Sunday, November 11, 2007

Local inference

Last week L and I were sitting at a cafe; as I finished my drink, I stood up to leave - and noticed that L was not done yet. I sat back, and as a matter of an apology, said "It is not because I am done, that everyone has to leave".
A little later, she came back to that sentence, pointing that it probably did not convey the meaning I intended. As often, I had liberally transposed a French structure into English, hoping for the best. It usually fails, most of the time because of idiomatic reasons, but in this situation I was fairly surprised: there is no such ambiguity taking place here, and in both languages, the logical relationship expressed by the sentence is identical.
The structure "It is not because [Condition], that [Consequence]" signifies that there is no causal link between the Condition and the Consequence. And yet, the meaning conveyed in each language is very different, because of what should be inferred. In English, it would be interpreted as "As this condition does not cause that consequence, it must be another condition that caused it", emphasizing the existence of another explanation for a phenomenon. This form exists also in French, but is not typical. Generally, it is meant as a challenge: "As this condition does not cause that consequence, a different reason will need to be produced in order for the consequence to be accepted as valid".
So when I tell you that "It is not because the point of this post is intricate, that you should give up reading it", when the Englishman in you may be looking for other reasons to give up (style, maybe?), your French side should remind you that really, one should not give up on something only because it is intricate.

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Monday, August 13, 2007

She's not that innocent

Yesterday, I came across that small piece on Clipmarks, which is challenging the myth that men are more promiscuous than women. From a mathematical standpoint, the argument goes, the average number of partners of men has to equal the average number of partners of women.

clipped from

The Myth, the Math, the Sex

EVERYONE knows men are promiscuous by nature. It’s part of the genetic strategy that evolved to help men spread their genes far and wide. The strategy is different for a woman, who has to go through so much just to have a baby and then nurture it. She is genetically programmed to want just one man who will stick with her and help raise their children.

But there is just one problem, mathematicians say. It is logically impossible for heterosexual men to have more partners on average than heterosexual women. Those survey results cannot be correct.

In fact, he added, the survey data themselves may be part of the problem. If asked, a man, believing that he should have a lot of partners, may feel compelled to exaggerate, and a woman, believing that she should have few partners, may minimize her past.

“In this way,” Dr. Gale said, “the false conclusions people draw from these surveys may have a sort of self-fulfilling prophecy.”

 blog it

I thought the argument interesting (and no, not only because of my gender), but there was something bugging me which stayed with me for the entire day; and after some thinking, I think there is a bit of a theoretical flaw in the argument.
To illustrate the flaw, consider a fictional planet, which is populated by one single man, and hundred women (feel free to reverse the proportion if the argument sounds sexist) and assume that, to resolve the obvious imbalance, the planet decided to adopt a harem-like social system. In that case, the lucky man would have a whooping average number of 100 partners, whereas the poor women wouldn't have much choice, and would total an average number of one measle partner.
Now granted, the flaw is a rather theoretical one. The US Census lists about 134 million men for 143 million women in the US in 2000, which is far from the situation described above; still, in that case, assuming an entirely heterosexual population, if every woman were to have exactly 1 partner, then men would have an average 1.06 partners - and the myth of the promiscuous man, while dented, would still hold...

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