I would say horror stories are a subset of thrillers. So all horror movies are thrillers, but not all thrillers are horror. And there used to be a site that would let you make Venn Diagrams and I would have, but I can't find it. Damn it!

With that in mind, I don't think I'd call Jaws a horror movie. Right at this second, anyway. It's totally a scary movie, but not a horror movie. I'm trying to figure out where the entirely arbitrary line in my head is, and why. Hm.

[ten minutes pass]

Okay, the best I can come up with is: horror stories are about Evil. It can be mundane dude-with-a-chainsaw evil. It can be spooky walking-dead evil. It can be freaky alien-body-snatching evil. It can even be existential Japanese we're-all-fucked-for-no-reason evil. But there's gotta be some sense that what we're dealing with here is just Evil.

In Jaws, the shark is doing what sharks do. The movie's got fantastic scares. Quint's monologue about the Indianapolis is definitely a little horror story within the movie, but I feel like the movie overall is maybe too naturalistic to be a horror movie. (So: Duel, yes. Jaws, no.)

I will probably change my mind about this tomorrow, but I do like forming random theories. Feel free to poke holes, 'cause I'll have to come up with a more complicated theory and that's my idea of a good time. Speaking of existential horror...

In Jaws, the shark is doing what sharks do.

But can't you say the same about the body-snatching aliens?

But can't you say the same about the body-snatching aliens?

Yes, but they do it with evil intent. Sharks just want lunch.

Yes, but they do it with evil intent.

I would disagree in the case where the aliens are not intelligent.

Stupid is the purest form of evil.

I would disagree in the case where the aliens are not intelligent.

Not TV, but this put me in mind of the Horta on Star Trek.

Well, the Horta were intelligent; they were killing people for revenge or self-defense after the humans unwittingly killed Horta eggs.

Jaws is a monster movie, straight up. It's an implacable killer, it strikes from the darkness, unpredictably. You have to face the monster and kill it. It's exactly calibrated the same way as Halloween. Michael Myers is equally filled with motiveless malignance. Also, Quint at least ascribes evil to the sharks with "their dead white eyes" etc.

The 2 scariest movies I have ever seen are Failsafe and The Accused.

I saw Failsafe back before the neo-nuclear movies like Testement and The Day After came out. Chills, I'm telling you!

The Accused was scary because at the time I was Jodie Foster's character with more education, but just as stupid. It made me seriously rethink my drinking behaviour!

Stupid is the purest form of evil.

Are sharks stupid? More stupid than the alien? What's the difference? It's all one big biological imperative.