1-2 paragraphs only! 4-6 sentences each!
nstructions: Choose one of the short arguments below that no one else has chosen and, in a substantial post of 1-2 paragraphs, evaluate how well it follows the rules of causal arguments (Rules 18-21). Address the rules specifically in your response in order to earn credit (see example below).
Note: This is a group discussion, so there should be enough arguments below for each of you to choose a different one. Please do so!
Example argument:
Physical exercise improves people’s “executive function”—the set of psychological abilities involved in planning and executing a task. People who get regular exercise have better executive function than their age peers who don’t. This isn’t because people with better executive function exercise more. When inactive people begin exercising, their executive function improves.
Adapted from: Sandra Aamodt and Sam Wang, “Exercise on the Brain,” New York Times, Nov 8, 2007
Student response:
This is a decent causal argument. It clearly states that there is a correlation between exercise and executive function (Rule 18), although it doesn’t say anything to support that claim. It proposes that exercise is the cause and improved executive function is the effect. To deal with the alternative possibility (Rule 19) that better executive function leads to more exercising, the argument gives a reason to think that the proposed explanation of the correlation is the most likely (Rule 20): inactive people’s executive function improves when they begin exercising. Furthermore, since we know that exercise affects your body and mind in many different ways, it’s not totally implausible to think that it could improve executive function, although this argument does not propose any specific mechanism by which exercise does so. The argument leaves room for complexity (Rule 21) by making the modest claim that exercise “improves” executive function, rather than making the modest claim that exercise “improves” executive function, rather than making a less nuanced claim like, “Executive function is determined by exercise.” Thus, the argument is fairly good, despite the flaw that it offers no account of how exercise does what it’s claimed to do.
Instructor comments: This response addresses each of the rules in a systematic way, citing specific details from the argument to support its claims about how well the argument follows each rule. In thinking about how well an argument follows the rules of causal arguments, it’s important to do your own thinking about alternative explanations of correlations. In weaker arguments especially, the most important explanations might not be explicitly mentioned, leaving you to come up with them on your own.
Tips for success: A good argument about causes should do two things.
First, a good argument about causes should convince you that there really is a correlation between two things (Rule 18). Remember that a correlation is a systematic relationship between two things. Giving a few examples of one thing following another, for instance, does not prove that there is a correlation between the two things.
There are two main ways for an argument to establish the correlation. It might do this by citing sources that establish the correlation. Alternatively, it might give an argument by example or a statistical argument. When a claim about correlation relies on either of these techniques, you’ll need to apply the rules from Chapter IV (Sources) or Chapter II (Generalizations) to decide how well it does in establishing a correlation.
Second, a good argument about causes should convince you that the best explanation for that correlation is that one thing causes the other. To decide whether an argument does this, you’ll need to brainstorm alternative explanations of the correlation, as you did in Exercise 5.1 (Brainstorming explanations for correlations). Then, use the skills you developed in Exercise 5.2 (Identifying the most likely explanation) to figure out whether you think the best explanation of the correlation really is the one claimed in the argument. If you think there are better explanations for the correlation, then the argument has failed Rule 19, Rule 20, or both.
Rule 21 comes into play in two ways. First, some arguments will overstate the strength of their conclusions. If an argument seems to suggest that it has explained the entire cause of some effect, be suspicious that it is ignoring the complexity. On the other hand, just because an argument doesn’t address the full range of causes for an effect does not mean that the argument has failed to identify a genuine causal connection. For instance, when public health experts publish a study claiming that eating fast food causes obesity, the fast-food industry sometimes retorts, “Our products don’t cause obesity. Obesity is caused by a combination of genetics, diet, exercise, and other factors.” They’re right: diet isn’t the only cause of obesity. Still, this retort violates Rule 21 when (if) it moves from the claim that diet isn’t the only cause of obesity to the suggestion that eating fast foods does not contribute to obesity at all. Don’t make the same mistake when you are evaluating arguments.
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For your post, choose one of the following arguments (copy and paste it to the top of your post):
1. Watching television will kill you. A study of 11,000 Australian adults found that people who watch an average of six hours of television per day die about five years younger than those who watch no television. More generally, the study found that each hour of television that you watch as an adult chops about 22 minutes off your lifespan. This is partly because people tend to eat junk food while watching television, partly because time spent in front of the television is time away form healthy activities like exercising, and partly because people tend to be driven to watch a lot of television when they are lonely, isolated, or depressed, all of which can lead to worse health outcomes.
Adapted from: Steven Reinberg, “Too Much TV May Take Years Off Your Life,” HealthDay, Aug 15, 2011
2. Want your state’s football team to go to the Super Bowl? Legalize marijuana! In 2012, both Washington state and Colorado legalized marijuana. The Seattle Seahawks (from Washington) and the Denver Broncos (from Colorado) played in the Super Bowl the following football season. Thus, football teams from states that legalize marijuana go to the Super Bowl!
Adapted from: Anne Howeth, Twitter post, Jan 20, 2014, 7:38 pm
3. Eating a “Mediterranean diet” and getting regular exercise lowers your chances of developing or dying from heart disease or cancer. American doctors first encouraged the Mediterranean diet when they noticed how healthy the people were in countries that eat such a diet, including southern Italy, Greece, and Crete. Since then, several carefully designed studies have confirmed the correlation between eating a Mediterranean diet and lower incidence of heart disease and cancer. These studies reveal that the correlation is not the result of coincidence or of other aspects of life in Mediterranean countries.
Adapted from: Francesco Sofi, Francesca Cesari, Rosanna Abbate, Gian Franco Gensini, and Alessandro Casini, “Adherence to Mediterranean Diet and Health Status: Meta-analysis,” British Medical Journal 337 (2008) a1344
4. Serving in the military causes people to earn less money later in life. A decade after their military service, men who were drafted into the Vietnam War in the early 1970s earned about 85 percent as much as similar men who had not been drafted. Since people were chosen randomly for the draft, it can’t be that (future) income caused people to be drafted or that some other factor caused both being drafted and lower incomes.
Adapted from: Peter Dizikes, “The Natural Experiment,” MIT Technology Review, Jan 2, 2013
5. In researching best practices for Twitter users, Buddy Media found that tweets of between 71 and 100 characters get retweeted far more than either shorter or longer tweets. Therefore, keeping your tweets between 71 and 100 characters will boost the number of retweets you get.
Adapted from: Kevan Lee, “The Ideal Length of Everything online, Backed by Research,” Buffer, Mar 31, 2014
6. Depression causes brittle bones, according to a recent study by researchers at the Hebrew University of Jerusalem. The scientists drugged mice to induce behavior similar to that found in depressed humans. The “depressed” mice lost bone mass, especially in their hips and vertebrae. When given antidepressants, the mice recovered—both in terms of their behavior and their bone density.
Adapted from: “Connection Between Depression and Osteoporosis Shown by Hebrew University Researchers,” ScienceDaily, Oct 31, 2006
7. Some hocky sticks are made for left-handed players. Others are made for right-handed players. This wasn’t always the case. Left- and right-handed sticks were only introduced in the 1960s. Since that time, though, around two thirds of Canadians have used left-handed sticks and two thirds of Americans have used right-handed sticks. This is true even though most Canadians, like most Americans, are naturally right-handed. The only reasonable explanation is that being Canadian causes people to prefer left-handed hockey sticks.
Adapted from: Jeff Z. Klein, “It’s Not Political, but More Canadians are Lefties,” New York Times, Feb 15, 2010
8. Among British people born around 1970, there is a correlation between IQ as a child and vegetarianism as an adult. Those with higher childhood IQs were more likely to be vegetarians as an adult. Researchers considered the possibility that vegetarianism causes a higher IQ, but this would require the vegetarians to have become vegetarians when they were quite young. They found that this was not the case. The vast majority of vegetarians became vegetarians as teenagers or adults, not as children. It’s more likely that some other mechanisms are at work. For instance, higher IQ was correlated with greater educational attainment, which is correlated with vegetarianism. Perhaps having a higher IQ causes more education, which causes an increased likelihood of becoming a vegetarian. Even when researchers factored out education, however, they still saw a significant link between IQ and vegetarianism. More directly, then, maybe higher IQs increase the likelihood that one will respond to evidence about the health and other benefits of vegetarianism. There is presumably some mix of various mechanisms at work here.
Adapted from: Catharine R. Gale, Ian J. Deary, Ingrid Schoon, and G. David Batty, “IQ in Childhood and Vegetarianism in Adulthood: 1970 British Cohort Study,” British Medical Journal 334 (2006), 245
9. People read for fun much less often than they used to. The decline in recreational reading occurred at the same time as a decline in reading abilities in Americans, as measured by test scores and employers’ reports about employees’ reading skills. The correlation shows up on the individual level too. Individuals who read for fun more often score better on tests of reading abilities. Thus, reading for fun causes people to become better readers.
Adapted from: Motoko Rich, “Study Links Drop in Test Scores to a Decline in Time Spent Reading,” New York Times, Nov 19, 2007
Rule 18: Causal arguments start with correlations
The evidence for a claim about causes is usually a correlation—a regular association—between two events or kinds of events: between your grades in a class and where you sit in the classroom; between being married and being happy; between the unemployment rate and the crime rate, etc. The general form of the argument therefore is:
Event or condition E1 is regularly associated with event or condition E2.
Therefore, event or condition E1 causes event or condition E2.
That is, because E1 is regularly associated with E2 in this way, we conclude that E1 causes E2. For exampLe:
People who meditate tend to be calmer.
Therefore, meditation calms you down.
Rule 19: Correlations may have alternative explanations
Arguments from correlation to cause are often compelling. However, there is also a systematic difficulty with any such claim. The problem is simply that any correlation may be explained in multiple ways. It’s often not clear from the correlation itself how best to interpret the underlying causes.
First, some correlations may simply be coincidental. For example, though the Seattle Seahawks and the Denver Broncos both went to the Super Bowl in the same year that their states legalized marijuana—2012—it’s not likely that these events were actually connected.
Rule 20: Work toward the most likely explanation
Since a variety of explanations for a correlation are usually possible, the challenge for a good correlation-based argument is to find the most likely explanation.
First, fill in the connections. That is, spell out how each possible explanation could make sense.
Rule 21: Expect complexity
Plenty of happy people are not married, of course, and plenty of married people are unhappy. Still, it does not follow that marriage has no effect on happiness on average. It’s just that happiness and unhappiness (and, for that matter, being married or unmarried) have many other causes too. One correlation is not the whole story. The question in such cases is about the relative weight of different causes.
