Friday, January 9, 2009

Possible Girls

People have occasionally asked to see some of my professional work. So today I give you my wackiest published paper: Possible Girls. It explains how one famous theory about the truth of counterfactual statements implies that you can have a girlfriend (or boyfriend) who lives in another universe.

I should give some background. One of the big philosophical mysteries that philosophers try to figure out concerns counterfactual claims, also called modal claims. For example:
"If the Democrats had nominated Sharpton, they would've lost."
"If I hadn't worn any clothes to school, I wouldn't have graduated."

Most philosophers think that for a statement to be true, it has to accurately describe some part of reality. So the question is, what part of reality is being described by these statements? In reality, the Democrats didn't nominate Sharpton and I wore clothes to school. We want to say that the above counterfactual statements are true, but it seems that we can't do this unless there's some aspect of reality that they accurately describe. Lots of metaphysicians have theories about what this aspect of reality is. Some of these theories involve nonphysical entities ("abstract objects") that serve the function of making modal claims true. Other philosophers don't believe in nonphysical stuff, so they don't like those theories.

David Lewis had a crazy but interesting suggestion. According to Lewis, there are an infinite number of universes ("possible worlds") out there, one for each possible way the world could be. These universes are disconnected from each other in space and time, and set up so that nothing in one universe can cause events in another universe. Relations between these possible worlds are the stuff that our counterfactual claims were supposed to accurately describe. According to him, here's what makes "If the Democrats had nominated Sharpton, they still would've lost" true: Consider the closest possible world (that is, the universe most like ours) where the Democrats nominate Sharpton. Do they lose in that universe? If so, the counterfactual statement is true. If they win, it's false.

All the other universes, according to Lewis, are real in just the same way as ours is real. They're made of physical stuff just like our universe is, so you don't have to believe in any nonphysical stuff to believe in them. Since there's one of these worlds for each possibility, there are an enormous number of real people out there. Some of them are girls who are thinking of boys from other universes. Starting from there, I show how you can get a one-to-one relationship with someone from another universe. I deal with a bunch of problems -- for example, how can you make sure that your otherworldly beloved is interested in you and not the person just like you from the next universe? (It involves your beloved being immortal and using her immortality to sing out an exhaustive description of your universe.)

This paper was accepted by Pacific Philosophical Quarterly, which is actually a respectable journal. The referee said that it made him laugh out loud several times. It's only eleven pages and I think it's fairly accessible. Feel free to ask any questions you have in comments, and tell me if there are any problems downloading the paper.

20 comments:

corvus said...

I haven't read the paper yet, though I will, though it sounds like you managed to get a paper published in a philosophical journal that is basically about your dating life.

Well done sir. I applaud you, with four fingertips tapping lightly upon an open palm.

Also, I think the end of His Dark Materials might bear some relation to this conundrum.

rered: to get drunk all over town for the second night in a row

corvus said...

Ok, I read it. That paper is awesome. It is indeed laugh out loud funny. My favorite part was the bits about talking donkeys. And I actually learned something about philosophy! The ending was also very touching. I liked how you managed to be very thorough in your reasoning, yet a sense of playfulness was throughout. Also, there didn't seem to be any degree of self-absorbed term-humping that you see in so much academic writing; it was very clean and readable.

Also, Possible Girls would be an excellent band name. But what type of band could they possibly be?

Mixylevs: possibly the name of Neil's immortal girlfriend from the fifth dimension

Neil Sinhababu said...

Glad you liked it, Corvus!

Lewis was very popular in Australia, and I went to a conference down there this July. A famous philosopher had been telling everybody about the paper before I showed up, and I found that I had all these new friends! It was really cool.

Stephen said...

So your possible girfriend is that possible girl than which one more appealing to you cannot be conceived.

You're the St. Anselm of lonely bachelors everywhere.

matt w said...

I don't know that it would provide much consolation that she knows all along that you're going to break up with her. It seems tragic. Unless you stipulate that you want a girl who won't mind being dumped eventually.

And doesn't the argument show that there are arbitrarily many immortal girls who are in love with you but get none of your love? Modal realism is the cruelest theory ever.

suemind: totally the name of Neil's girlfriend from the fifth dimension, so take that

corvus said...

Nuh uh, matt w! Mixylevs is a clever allusion to silver-age Superman villain Mr. Mxyzytlk, god-like imp from the fifth dimension. Suemind might be Neil's girlfriend from the universe that comes first in the Alphabetical Stipulation though.

Neil! You can solves this! What is the name of your counterfactual girlfriend?

drip said...

At first, I had some major hangups about impossible girls. I have a wife, a mother, a mother-in-law, a step-mother-in-la, an ex-wife (and many actual ex-in-laws), 3 sisters-in-law, 5 sisters, a secretary, and a daughter. I don't need an impossible girl from another world. It's enough to just know that she's there and I'm here. If I need to rely on modal realism to keep her there, so be it.

And I laughed out loud.

matt w said...

Whatever her name is, she's definitely dishe.

TB said...

Re: Lewis

See, Phillip Pullman's "Dark Materials" series, which posits precisely such a Leibnizean spread of "possible universes," each differentiated by a single difference in contingent events/choices. The books are brilliant, too -- providing a challenge to the dominant Christian metaphysics of fantasy novels.

Whoops! Just noticed that Corvus already pointed this out!

BruceMcF said...

"Most philosophers think that for a statement to be true, it has to accurately describe some part of reality. So the question is, what part of reality is being described by these statements? In reality, the Democrats didn't nominate Sharpton and I wore clothes to school. We want to say that the above counterfactual statements are true, but it seems that we can't do this unless there's some aspect of reality that they accurately describe."

This seems like such an innocuous launch pad for going into alternate universes.

Why is not the potential truth value of the statement a statement about constraints imposed by social institutions? That is, we learn the constraints imposed on our behavior by rules of behavior both by experiencing success and experiencing failure in abiding by them, and so its natural to describe the constraints in terms of what we believe they would not permit to occur. Even where the hypothetical does not exist, the social institutions that the hypothetical are used to describe certainly do.

Neil Sinhababu said...

It's true, Bruce, that the statements I'm working with involve social institutions. But Lewis' theory covers examples like this as well: "If there wasn't any gravity, there wouldn't be any human beings."

That's a matter of physical laws, not social institutions.

Anonymous said...

There was already a band called Theoretical Girls.

corvus said...

Do theoretical girls have any good songs?

Do Christian metaphysics really dominate in fantasy? I mean, Tolkien are super Catholic, but LotR is clearly more influenced by the Germanic folklore than by Christianity. In fact, probably about 99% of fantasy is more influenced by the pagan religions extinguished by ( or appropriated by) Christianity than by Christianity itself. Hell, Narnia has fauns and minotaurs dwarves. His Dark Materials is probably on of the few fantasy novels that actually bases its metaphysical construct on some semblance of Christian myth, and leaves it absent of other influences.

BruceMcF said...

"But Lewis' theory covers examples like this as well: "If there wasn't any gravity, there wouldn't be any human beings."

That's a matter of physical laws, not social institutions.
"

But its also about constraint. That is, stated as a positive rather than a negative, it says that gravity was part of the evolutionary environment of every organism that our species descends from (back to the single celled organisms left behind as accidental contamination by the survey ships of the late lamented Orgga Empire, of course). But our language is designed to narrate actions, not to describe structural constraints.

OTOH, in the two option poll between the realists and the idealists, I vote "other".

Justin said...

I think that your utilitarianism may have an unnoticed role in this paper. She's immortal, and you're not. There are lots of concerns about such relationships (which can be found in any respectable work from the Sci-Fi/Fantasy genre). You can dodge them by noting that the two of you are not in causal contact, so those concerns won't apply--you won't have to watch each other grow old. But a non-utilitarian might think that these concerns are applicable even in situations where they don't directly cause distress.

Also, the lack of causal connection may be an issue, if there are causal constraints on knowledge. Of course, you can know some things about her (by stipulating that you are thinking of the being with such and such qualities). But you can't learn things about her by talking to her, observing her habits, or interacting with her--important parts of human relationships--you can only learn about her via deductive reasoning (making additional stipulations may change the girl you're in love with). Again, as a utilitarian, you probably won't care about that.

Actually, it just occurs to me that deducing more information about her could change the girl you're in love with, if facts about what you know about her are relevant to the closeness of her possible world to yours. That would be a dreadful result, if you were continually changing the object of your affection.

Neil Sinhababu said...

Interesting points, Justin. But remember that worlds are spatiotemporally isolated. So there's no time when she's alive and I'm dead, or when she's young and I'm old, just like I'm not any particular distance from her.

I think there may be clever ways to rig up the initial stipulation to deal with the issues you raise. If you want to learn more about her over time, perhaps you stipulate that for a portion of her life she looks like some actual person, and then some other actual person, and then some other actual person. That is, if you're into shapeshifters. But stipulations grounded in the actual world will probably useful to those who aren't as well.

There may also be some way to set up a stipulation in the beginning that sets up a way of binding any new information with the old info so you end up with just one person (who may be a very complicated person). But immortality gives you time to be complicated.

corvus said...

Since all that there needs to be for one of these girls to be out there is a possible counterfactual, doesn't that mean that we all have an infinite number or immortal girls singing our praises for all eternity in infinite parallel worlds?

Neil Sinhababu said...

That's right, corvus. The one section of the paper that got removed in the editing was on how we all have infinite possible fans and infinite possible haters out there. It makes me want to do more good things so my fans will be justified.

BTW, I'm more a Mixylevs guy than a Suemind guy, largely because Mixylevs sounds like she'd be a bit more frisky and quirky.

David Manley said...

neil, you shouldn't assume the referee was male, though in fact he was. ;)

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I liked how you managed to be very thorough in your reasoning, yet a sense of playfulness was throughout.


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