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Phil_Goetz5 comments on Excluding the Supernatural - Less Wrong

37 Post author: Eliezer_Yudkowsky 12 September 2008 12:12AM

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Comment author: Phil_Goetz5 12 September 2008 01:45:51AM 18 points [-]

Once, in a LARP, I played Isaac Asimov on a panel which was arguing whether vampires were real. It went something like this (modulo my memory): I asked the audience to define "vampire", and they said that vampires were creatures that lived by drinking blood.

I said that mosquitoes were vampires. So they said that vampires were humanoids who lived by drinking blood.

I said that Masai who drank the blood of their cattle were vampires. So they said that vampires were humanoids who lived by drinking blood, and were burned by sunlight.

I (may have) said that a Masai with xeroderma pigmentosum was a vampire. And so on.

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

(Strangely, some mythical creatures, such as vampires and unicorns, seem to be defined in a spiritual way; whereas others, such as mermaids and centaurs, do not. A horse genetically engineered to grow a horn would probably not be thought of as a "real" unicorn; a genenged mermaid probably would be admitted to be a "real" mermaid.)

Comment author: buybuydandavis 27 October 2011 08:18:16AM 4 points [-]

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Daniel Dennett has a cute one like this. Real Magic (the kind in Vegas) is not Real Magic (Abracadabra shazam poof!).

Comment author: dlthomas 19 December 2011 05:55:00PM 2 points [-]

I think my first encounter with this was James Randi, which makes a lot of sense. I don't know if it was originally his, either, though.

Comment author: buybuydandavis 25 August 2012 10:39:50PM 5 points [-]

Found the quote the other day. Makes sense that Randi knew it too. Apparently Siegel was a magician and professor too, who wrote a book on Indian magic.

youtube, Free Will as Moral Competence, Daniel Dennett at the University of Melbourne, Australia, 15:21 Dennett quotes from "Net of Magic", by Lee Siegel

Quote from book: "I'm writing a book on magic, " I explain, and I'm asked, "Real magic?" By real magic people mean miracles, thaumaturgical acts, and supernatural powers. "No, " I answer: "Conjuring tricks, not real magic."

Dennett: Real magic, in other words, refers to the magic that is not real, while the magic that is real, that can actually be done, is not real magic.

Comment author: [deleted] 26 August 2012 10:36:17PM 4 points [-]

Dennett: Real magic, in other words, refers to the magic that is not real, while the magic that is real, that can actually be done, is not real magic.

That's the same quirk in natural language by which a heavy drinker is not usually a drinker who weighs a lot. (<Adjective> <noun> can mean ‘a <noun> who/which is <adjective>’, or ‘someone/something who/which is <adjective>ly a <noun>’.)

Comment author: Alicorn 26 August 2012 10:39:45PM 1 point [-]

Thank you for articulating my problem with the "real magic" quote.

Comment author: shminux 26 August 2012 11:11:16PM *  -1 points [-]

Surely real magic is done through yet-unknown means. It might stop being magical some day, once explained (reduced), in compliance with Clarke's 3rd law.

Comment author: [deleted] 18 December 2011 11:15:08PM 3 points [-]

(Strangely, some mythical creatures, such as vampires and unicorns, seem to be defined in a spiritual way; whereas others, such as mermaids and centaurs, do not. A horse genetically engineered to grow a horn would probably not be thought of as a "real" unicorn; a genenged mermaid probably would be admitted to be a "real" mermaid.)

Dunno if it's because I'm not a native English speaker, but my intuition about the words unicorn and mermaid doesn't agree (whereas it does agree e.g. with Gettier about the precise meaning of knowledge, and most other similar problems about precise meanings of words).

Comment author: Prismattic 19 December 2011 01:39:36AM 3 points [-]

I am a native English speaker, and I don't agree with the quoted passage either.

Comment author: Vaniver 19 December 2011 03:15:14AM *  12 points [-]

I think this depends a lot on your exposure to centaur and unicorn myths. Both creatures were imagined in Greece; the centaur was just a mashup of man and horse, and the unicorn was just a kind of horned donkey found in faraway places. Thus, if you slapped a horn on some donkeys (or just found an oryx) you'd have a Greek unicorn.

But in medieval Europe, the unicorn became a symbol of purity, able to cure diseases and drawn to virgins. Oryxes can't cure diseases and aren't drawn to (human) virgins, which to a large extent is the point of a unicorn (to someone who adopts the medieval European imagination of unicorns).

Comment author: [deleted] 19 December 2011 11:44:25AM 1 point [-]

Yeah, that must be the reason. I'm not familiar with mediaeval myths about unicorns, so it means pretty much “a horse with a horn” (but I wouldn't count an oryx as one -- the uni- part means it has to only have one horn, doesn't it :-)), but on the other hand I know about the myth of the mermaids' singing (and Ulysses's strategy to cope with it) so I wouldn't count the top half of a woman glued onto the bottom half of a fish as one.

Comment author: Vaniver 19 December 2011 05:09:56PM *  3 points [-]

Interestingly, mermaid myths may have been deliberate hoaxes, which makes the question of a "real" mermaid even muddier.

I'm not sure how Ctesias or Aristotle would react to seeing an oryx- they might decide it's a new duoceros different from monoceri or they might say "oops, I guess we only saw depictions of monoceri in profile, they actually have two horns."

Comment author: ArisKatsaris 19 December 2011 05:16:41PM 8 points [-]

but on the other hand I know about the myth of the mermaids' singing (and Ulysses's strategy to cope with it

A nitpick: The Odyssey had sirens singing, not mermaids -- and those were half-bird women, not half-fish women. See how they were depicted in ancient times

Comment author: Alejandro1 19 December 2011 06:07:46PM 4 points [-]

In Spanish (and presumably also in whichever language is army's native tongue, if it is not Spanish) the word 'sirena' is used for both siren and mermaid, hence the confusion.

Comment author: [deleted] 21 January 2012 10:00:10AM 1 point [-]

Yes, it's Italian.

Comment author: DSimon 19 December 2011 03:32:22AM 2 points [-]

How about: Vampires are humanoids that can sustain themselves only by drinking blood? That excludes blood-drinking when done occasionally or as a cultural practice.

Comment author: MinibearRex 19 December 2011 04:11:14AM 0 points [-]

What about a human with altered biochemistry, such that they could synthesize all needed biological materials from compounds found in blood? Is that a vampire?

Comment author: dlthomas 19 December 2011 05:58:09PM 0 points [-]

"Only by", not "by only".

Comment author: MinibearRex 20 December 2011 07:36:13AM 0 points [-]

Fine. Humans that are incapable of metabolizing anything other than hemoglobin. Does that count?

Comment author: dlthomas 20 December 2011 03:41:27PM 2 points [-]

I'd call them a vampire, but it'd be partly in jest. DSimon's below would give me even less pause, and with a fuller list it seems to become entirely uncontroversial.

Comment author: TheOtherDave 19 December 2011 04:18:39AM 1 point [-]

If it turned out that there was a rare degenerative illness that prevented sufferers from absorbing nutrition from any source other than blood, would you agree that sufferers of that illness were vampires?

Comment author: DSimon 19 December 2011 04:46:11AM *  0 points [-]

Ack. Okay, I guess I have no choice but to add yet another qualifier. :-)

How about: Vampires are very long-lived humanoids that derive their longevity from drinking blood. I can't think of a mundane example that fits that description. Which I suppose was Phil's original point: the only useful definition of "vampire" is one which excludes everything that could plausibly exist.

Comment author: Peter_de_Blanc 19 December 2011 03:39:41AM 2 points [-]

My point was that vampires were by definition not real

So according to you, a mosquito that isn't real is a vampire?

Comment author: MinibearRex 19 December 2011 04:09:47AM 0 points [-]

His point is that: P(not real | vampire) ~= 1, which is not the same as: "vampire = not real". It's an if-then relationship, not a logical equivalency.

Comment author: Peter_de_Blanc 19 December 2011 04:45:06AM *  3 points [-]

I understand that Phil was not suggesting that all non-real things are vampires. That's why my example was a mosquito that isn't real, rather than, say, a Toyota that isn't real.

Comment author: MinibearRex 19 December 2011 05:23:27AM -1 points [-]

But there's nothing particularly special about a mosquito. It's still an incorrect application of modus tollens. We have: If something is a vampire, then it is not real. From this, we can infer (from modus tollens) that if something is real, then it is not a vampire. Thus, if a certain mosquito is real, it is not a vampire. However, there is nothing here that justifies the belief that if a certain mosquito is imaginary, then it is a vampire.

Comment author: Peter_de_Blanc 19 December 2011 09:29:40AM 2 points [-]

What's special about a mosquito is that it drinks blood.

Phil originally said this:

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Note Phil's use of the word "because" here. Phil is claiming that if vampires weren't unreal-by-definition, then the audience would not have changed their definition whenever provided with a real example of a vampire as defined. It follows that the original definition would have been acceptable had it been augmented with the "not-real" requirement, and so this is the claim I was responding to with the unreal mosquito example.

Comment author: MinibearRex 20 December 2011 07:08:37AM 0 points [-]

Ah. That makes more sense.

Comment author: wedrifid 19 December 2011 06:20:39AM *  31 points [-]

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Nonsense. If there was a creature that:

  • Used to be a normal living human
  • Still looks human
  • Has the same internal organs but none of them are functioning
  • Isn't vulnerable to hemlock
  • Has more strength than could plausibly attributed to humans according to our understanding of genetics
  • Has teeth which extend to fangs and then retract.
  • Can only be sustained by blood.
  • Definitely doesn't glitter. Ever.
  • Physically cannot enter people's houses due to physical restraint that seems to be only operating on the creature. Exception - can enter people's houses if invited.
  • Starts behaving like the human that they used to be except with extreme sociopathic and homicidal tendencies.
  • Is unaffected by getting stabbed in the chest by anything but a wooden stake. (Wooden stake kills him.)
  • Burns when exposed to sunlight, holy water or religious symbols.
  • Instantly turns to dust when staked, decapitated or sufficiently burnt via the aforementioned causes.

... then basically everyone would agree it was a vampire. LARPy Asimov is just being annoying when he tries to spin the question about the universe into a question about semantics.

Comment author: dlthomas 19 December 2011 06:02:12PM 0 points [-]
  • Definitely doesn't glitter. Ever.

... then basically everyone would agree it was a vampire.

Except some Twilight fans.

Comment author: JoshuaZ 19 December 2011 04:54:21PM 3 points [-]

The key issue seems to not be the fiction but that the elements creating your "vampire" are separate. Your Masai with xeroderma pigmentosum has vampiric properties because of distinct separate events. If there were say a single virus that made people both have a similar light aversion and made them desire blood, I don't think most people would have a problem calling them vampires.

Comment author: [deleted] 19 December 2011 05:35:34PM 1 point [-]

Indeed, I would not object to being called a vampire if I had porphyria. (I was going to write “call someone a vampire if they have”, but I realize they might conceivably find it offensive.)