I was wondering what the philosophical distinction between Ghost and Dark Pokémon was, and Zach said that Dark is evil, while Ghosts are dead. This sounded good at first, but as we thought about it it seemed overly simplistic. For one thing, it's not totally clear that Ghost Pokémon are straight-up dead Pokémon. Maybe the better word for Ghost Pokémon is "spooky"?

I propose to investigate this claim using Rigor. First, let's go through all the Dark Pokémon and evaluate their evilness:

UMBREON: Associated with literal dark by evolving from Eevee at night. Its Pokédex entries deal mostly with its body reacting to the moon and with its ability to spray poisonous sweat from its pores. Gross but not exactly evil.

POOCHYENA/MIGHTYENA: Pokédex casts both of these as plain old wild animals, aggressive and dangerous, but no more so than your Kangaskhans or your Scythers. Hyenas have been construed as "evil" in popular culture, but the Pokémon version a fearsome pack hunter rather than a mangy carrion feeder.

ABSOL: "It appears when it senses an impending natural disaster. As a result, it was mistaken as a doom bringer." A tragic Cassandra Pokémon! Certainly "dark" in a Phantom of the Opera kind of way, but not so much evil as misunderstood. The Baí Zé of Chinese mythology upon which Absol is based is a guardian spirit, and not even misunderstood as evil as far as I can tell. I've always kind of wondered why Absol is a Dark-type anyway.

DARKRAI: "To protect itself, it afflicts those around it with nightmares. However, it means no harm." Despite this reassurance from the Pokédex, Darkrai has been depicted as a villain in some non-main series games. He also really causes problems for people, in contrast to Absol, who's just cursed with foreknowledge.

PURRLOIN/LIEPARD: "Its cute act is a ruse. When victims let down their guard, they find their items taken. It attacks with sharp claws." Purrloin actually steals stuff! Liepard has "lie" in its name, although it doesn't actually lie as far as I can tell. Still! Theft! Definite evil in this evolutionary line!

ZORUA/ZOROARK: These are some tricky ninja foxes, capable of fooling you by taking on various other forms, and I suppose that it makes sense that trickster figures/agents of chaos would fall into the Pokémon definition of "evil" and therefore the Dark type. Like, what type would an Anansi Pokémon be? Bug, probably. But maybe also Dark.

MURKROW/HONCHKROW: "It is said that when chased, it lures its attacker onto dark mountain trails where the foe will get lost." "It is believed that seeing this Pokémon at night will bring about ominous occurrences." Definitely sinister, albeit in a fairly vague way. And on Honchcrow: "It is merciless by nature. It is said that it never forgives the mistakes of its Murkrow followers." And it's supposed to look like a mob boss. Definitely evil.

SNEASEL/WEAVILE: "Vicious in nature, it drives Pidgey from their nests and feasts on the Eggs that are left behind." I love how Eggs are a proper noun. And eating other Pokémon's innocent Eggs is definitely evil!

HOUNDOUR/HOUNDOOM: Hellhounds with curvy devil horns! The Pokédex's portrayal makes it sound like any other Fire-type that hunts in packs, but we can't pretend that a hellhound with curvy devil horns isn't supposed to be evil.

SABLEYE: It lives in caves, which are dark, so, literal darkness. It eats gems, which could be symbolic of greed, but the Pokédex entries don't bother to push that comparison. Supposedly Sableye is based on the "Hopkinsville Goblins", which are called "goblins" but were supposedly aliens. This one's a puzzler.

SCRAGGY/SCRAFTY: They have baggy pants, so they're like, the urban youth/hip-hop gang/breakdance-fighting Pokémon. And it's true that street gangs are bad, so I can see these guys qualifying as evil, although the interpretation depends on a dated stereotype. Sure, fine.

PAWNIARD/BISHARP: Bulbapedia claims that these guys look like old-timey Japanese bandits, but I don't know how you tell bandit samurai apart from honorable samurai. They do look sinister, but there's not enough here for me to say they're definitely evil.

VULLABY/MANDIBUZZ: Wearing skulls as diapers is pretty creepy! And Mandibuzz is actually referred to (albeit obliquely) as a sort of scavenger: "It grabs weakened prey in its talons and hauls it to its nest of bones." If we stick to the cartoon logic that makes hyenas evil because they eat dead stuff, then these vultures have to qualify.

DEINO/ZWEILOUS/HYDREIGON: Hydreigon is apparently based on Yamata no Orochi, a polycephalic dragon who was also evil(???) from Shinto mythology. The Pokédex says "This scary, three-headed Pokémon devours everything in its path!" Probably evil—but is a mindless force of destruction really "evil"? Hmm.

INKAY/MALAMAR: Malamar looks like Ursula, so there's that. It also "wields the most compelling hypnotic powers of any Pokémon, and it forces others to do whatever it wants", making the objectively creepy Hypno look tame by comparison. Evil!


TYRANITAR: It's Godzilla! But Godzilla isn't evil. Godzilla is a force of nature, whose powers of destruction affect mankind by turns for good and for ill according to its whim. Tyranitar is not evil! I'm not sure why it's Dark even!

NUZLEAF/SHIFTRY: Shiftry's species is "Wicked Pokémon", and Tengu are bad guys, if I remember correctly. The Pokédex doesn't do a good job of convincing me, but I can tell that they're at least intended to be evil.

CARVANHA/SHARPEDO: They have dreadful visages, that's for sure. And Sharpedo is "The Bully of the Sea"! Evil!

CACTURNE: "It becomes active at night, seeking prey that is exhausted from the day's desert heat." Preying on the exhausted is arguably evil, but if we found out that's how Fearow hunted, would we say Fearow is evil? I wouldn't. I think this guy's a Dark-type because it's nocturnal.

CRAWDAUNT: "Crawdaunt has an extremely violent nature that compels it to challenge other living things to battle." All its Pokédex entries make Crawdaunt sound like a Fighting-type! Not evil.

STUNKY/SKUNTANK: They're just skunks! They spray stinky fluid. They don't even spray it maliciously! These are Dark-types only for mechanical reasons, and definitely not evil.

SPIRITOMB: "Its constant mischief and misdeeds resulted in it being bound to an Odd Keystone by a mysterious spell." Evil.

DRAPION: "It attacks people and Pokémon that cross the desert. This has only furthered its bad reputation." Is that supposed to make it sound evil? Plenty of Pokémon attack those who trespass on their territory. Drapion has an angry expression, but I'm not seeing any evil.

SANDILE/KROKOROK/KROOKODILE: They wear sunglasses, and criminals wear sunglasses, and "crook"—Yeah definitely evil.

GRENINJA: It's Dark because it's a ninja, not because it's evil. Ninjas are kind of evil, but I don't think Greninja is evil. This is an edge case. I just noticed that Greninja uses its long tongue as a scarf. That is gross.

PANGORO: Okay this is great. Pancham, the baby panda Pokémon, "does its best to be taken seriously by its enemies, but its glare is not sufficiently intimidating." But if it levels up to 32 or higher while a Dark-type Pokémon is in the same party, it evolves into Pangoro, and NOW it is sufficiently intimidating. So here the Dark type very clearly represents a certain psychological toughness that the Fighting type on its own doesn't necessarily possess. Is Pangoro evil, though? "Although it possesses a violent temperament, it won’t put up with bullying." Explicitly non-evil!

If we take the "evil" of Zach's analysis above as the diabolical evil of Disney villains, we find very few Dark Pokémon that fit the mold. Even when we expand the definition to include thieves and gangsters, "Evil" still only accounts for about 60% of Dark Pokémon families.

After examining all these Pokémon so closely, though, I think I've come up with the quality that unites all (or almost all?) Dark-type Pokémon. The Dark type is for Pokémon who possess a certain sinister menace, one that often makes you think, at first blush, that they're evil.

I'm very happy with that analysis right now, but I hope you'll evaluate it for yourself, and perhaps we'll reach an even more precise understanding of Dark-type Pokémon. The original question, however, was the distinction between Dark and Ghost. Let's look at the Ghosts, and see whether they're dead:

MISDREAVUS/MISMAGIUS: Misdreavus lives in caves. It likes to scare people, and startle people. Mismagius "chants incantations. While they usually torment targets, some chants bring happiness." Neither is referred to as being the spirit of any dead entity. They're ghostlike in that they float, and are scary, but Mismagius seems more like "the witch Pokémon" than anything else. Misdreavus screeches like a banshee, but there's a lot of other stuff going on.

SHUPPET/BANETTE: Banette evolves from Shuppet, but the Pokédex says "This Pokémon developed from an abandoned doll that amassed a grudge." "Amassed" is completely the wrong word for that sentence, Pokédex authors! Anyway, Banette is more explicit about being a yokai than most yokai Pokémon, but it's a spontaneous spiritual manifestation, not the spirit of a dead entity.

DUSKULL/DUSCLOPS/DUSKNOIR: Duskull is a spooky grim reaper; Dusclops is a spooky empty mummy wrap; Dusknoir is a mummyesque psychopomp. We have a confirmed connection to death, but none of these guys are the spirits of dead entities.

YAMASK/COFAGRIGUS: The best Pokédex entry you'll ever read is Yamask's: "Each of them carries a mask that used to be its face when it was human. Sometimes they look at it and cry." CONFIRMED.

GASTLY/HAUNTER/GENGAR: Weirdly the Pokédex entries for Gastly and Haunter are mostly concerned with the fact that they're made out of gas. However: They did famously appear in the cemetery of Lavender Tower, and it's pretty clear, to me at least, that they were intended to be understood as the spirits of the dead Pokémon interred therein.

DRIFLOON/DRIFBLIM: The Diamond Pokédex entry says Drifloom are "formed by the spirits of people and Pokémon", which seems pretty conclusive, but it's odd that this concept isn't repeated anywhere else.

SPIRITOMB: "It was formed by uniting 108 spirits." Spiritomb very explicitly used to be something else, but now it is this spooky other thing, the spirit of MULTIPLE dead entities.

GIRATINA: Giratina lives in the Distortion World, but being a spooky weird dimension beyond our own doesn't make the Distortion World an afterlife.

LITWICK/LAMPENT/CHANDELURE: Lampent and Chandelure are terrifying anti-psychopomps who want to mess with your spirit at the moment of death and prevent you from passing on to the next world. Spooky! But they are not themselves the spirits of dead entities.

PHANTUMP/TREVENANT: "According to old tales, these Pokémon are stumps possessed by the spirits of children who died while lost in the forest." According to old tales?! Eh, good enough.

PUMPKABOO/GOURGEIST: "The pumpkin body is inhabited by a spirit trapped in this world. As the sun sets, it becomes restless and active." "It is said to carry wandering spirits to the place where they belong so they can move on." Yeah, okay.

SHEDINJA: Shedinja is a floating cicada husk, so it looks a lot like the spirit of a dead thing, but it appears when Nincada evolves into Ninjask—nobody involved is dying!

SABLEYE: It eats gems and lives in a cave! How is it a ghost of any kind?

FROSLASS: "Legends in snowy regions say that a woman who was lost on an icy mountain was reborn as Froslass." But it evolves from Snorunt, which is not a ghost.

ROTOM: Rotom possesses appliances and is mischievous. It's not something that died.

FRILLISH/JELLICENT: Scary jellyfish that drown sailors, but aren't dead.

GOLETT/GOLURK: Clay and stone animated by "ancient science"; not dead.

HONEDGE/DOUBLADE/AEGISLASH: "Apparently this Pokémon is born when a departed spirit inhabits a sword." Okay then! Dead!

In the Ghost type, the Western concept of ghosts as "the intangible part of a person stuck around after they died" butts up against Japanese stories of objects that spontaneously develop spirits of their own. The consistent through-line is the idea of a creepy Otherworld where spooky things come from and where the spirits of the dead are supposed to go.

Now, finally, we have a clear distinction between the two groups: The Dark type depicts monsters that are scary because they seem to mean us harm, and the Ghost type depicts monsters that are scary because they represent the unknown. 
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