The Barber Paradox

October 31, 2011

I recently listened to the Radiolab podcast on Loops that has a segment on The Barber’s Paradox:

The barber shaves only those men in town who do not shave themselves.

Who shaves the barber?

Apparently this paradox was a big issue for set theory. The following SQL works quite nicely to describe the statement “all people either shave themselves, are shaved by someone else, or don’t shave at all”:

shavedBy VARCHAR(40) REFERENCES Person(name)

INSERT INTO Person(name, shavedBy) VALUES(‘Floyd’, ‘Floyd’);
INSERT INTO Person(name, shavedBy) VALUES(‘Andy’, ‘Floyd’);
INSERT INTO Person(name, shavedBy) VALUES(‘Goober’, ‘Floyd’);
INSERT INTO Person(name, shavedBy) VALUES(‘Gomer’, ‘Gomer’);
INSERT INTO Person(name, shavedBy) VALUES(‘Opie’, NULL);

SELECT DISTINCT shavedBy AS barber FROM Person
AND shavedBy != name;

The result is:


The relational model defines Entities and Attributes on those Entities. So is the issue with the Barber’s Paradox that the language does not make a distinction between Entities and Attributes or is the self-referencing part problematic? Creating a Barber TABLE to go with the Person TABLE is the wrong approach but I think it is only wrong if a self-referencing Attribute exists. We could define a patient-doctor relationship with either a doctor Attribute or a Doctor Entity and both approaches would work fine.

The SQL solution to the Barber Paradox nicely handles additional cases like a new barber moves to Mayberry or Aunt Bee shaves some men in her spare time.


Nurturing Tiger Moms

February 2, 2011

Bryan Caplan discusses Tiger Mother Amy Chua and I’m completely on-board until he says the following:

But hasn’t all the musical practice indelibly shaped Chua’s children’s characters?  Highly unlikely.  Behavioral genetics finds roughly zero effect of parents on personality.

I think this is a misinterpretation of The Nurture Assumption. The theory states that a large part of a child’s personality is environmental, that is, “nurture” but that this influence is mostly from peers rather than parents or teachers. What I think Caplan forgets is that parents can have an impact on children by indirectly influencing who their peers will be.

For instance, parents can influence their children’s personalities indirectly by the neighbourhood they choose to live in. If I remember correctly, Judith Rich Harris claims that the age of the parent(s) and whether a child is raised by a single parent has zero impact on child personality once you correct for the neighbourhood influence.

In her WSJ article, Chua says the following:

Here are some things my daughters, Sophia and Louisa, were never allowed to do:

• attend a sleepover

• have a playdate

• be in a school play

• complain about not being in a school play

• watch TV or play computer games

• choose their own extracurricular activities

• get any grade less than an A

• not be the No. 1 student in every subject except gym and drama

• play any instrument other than the piano or violin

• not play the piano or violin.

How many of these rules do you think will significantly affect the relationship these children have with their peers? I’m guessing it is non-zero and possibly as important as neighbourhood/school choice.

Yes the title is a little “cutesy” and from the department of redundancy department but let me explain. This is a tale of two newspaper stories about graffiti. The first story is a follow-up to the Graffiti Photophrapher vs. Virgin Mobile article I previously mentioned. In the post I noted that I found it ironic that the image in question, that was supposed to represent transient street art, had the URL of an art gallery named Thisisnotashop painted above it.

I sent e-mail to Thisisnotashop with a link to the Toronto Star article. The reply I received caught me off guard. Read the rest of this entry »

Slice of the Kidney Pie

August 29, 2009

Will Wilkinson and Bryan Caplan are debating why people oppose organ markets. Caplan believes that all (or effectively all) people that understand the economics behind organ markets support it over, I’m assuming, the current heavily altruistic system. Wilkinson attempts to summarize the moral argument against organ markets as follows:

Human beings have a certain dignity that is central to the value of human life. That dignity ought to be respected, preserved, and protected. Allowing the sale of human body parts diminishes the dignity of those involved in the transaction and erodes respect for the dignity of human beings generally. Therefore, markets in body parts ought to be legally prohibited.

Read the rest of this entry »

Voting Signals and GTD

June 14, 2009

Robin Hanson over at the Overcoming Bias blog has a post about What Voting Signals. He links to a NY Times article that describes a change in Switzerland in which every “…eligible Swiss citizen began to automatically receive a ballot in the mail, which could then be completed and returned by mail.” The result of this natural experiment was that the voting rate unexpectedly declined.

Read the rest of this entry »

Sandals and Summer Tires

April 27, 2009

Today is the day. It is not the daffodils nor the bloodroot blooming, it is not the green grass nor budding trees. What truly signifies the arrival of spring is the day I wear sandals and my car wears summer tires. The winter tires were swapped for summer goodness and my sandals have come out of winter storage (i.e. the back of the closet). Oh happy day :-)

Developing Smokers Revisited

September 28, 2008

In a post about the prevalence of smokers in China I challenged the assumption that smoking is caused by misinformation promoted by Big Tobacco:

My skepticism has its roots in anecdotal evidence from a couple of scuba trips to Indonesia. A high number of the dive masters in Indonesia smoke. Misinformation does not seem to apply. These young men (all have been men) have a good grasp of health issues dealing with the risk of decompression sickness and poisonous stings (rarely lethal but painful) for themselves and the divers in their charge. They speak English and are exposed to westerners who preach the evils of smoking to them daily. Yet they smoke in droves.

A paper named So You Want To Quit Smoking: Have You Tried a Mobile Phone? provides another hint.

Using panel data from 2,100 households in 135 communities of the Philippines collected in 2003 and 2006, the analysis finds that mobile phone ownership leads to a 20 percent decline in monthly tobacco consumption. Among households in which at least one member smoked in 2003, purchasing a mobile phone leads to a 32.6 percent decrease in tobacco consumption per adult over the age of 15.

What I find most interesting about this paper is not the idea that cell phones can reduce smoking but that smoking and cell phones are somehow similar.

What I think is similar is that both cell phone use and smoking represent a type of public conspicuous consumption that takes place in a social setting. They are both social signals.

It is common to describe someone as the type of person who “wear their heart on their sleeve”. I’ve been thinking about this idiom since reading Nicholas Carr’s post about The OmniGoogle. Carr’s piece ends with a comparison between Microsoft and Google:

Google differs from Microsoft in at least one very important way. The ends that Microsoft has pursued are commercial ends. It’s been in it for the money. Google, by contrast, has a strong messianic bent. The Omnigoogle is not just out to make oodles of money; it’s on a crusade – to liberate information for the masses – and is convinced of its righteousness in pursuing its cause. Depending on your point of view as you look forward to the next ten years, you’ll find that either comforting or discomforting.

This post is neither about technology nor economics but about the concept of motivations. Google and Microsoft are similar in that they both hold an almost unassailable position of power in terms of their core product (desktop OS and search respectively) but that Google differs in that it cares about something deeper than money and this makes them somewhat scarier than Microsoft (in Carr’s view which I think I agree with).

How can this be? How can we trust purely monetary motivations more than moral ones? I think understanding this paradox is key to certain left-vs-right divisions. 

What it comes down to is whether or not you wear your motivations on your sleeve. I am not taking a left-misunderstands-the-right position here. The reverse can also be true. I believe one of the most important left-vs-right political divisions is a religious one (especially in the U.S.). It is not the belief in a higher being per se that is the root of the problem, it is potential motivations that are hidden from clear view. Small “L” liberals do not generally trust anyone that has religious motivations. The key to having faith and being accepted by people who do not share your faith is displaying a clear record of being able to demarcate the decisions you make in life from the religious doctrine you ascribe to. Catholic politicians must answer questions about contraception. Mitt Romney has to answer whether or not The Garden of Eden is in Missouri.

If you don’t know me, the question most likely going through your head right now is whether or not I am religious… it is important for you to understand my motivations when reading my opinions on the topic. And that is the point. Microsoft, with a history of self-interest based choices, can be more trustworthy than The OmniGoogle because Microsoft wears their motivations on their sleeve.

The “messianic bent” Carr describes is key. Al Gore has a messianic bent when it comes to Global Warming. We add the -ism and -ist suffixes to certain ideas to make this bent clear. Global Warm-ism and Global Warm-ist (who go to battle against Denial-ists). Hilary Clinton is a National-Healthcare-ist. Ralph Nader is a Corporations-Are-Evil-ist. Barack Obama is all of the above. Neocons are Bush-Doctrine-ists. America is imperial-ist. This new -ists are similar to the terms racist and socialist that have been proven over time to be negative forces. Like the word propaganda, the messianic -ism/-ist words are only used by people that are against the -ism or the messianic bent of the supporters of the -ism (the -ists). 

If you are an agent of change, you should check your sleeves often and ensure you are -ism proof.

David Brooks’ Op-Ed in the NY Times yesterday takes a swipe at the notion of individual liberty:

Near the start of his book, “The Conscience of a Conservative,” Barry Goldwater wrote: “Every man, for his individual good and for the good of his society, is responsible for his own development. The choices that govern his life are choices that he must make; they cannot be made by any other human being.” The political implications of this are clear, Goldwater continued: “Conservatism’s first concern will always be: Are we maximizing freedom?”

Goldwater’s vision was highly individualistic and celebrated a certain sort of person — the stout pioneer crossing the West, the risk-taking entrepreneur with a vision, the stalwart hero fighting the collectivist foe.

The problem is, this individualist description of human nature seems to be wrong. Over the past 30 years, there has been a tide of research in many fields, all underlining one old truth — that we are intensely social creatures, deeply interconnected with one another and the idea of the lone individual rationally and willfully steering his own life course is often an illusion.

Ummmm…. I’m a little confused. I don’t see how the notion that individuals should be free to make their own choices rather than have others force choices onto them is lessened by the knowledge that humans are extremely social animals. 

I don’t think I have to re-read (or re-watch) “A Clockwork Orange”. The question is not the degree to which Alex and his droogs are social, the question is whether we have a right to hold their eyes open with intrusive machinery against their will.

Flow of Expectations

July 22, 2008

Seth Godin writes a post explaining that marketers often forget to ask one critical question: Are they ready to listen? He goes on to describe a potential book selling opportunity in the early 90’s that did not pan out:

… I had published a book about a political issue. An activist’s handbook. I had 20,000 copies in my garage when I found out about a large march in Washington. I bought an outdoor booth and trucked the books down to DC. I stood on the Mall in my little booth and watched more than 250,000 people walk by in less than two hours. Every single one an activist. Every single one a demographically perfect match for my handbook. After 100,000 people had walked by and we’d sold only one book, I lowered the price from around $10 to $1 just to prove my point–that it wasn’t the book and it wasn’t the price, it was the ability of the audience to listen that mattered. This group, in this moment, was there to march, not to shop.

Most people, most of the time, steadfastly refuse to pay attention.

This is a great story that punctuates Seth’s claim that the question “are they ready to listen” is key. I’d like to generalize (and probably ruin the simplicity of his message) by claiming that the activist book selling failure at the march disrupted the marcher’s/customer’s “Flow of Expectations”.

A booth selling an activist book at a march disrupts the marcher’s Flow of Expectations at several levels. 1) carrying a book during a march is inconvenient and it is not how people see themselves marching, 2) most people have some kind of expectation of how they evaluate a book to purchase which does not involve serendipitously finding a booth during a march selling a previously unheard of book by an author they do not know, 3) reading a book requires a commitment of hours over potentially many days/weeks/months and people do not want to make that decision under tight time constraints, 4) there is a physical Flow in a march and people do not want to be left behind, 5) activists are often distrustful of profit motives and do not want to be seen as susceptible to marketing tricks, and 6) buying a book can be done at a time that does not take away from the meaning of what the marcher’s are doing.

There are probably many more disruptions in the marcher’s Flow of Expectations. Rather than asking “are they ready to listen?” we can ask “are we disrupting their flow of expectations” and take steps to minimize or eliminate the disruption.

The best case scenario is that you are enhancing the flow of expectations.

Garbage Bags and Spandrels

February 19, 2008

I love outdoor black garbage bags with the quick tie feature. Instead of a straight cut, the top of the garbage bag is cut in a curved shape so that you end up with two longer edges that are easy to grab.

Now I’m sure that quick tie was a wonderful feature on its own. Many garbage bag executives probably struggled with the idea of re-engineering their manufacturing processes to add this functionality. For me, I couldn’t care less about the extra handle-like feature. So why do I love them?

Well, having the curved cut has a positive side-effect. A spandrel in evolutionary biology terms.  The curved cut allows me to easily tell the “open” edge from the sealed edge. No more pulling back and forth between the two edges unsure of which side is supposed to open.

Now I’m sure there are other ways to distinguish edge that opens from the sealed edge but it makes me happy that this minor irritation was fixed inadvertently by a feature designed with a whole different purpose in mind.

RADBags with New Opening Detection Technology.  What a wonderful discovery :-)

This is mind boggling. I read the headlines that Young Chimps Top Adult Humans In Numerical Memory and I didn’t read past the first few sentences (something about people-think-they-are-so-smart blah blah blah blah). Then I saw the video and WOWZEE. The good stuff is about 55 seconds into the YouTube video embedded below. That is just an incredibly cool short-term visual memory trick. I wonder if it is unique to chimps or whether we lost that specific ability.

Sitting Winds

December 6, 2007

An RSS summary reads

Fall sitting winds down with Alberta legislators sitting around the clock.

And for the life of me I can’t parse that sentence. What on earth are “sitting winds”? Mind you, I have trouble with generic news headlines, especially Sports ones involving ducks and predators. The trick here is that “winds” is not “blowing winds” but “unwind with a book”. Here is the article if you care about the Alberta legislature. Sitting winds. Sheesh.

Oh, by the way. The headline was “Alberta’s Marathon Sitting Continues”. Crystal clear.