Logical Fallacies: The Lecture/Demo

Brett Lang is writing about the dangers of dietary supplements, which, because they’re not considered drugs, aren’t regulated by the Food and Drug Administration and can be sold without being proven safe. To make his case that such products are hazardous, perhaps even deadly, Brett might make the following argument:

These supplements are virtually unregulated and therefore can be sold even if they have side effects as serious as high blood pressure, increased risk of heart attack, even risk of death, all of which could be prevented if the products were re-classified as drugs and regulated by the Food and Drug Administration.

Convincing as this might sound, Brett’s argument (if he made it this way) would make the serious mistake of mistaking one reason for the reason. The argument assumes that because a lack of regulation results in risks, the presence of regulation would eliminate risk. Of course, if lack of regulation were the only reason for the risks, FDA oversight might eliminate them, but we know that even FDA-approved drugs have sometimes serious side effects. Consequences usually result from many causes and eliminating just one cause rarely eliminates the consequence.

Aime Lonsdorf is writing about obesity and the fact that Americans, who used to gauge their fitness using just two measures—weight relative to height—have been obsessing about their Body Mass Indexes (BMI) since the term was coined by the US Surgeon General in 2001. She might be tempted to make the following argument:

The coining of the term Body Mass Index by the Surgeon General in 2001 gave Americans a new way to measure our fitness and ushered in an era of renewed interest in our percentage of body fat. BMI-consciousness motivated us to exercise more and maintain healthier diets so that we have reduced our national average BMI from 41.5 to 28.7.

Again, the argument may sound reasonable, but the fact that BMI has fallen in no way proves that we were more conscious of our BMI numbers. The two numbers share a relationship, but the argument mistakes correlation for causation the same way a person would be in error who concluded that “breakfast causes lunch.” Other numbers than BMI probably improved too despite our ignorance of them.

Tyson Still is writing about the effects of divorce on membership in youth gangs. In particular, he’s researching whether the lack of a positive male role model in the home is a good predictor of a teen joining a gang. He might very well make an argument such as:

The presence of a biological father in the home provides the structure that can keep a teen from seeking parental guidance outside the home, from gang leaders for example. In a typical gang, a startling 50% of the members have experienced a divorce in their lives.

While there is most likely a connection between “fatherlessness” and gang membership, the evidence offered here does not begin to demonstrate what it wants to. “Experiencing a divorce” does not justify the faulty conclusion of “living life without a father,” for starters. Not to mention the meaningless statistic about divorce. The percentage of Boy Scouts who have “experienced a divorce in their lives” might be close to 50% as well.

Tikeena Sturdivant is writing about Adrian Peterson’s remark that he is a “40 million dollar slave.” Though it’s tempting to dismiss Peterson’s analogy, Tikeena is looking for ways in which it is might be valid. In doing so, she might easily make this sort of argument:

On plantations, slaves were “recruited” and used for their physical abilities but denied education. In the NFL, the players, 70% of them black, are drafted by owners, 100% of them white, for their athletic skills alone. And if they get injured, they can be cut without pay.

While it’s hard to argue that football players are the pawns in a game played by wealthy owners, the analogy is so mixed here it’s hard to tell how much of it is relevant to the argument. What’s the NFL equivalent of denying slaves education? And what’s the slavery equivalent of being cut from the team?

Jon Otero is examining the relative dangers of obesity and a drug designed to combat obesity, Qnexa. He has a tricky argument to make, that Qnexa is the best option for obese patients to reduce their weight despite the health risks the drug itself has been shown to create. He might be tempted to avoid the argument altogether by making a claim such as this:

Since for many patients medication to reduce obesity is the only alternative to carrying dangerously high body weight, the important question is how to reduce the risks of Qnexa, and whether to prohibit its use to only those patients who can best tolerate it.

If he did so, Jon would be using the common logical fallacy known as begging the question, by using the conclusion he wants to reach as one of the premises of his argument. He should have to prove that Qnexa is the only option for patients; instead, he only asserts that it is.

Jesse Samaritano is arguing to determine whether file sharing is stealing or just a high-tech version of lending your paperback to a friend. In his essay, Jesse describes the argument made by supporters of peer-to-peer networks that facilitate illegal file sharing:

Peer-to-peer networks are useful for legitimate sharing of public domain or personal documents and therefore should not be shut down.

He hasn’t done so yet, but Jesse will likely refute this flimsy argument as an example of substituting the part for the whole. The benefits the networks provide are irrelevant to the fact that they facilitate criminal sharing, the same way the Mafia can’t justify its racketeering operations by pointing out that they give heavily to the orphans’ hospital. We also can’t defend cheating on our taxes by saying: “But I pay so much!”

Ally Hodgson is arguing that marijuana is incorrectly categorized as a Schedule 1 Drug. Marijuana’s “relative abuse potential” is not high, she claims, and neither does it have a high potential for dependence. It would be easy for Ally to make a sloppy argument on this point by saying, for example:

The truth is, every drug, every cleaning product, every household chemical, even common tools such as X-acto knives or razor blades can be abused, so the potential for abuse is no reason to consider any particular drug dangerous.

The claim is reasonable on its face, but it doesn’t address the actual situation. Marijuana wasn’t placed in Schedule 1 because it can be abused. The FDA considers “relative abuse potential,” not “the possibility of abuse.”

Dale Hamstra is writing about the impossibility of walking in a straight line while blindfolded. It’s a fun and fascinating topic that readers might well enjoy, provided he makes the right assumptions up front. It would be easy, though, for Dale himself to make a false first step and end up walking in circles:

It is quite obvious to anyone who gives it a moment’s thought that nobody can walk a straight line blindfolded. The only interesting question is why.

Such an opening would be a blend of faulty assumption and begging the question because it makes a claim for the reader the reader might not readily concede and takes the fun out of what would be entertaining to illustrate. Even if readers would predict a deviation from “straight,” it’s unlikely they would predict the wild spiraling meanderings actual test subjects do.

Cassie Hoffman is investigating the changing landscape of “privacy” in our increasingly digital world. Because the definition of privacy is a moving target, she will need to be very careful to use it consistently or risk making sloppy arguments:

When we post personal information about ourselves online, for example, regardless of how we configure our “privacy settings,” it would be naïve of us to expect Facebook—a company that makes money selling information about its users—to respect our confidentiality.

If her own definition of privacy is too fluid, Cassie might engage in accidental equivocation; in other words, substituting different meanings for privacy in different contexts. In the first meaning, we are entitled to reasonably expect Facebook will comply with its own privacy settings. On the other hand, if what Facebook sells is aggregate data (for example, that users who claim they are twenty-year-old men click a surprising number of ads for retirement housing), such as sale wouldn’t invade anybody’s privacy in a way that individual users could object to.

Eddie Jahn is arguing that certain overlooked statistics are better indicators of a baseball player’s value to a team than the commonly used RBI and batting average numbers that usually command high salaries. Because he’s relying on statistics to prove a statistical conclusion, he’ll need to be certain that the numbers prove what he says they prove:

It has been demonstrated in the majority of World Series games that the pitching staff that posts a better RE24 differential wins every time, whether that staff is favored or the underdog in any game.

Now, a statistic that correlates with winning World Series games a majority of the time might well be something to follow, but it might not help a manager hire a good staff for a simple reason. Another statistic is 100% accurate: the “comparative runs scored” number, or CRS, which says that if your staff gives up more runs than your team scores, you lose.

Tony Shilling is making a complex argument that Marvel Comics Inc. should not sue its own artists for making a few bucks selling commissioned drawings at trade shows of the characters they draw for Marvel. Is there any way around this restriction for the artists who could use the extra cash?:

The same talented artists could make money drawing caricatures of Barack Obama at trade shows and nobody would sue because Obama is not a licensed image or character. So perhaps these cartoonists should sell their work as “caricatures” of Captain Marvel or Deadpool.

The trouble with this false analogy is that there is no living person to caricature. Nobody can bring Obama to life by drawing him, but when the Marvel artist draws Captain Marvel for a kid at a trade show, he almost literally creates the real thing on the page, and that’s not caricature no matter how differently he tries to draw it.

Sam Sarlo has had enough of the War on Drugs and wants it to end. A common tactic of those arguing to end the government’s high profile eradication effort is that its true purpose is to provide politicians an easy campaign issue:

Washington doesn’t really expect to end drug use through law enforcement; no matter how much we spend arresting and prosecuting, we only succeed in putting more nonviolent people in jail, but being “tough on drugs” is a good way to get elected.

This argument is a blend of legitimate evidence and the motive fallacy, which attacks a program not because it’s ineffective but because it serves somebody else’s purpose. Plenty of programs, both useful and useless, get politicians elected. That’s no reason to eliminate the good ones, nor a reason to eliminate the bad ones.

Marty Bell is arguing in favor of illegal steroid use in baseball . . . well, sort of. He’s arguing that steroid use be legal in baseball, thereby eliminating the hazards of buying from illicit sources and self-injection, as well as the complaints that steroid use creates an unfair advantage for users. If everyone can use, personal choice will dictate. He might make this mistake if he’s not careful:

Fans love the long ball, so anything that helps sluggers hit more big home runs is good for the game, the league, the players who want to be popular and sign big contracts for breaking records!

This special use of the bandwagon fallacy puts popular opinion in charge of dangerous medical decisions they have no business judging. A similar argument could be made for more crashes at Nascar events, or for legalized dog fighting. (No, I’m not being fair either, but you see the point.)

Ashley Petit de Mange is arguing that recession is good for marriage, or at least bad for divorce lawyers. Apparently, during recession and high unemployment, the divorce rate declines, perhaps because divorce is so expensive. How she handles other explanations could cause Ashley some trouble if she’s not careful:

The numbers clearly show that when it’s easier to afford, divorce is more popular; and when money is tight, couples find it easier to stay together. The recent decline in the divorce rate cannot be explained by greater commitment between couples facing hard times; it’s just a matter of economics.

This false choice makes the unstated claim that only one explanation is possible. If nothing in the essay demonstrates that miserable couples are staying together and that love is no factor in marriages lasting, then merely showing that the cost of divorce is a factor doesn’t refute at all the possibility that couples pull together when times get tough.

Bill Brooks would like the US government to more clearly define the term “embryonic stem cells” so that the ban against their use in stem cell research can be reversed to the greater enrichment of medical science. Because his argument will cross back and forth over the line between science and morality, he will need to be very careful to avoid engaging in fallacies that mistake the arguer for the argument:

The same people who think it’s acceptable to compel a rape victim to carry to full term and give birth to the product of her attack want to deny Alzheimer and ALS patients a chance at a cure because of the “moral value” they place on a few strands of tissue that happen to result from the interaction between an ovum in a laboratory and a sperm cell.

Whatever the merits of this argument, it tries to poison the well from which is drawn the objection against stem cell research that it kills human life. Whether we like it or not, the same people can have both good and bad ideas, so associating an idea with people who are wrong about something else is no refutation at all.

Jon Gonzoph thinks science has failed to establish a causal link between violent video game-play and actual acts of violence by game-players. Because his essay depends on the quality and the results of controlled experiments with game-players, Jon’s challenge will be to avoid logic errors when drawing conclusions:

The three month study was not at all conclusive, since it failed to show any increase in aggression in the group that had played the game for at least two hours a day for more than three months, compared to control groups that played less-violent games or played violent games less frequently.

The obviously faulty reasoning here is to conclude that a careful experiment which showed no increased aggression was “not conclusive.” A more reasonable explanation is that playing the game every day for three months does not create a more aggressive person.

Tabitha Corrao is examining court-mandated rehab and counseling as an alternative sentence for “drug offenders.” Tabitha’s primary responsibility in her first essay is to avoid equivocation:

It is clear from the evidence that billions of dollars are wasted locking up drug offenders who would be better served by rehabilitation, and less costly to society. Literally millions of prisoners convicted of drug crimes could take advantage of such programs.

This argument very likely uses two definitions for “drug offenders” and “drug crimes.” Casual users convicted of simple possession might well benefit from rehab and return to society more productive. But dealers convicted of murdering other drug dealers are also in jail for “drug crimes.” Do we want to release them to rehab?

Brett Lang seems to be arguing that nutritional supplements can be quite dangerous and that better regulations would protect the public from unscrupulous companies selling useless, even hazardous products. Because supplements are not required to prove their efficacy or safety, Brett will have to guard against non sequiters:

The supplement needs to provide something nutritional that is missing from a person’s diet, be available in a common form such as a tablet, and be clearly labeled as a nutritional supplement. So how does it happen that useless, dangerous, even deadly products can be sold on the shelves of GNC after meeting these requirements?!

At least as they are reported to us in the argument above, nothing in the requirements obligates the maker to test a nutritional supplement for effectiveness or safety. So it does not follow (the Latin for that is non sequiter) that we have any right to expect efficacy or safety. Nor should we be surprised when the product has neither.

Joe Mleczko is arguing that it’s time to abolish Affirmative Action. There are countless ways to go wrong in this argument, but the type we haven’t shown yet as an example is the slippery slope, so I’ll try that one out here:

The Act was certainly a legitimate and well-intentioned program to reverse hiring and admissions injustices present in employment and higher education when it was enacted. Those injustices have been largely now successfully reversed. The danger of continuing the program is that in addition to “proportionally representing “ race, ethnicity, and gender in their hiring practices, employers will soon be required to hire a “quota-ful” of homosexuals, Muslims, atheists, geriatrics, and people with all kinds of developmental disabilities that make them unfit for any sort of work.

We can trust Joe not to make ugly arguments, I’m quite sure, but the slippery slope is insidious and can find its way into your own arguments very easily. Learn to recognize and avoid it.

Did I miss anyone? I’ll be happy to provide you specific advice about actual logical fallacies you may have committed. Just leave a Comment/Reply on any post you want reviewed.

About davidbdale

Inventor of and sole practitioner of 299-word Very Short Novels. www.davidbdale.wordpress.com
This entry was posted in David Hodges, In Class Exercise, Logical Fallacies, Professor Posts. Bookmark the permalink.

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