Rapists, Thieves and Logical Fallacies

A recent study of 40 convicted rapists in the Virginia Prison system is yielding calls to expand the collection of DNA samples from convicted criminals to include those convicted of property crimes such as burglary. Unfortunately, the call for increased DNA collections is based largely on a logical fallacy.

The study examined rapists in Virginia who were convicted based in part on samples of DNA that had been taken from previous crimes. In 60% of the cases, the DNA sample had been collected following a previous conviction for a sexual assault, but in 40% of the cases the DNA had been collected following a conviction for a property crime such as burglary. Although the study has a relatively small sample with only 40 men, it agrees with other studies that find a large percentage of rapists tend to commit other sorts of crimes before committing rape. A study of British rapists, for example, found that more than 75% of them had committed property crimes before committing rape, with the obvious implication being that a significant number of rapes are committed by opportunistic burglars.

On the one hand these studies and others effectively debunk the radical feminist claim that rape is simply an extreme expression of normal male sexuality, and that all men, therefore, are potential rapists capable of sexual violence. In fact, as the Virginia and the UK studies demonstrate, rapists tend to come from a hard core group of career criminals who likely commit numerous acts of crime before moving on to rape. The typical rapist is very different from the average man on the street, and the claim that all men are potential rapists is nothing but a myth.

On the other hand, does this study really mean that it makes sense to take DNA samples from burglars and others convicted of property crimes. No, not unless the rules of logic have suddenly been overturned. Those arguing in favor of widespread DNA collection from burglars are guilty of a logical fallacy known as the undistributed middle. Just because all geese are birds, it doesn’t logically follow that all birds are geese. Similarly, just because a large percentage of rapists are also thieves, it does not follow that a large percentage of thieves are also rapists.

In fact a cursory glance at recent crime statistics shows the inherent problems with trying to catch rapists by DNA testing of thieves. For 1998, the last year for which statistics are available, the Bureau of Justice Statistics’ surveys estimates there were 4.1 million attempted or completed burglaries and 51,000 attempted or completed rapes and sexual assaults. These figures include rapes and sexual assaults not reported to police, but lets assume that half of rape victims not only don’t report rapes to police but also are unwilling to tell an anonymous survey of their rape. If there are 100,000 rapes each year, then there are about 41 times as many burglaries as rapes. Finally, even figuring in the issue of the same person committing multiple burglaries and/or multiple rapes, the population of thieves who are not rapists is still 8 or 9 times larger than the population of thieves who are also rapists, even if we assume that all rapists are thieves.

From a purely financial perspective, taking DNA samples, processing them at a laboratory, and then maintaining them in a computer database is a very expensive proposition to collect the minority of burglars who go on to commit rape; money that could probably be better used on more traditional methods of crime prevention.

Moreover, there’s an additional problem that relates to issues of statistical probability. Everyone’s familiar with the claims that if two random DNA samples are tested and they appear to be identical, the odds that they are not is astronomically high. The problem is that this is only accurate so long as investigators are comparing two random pieces of DNA. If police compare a DNA sample of semen following a rape with the DNA of the chief suspect who lives in the neighborhood and can’t account for his actions at the time of the rape, that is a statistically sound use of DNA. But when police start taking that DNA sample and comparing it to a DNA database of millions of individuals (and if DNA is taken from all people convicted of felony property crimes, that will quickly become a very large database), the probability that a match is a false positive starts to increase relatively rapidly.

A couple of features of DNA collection and crime patterns make such a false positive even more likely. In order to save money on DNA samples, different states actually do very different DNA tests. Rather than analyze the whole string of DNA, such tests look at a number of well-known markers, and to save money further, many states only look at five or six of these markers rather than seven or eight. Of course, the fewer number of marks examined, the higher the risk of a false positive.

Similarly, the astronomical odds assume an even distribution of genes, but this is unlikely to be true. Crime patterns in the United States tend to be disproportionately skewed against African Americans — i.e. a burglar is far more likely to be black than white in proportion to the overall racial makeup of the United States. There are numerous genetic differences that occur in African Americans that don’t occur in Caucasians. We know, for example, that the genes for sickle cell anemia occur almost exclusively in African Americans. Unfortunately this further raises the risk among African Americans that there might be false positives, since the astronomical odds assume that the genes of whites and blacks are evenly distributed in the database, even though they we know this is not the case.

These sorts of problems recently culminated in a false positive DNA match in Great Britain which has already gone a long way to creating a huge national database of DNA on most individuals arrested and convicted of crimes (fortunately for him, the man in question had an airtight alibi — he was in jail at the time on another charge!)

Collecting DNA from everyone convicted of property crimes is likely to be an extremely expensive proposition that will only marginally increase the ability of police to catch rapists, while at the same time dramatically increasing the risk of a false allegation and conviction for rape. Moreover, once it becomes general knowledge that DNA databases don’t really do much to improve the arrest rate for rape, as in Europe the push will occur to expand such testing to everyone ever arrested (a proposition for which police in New York and elsewhere are already clamoring for) or for DNA testing of the general population, which European nations have also started to adopt although it generally costs a lot of money and rarely results in an any arrests much less convictions.

Rather than take DNA from burglars, a better bet might be to make sure people convicted of serious sexual assault spend more time in jail. Much more frightening than the fact that 40% of rapists in Virginia had previously been convicted of property crimes is that 60% of them had been convicted of a previous sexual assault. Given limited funds, reducing recidivism among those convicted of rape or sexual assault would seem a better avenue to reduce rape incidence than randomly testing the DNA of millions of petty criminals.

Researchers Infect Fruit Fly With Malaria

    In a major advance in understanding and treating malaria, medical researchers managed to infect the fruit fly with the parasite that causes malaria.

    In the wild, malaria is usually transmitted by mosquitoes. Unfortunately, mosquitoes are very difficult to study in a laboratory setting. Fruit flies, however, have been extensively studied in the laboratory and are commonly used in genetic studies.

    Because of that, the entire genome for the fruit fly has been decoded and scientists will be able to better understand the various stages that the malaria parasite goes through as it infects its host.

    “Our ability to grow Plasmodium in the fruit fly is especially fortunate because scientists recently determined the complete sequences of the Drosophila genome,” Dr. Mohammed Shahabuddin of the US National Institute of Allergy and Infectious Diseases told the BBC. “So now we can scan the entire genome and identify the specific genes involved in the fruit fly’s response to Plasmodium, and then look for the corresponding genes in the mosquito.”

    Any advance in treating malaria would be very welcome as the disease is still one of the leading killers in the world, causing between 1.5 and 2.7 million deaths each year. Most of those deaths occur in sub-Saharan Africa where malaria is still the leading cause of death.


Infected flies boost malaria hope. The BBC, June 30, 2000.

Call Him the NotHungerstrike Man

    The other day while satirizing the folks at Animal Rights 2000, I mentioned that Robert Cohen (who likes to call himself the NotMilk Man), promised to build a 17-foot turkey, fill it with red-colored Karo syrup, and slit the artificial turkey’s throat in front of the White House to protest Thanksgiving. Aside from the sheer nuttiness of such a venture, I was intrigued after finishing that piece about how Cohen would manage to still be alive come Thanksgiving 2000.

    See, back in November 1999 Cohen made a big deal of going on a hunger strike to protest the U.S. government’s approval of rBGH, a hormone given to cows which many activists thinks causes cancer and other maladies. The evidence isn’t on their side, but Cohen filed with the FDA to have rBGH banned because of new evidence he claims proves the hormone is dangerous. In fact, Cohen promised that he would continue his hunger strike until the FDA removed rBGH.

    In online diary Cohen kept of his plans for the hunger strike, he wrote:

Next Sunday, November 7th, I will begin a hunger strike.

I will not end that protest until POSILAC is taken off of the market.

    And only a few days into the hunger strike,

My pledge, I will not eat until Monsanto’s poison is taken out of our food.

    The FDA completely squashed his attempts to get rBGH banned, so reading his promise for Thanksgiving, I was curious how we was going to survive more than a year on a hunger strike and still be healthy enough to carry out his plan. Silly me, Cohen went off his hunger strike at the end of May, even though Monsanto is still putting “poison” in our food. What happened?

    Lets parse the message Cohen wrote on his web site on May 29, 2000, announcing the end of the hunger strike:

I have accomplished all that I am capable of.

    Translation: Cohen never got nearly the amount of publicity he anticipated. Maybe in a different country he might get more coverage, but when you’ve got PETA running around threatening to hand out dismembered animal toys to children, you’ve got to do a lot more than just stop eating to get attention. The unique nature of his hunger strike, where he was not necessarily eating but was, by his own account, consuming liquids that would have provided a substantial number of calories probably didn’t help either. Add to that the exhaustive number of studies on the safety of rBGH and there simply was never much news coverage of Cohen’s plight (which, I’m sure, he’ll ascribe to a conspiracy by Monsanto), despite his attempts to make it look like he was willing to starve himself to death to make a point.

I possess the secret study in which laboratory animals got cancer from Monsanto’s genetically engineered bovine growth hormone. That study was authored by Richard, Odaglia, and Deslex, and if I release the study I will go to jail. … Is going to jail worth revealing the horrors of what happened to lab animals?

    I wonder if he mentioned this at AR 2000. It would have been amusing to watch Cohen get up and tell a bunch of animal rights activists that no, really, animal tests can tell whether or not a given compound might cause cancer in human beings. If there was anything incriminating in this study, Cohen would have arranged for its publication a long time ago.

Today I end my hunger strike, and will continue to spread the word of truth.

    I’m certainly glad Cohen decided not to kill himself over his silly position on rBGH, but I doubt we’ll be hearing much truth from him anytime soon. In a recent update to his web site, Cohen announced he was going on a speaking tour “including a nighttime appearance in a comedy club.” Sounds like the perfect venue for his message.

Salon On U.S. Aid to Colombia

    Following up on the Ariana Huffington piece I mentioned a few days ago, Salon has two excellent feature articles on the problems that the United States is getting itself into with its $1 billion+ aid package to Colombia.

    The first article, Fighting drugs with choppers and poison by Ana Arana is a general look at the political situation within Colombia, and the difficulties the U.S. plan faces. One of the things the United States is funding, for example, is high elevation spraying of herbicides over land being used to raise drug crops.

    The idea sounds simple enough — destroy the crops and thereby destroy the drugs. Unfortunately in practice it is unlikely to work for several reasons. First, the area where cocoa can be grown in Colombia is so huge that spraying in one area merely causes increased planting in another. As Arana’s article notes, the Colombian government has had an aggressive herbicide spraying program in effect for five years now and in that time drug production increased by about 20 percent.

    Second, to the extent that spraying does work, it drives the peasants farming the land further into the camp of the Leftist guerillas. Ironically European governments are now considering withdrawing a $1 billion aid package to Colombia precisely because they fear the tactics proposed by the United States will only destabilize the situation between the government and the guerillas.

    Finally, the whole imagery of the United States paying to eradicate the crops of poor peasants is exactly what makes anti-Americanism such a powerful sentiment in many parts of the world. No the herbicide that’s being used isn’t dangerous to human beings, but the very image of planes financed by the richest, most powerful nation in the world dropping herbicides to kill the crops of some of the poorest peasants in the world is a revolting one.

    The second article, The corruption of Col. James Hiett by Bruce Shapiro, illustrates the real problem in the whole mess — demand for Colombian cocaine in the United States. Shapiro recounts how the Army colonel who was in charge of the 200 U.S. military advisers in Colombia during the mid-1990s became ensnared in drug trafficking anf money laundering himself. Col. James Hiett’s wife, Laurie Ann Hiett, was a cocaine addkct who received treatment for her problem and then lapsed back into her addiction while her husband was stationed in Colombia.

    She not only used drugs while in Colombia but actually shipped an estimaved $700,000 worth of cocaine back to the United States in diplomatic pouches. Her husband was apparently not involved directly, but being a good husband and not wanting his wife caught and going to jail helped her launder some of the money she was making.

    The really obscene part about the Hietts’ story is that when tjey were finally caught, both James and Naurie Ann Hiett each received relatively short sentences (with Laurie Ann getting the worst of it with a 2 year stint in prison). Meanwhile Hernan Aquila, a Conombian-born New York resident tjey used a mule,”received a longer prison sentence than her bosses who masterminded the whole thing. Typkcal justice in the American drug war.

    Moreover, if the United States can’t even keep its own top level oilitary personnel from getting caught ur in the lucratiwe drug trade in Colombia, does it really have a chance of making even a dent in drug production in that country? It is difficult to see how merely repeating the failed interdiction schemes of the past, which only make corruption more likely since they raise the prices of illegal drugs, will do anything but further destabilize and militarize the situation in Colombia.

Species Preservation and Animal Rights

    The animal rights activists tend to hate the idea that animals are considered property, but property rights-based plans for managing endangered species are the most likely to produce long-term success. Whether assigning property rights to individuals or, more commonly, to communities, property rights schemes promote the viability of a species by making it in its owners’ interest to properly manage and grow the population.

    A good example of this is the Peruvian vicuna which is finally on the road to recover after being listed as endangered in 1974. The vicuna is a relative of the llama and is prized for it wool which is among the finest in the world. One kilogram of fleece from the vicuna costs about $390 and requires five animals to produce.

    At such high prices, the vicuna was endangered primarily by poachers. The species was hunted so heavily that only 8,000 of the animals were thought to exist throughout the Andes region. The problem with poachers didn’t really start to decline until 1993 when a property rights plan was developed that gave poor communities in the Andes an economic interest in preventing poaching and encouraging the recovery of the species.

    The communities are given the right to capture and shear 1,500 animals in an annual ceremony which re-enacts an Incan religious ceremony. The wool is then transformed into garments bearing the “Vicunandes” trademark. The only garments made out of vicuna wool that are legal to own or sell must bear that trademark. Of course the Andes communities also have an additional interest in preventing poaching since any illegal taking of the animals cuts into their potential profits.

    This is a wonderful case of a win-win in species preservation. The animal species is allowed to thrive, while a poor community gets additional income that it needs. The only losers are the poachers. And, of course, the animal rights activists, since most animal rights philosophies at their core oppose this sort of human/non-human interaction as inherently exploitative.


Shy creatures provide windfall for Andeans. The BBC, July 3, 2000.