fine, it’s a movie made to be fictional and larger than life; we don’t dislike that. The parts that we really mean when we say ‘unrealistic’ is that the characters didn’t do the reasonable thing given their situation.
Transformers was decent (certainly better than it’s sequels) and while we’re entirely happy to suspend disbelief for giant alien robots than choose to take the forms of American earth cars we get really upset (if subconscious) in the part where the awesome giant robot gives the AllSpark cube to the relatively weak and flimsy human to run through the battlezone with. These sorts of plot decisions are made to sensationalize the movie but it actually resonates the opposite with us as viewers because it isn’t a reasonable action for characters in that situation.
So it’s not about how real the situation could be, it’s how reasonable the characters act within it.
We have a lot of classics in the action movie category like Terminator, Predator, Rambo and Robocop that are actually very reasonable movies because of the perhaps flat acting and very static characterizations. Are they ridiculous? Yeah, sure. But the characters (namely those played by Ahnold) behave in a predictable manner. He’s a robot sent back in time to protect understandably afraid and confused humans. This is a dynamic that feels right when played out. It isn’t realistic (time travel, robot singularity etc. etc.) but the interactions between the flat, unfeeling robot and the weak and dazed humans makes sense if we as the audience were put in the place of those actors. Compare this back to Transformers where if the robot gave us the AllSpark we’d look at him like he’s crazy: “Uh… why? You’ve got guns for arms and a 10 meter stride. You take it.”
The recent rash of Marvel movies are played out in the same way: Wolverine is actually a much better character than Magneto was in First Class – one knows what he wants and does it. It’s reasonable. It’s slightly unfair to compare static and dynamic characters like that, but the way Magneto acts when confronted with things doesn’t really make sense and we lose that connection to him since we silently deplore his actions. It’s like those horror movies where the girl is in the house and we know the killer is upstairs and instead of getting the heck away she decides to explore in the dark alone and weaponless and we sit there thinking “NO! What are you doing?! Don’t go up there. Go to the police! Get away!” This is done intentionally, of course, for that tension, but it shouldn’t be happening with the character’s we’re supposed to identify with.
Even insanity can be reasonable. We look at movies like Memento and characters like Dark Knight’s Joker or Inception’s Cobb (notice: all Nolan films) and we can actually develop a fairly deep bond with characters who although don’t represent us do the actions we would do if put in that situation. Now, are we insane? No. And it’s not really fair to put ourselves in Joker’s shoes since he is actually crazy, but his actions are reasonable given that characterization. In Memento he’s just trying to figure things out like any of us would. Inception is interesting because every character except for Cobb is static and serving him, so in a way each of them is a splinter of his personality (after all, it is his dream) and combines to create one unit who we can identify with. The actions of the insane might be unstable and unpredictable but still remain reasonable to us.
So, in the blue corner we have things like Mad Men or Memento – entirely earthly, normal, real environment with people acting reasonably within them. The yellow might be the Terminators and Predators or Shaun of the Dead type where there is some element of fiction to the world but the overall reactions to things makes sense to us. Green: any number of dramas and soaps or the serial killer movie (where the killer is just a normal – if deranged – human) where the characters do things that don’t make any sense given their environment and situation. I might even put Drive on the line between blue and green; it was realistic and worked but some of his actions made no sense to me. Red could be most things that are in theaters these days: The G.I Joes and Transformer 3s. The Fast and the Furious series started in the yellow and has moved down over time. These are the movies where even if we can suspend disbelief for the unrealistic aspects the people who inhabit the world don’t seem to follow any logic for their actions and so alienate us as an audience.
I’m entirely happy watching the yellow category – often those are the best – taking some fantastic fictional realm and providing a good adventure within them. It’s not that I’m a stickler for “Oh, well that would never work in real life” because those things are the cool part. Neo can fight an entire mob of Smith agents? Sure, he’s the one. His reasons for fighting them make enough sense that we don’t even mind the sheer ridiculousness of the fight scene itself. That’s the entertainment.
TL;DR It’s not about realism, it’s about having a character that does what makes sense instead what would raise the stakes purely for the sake of arbitrary sensationalism.