14.3: Causal Claims
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Magic doesn't cause food to appear on your table at dinnertime. Someone has to put some effort into getting it to the table. Effort causes the effect, we say. Similarly, houses don't just "poof” into existence along the edge of the street of a new subdivision, except perhaps in Harry Potter books. It takes a great deal of physical labor to create these effects. Although effort causes some events, other events are caused with no effort at all. For example, the moon's gravity is the cause of tides on Earth, yet the moon is not making an effort. It just happens naturally.
Cause-effect claims don't always contain the word cause. You are stating a cause-effect relationship if you say that heating ice cubes produces liquid water, that eating chocolate cures skin rashes, that the sun's gravity makes the Earth travel in an ellipse, or that the pollen in the air triggered that allergic reaction. The terms produces, cures, makes, and triggered are causal indicators; they indicate that the connection is more than a mere accidental correlation. Not all causal claims are true, of course. Which one of the previous ones isn't?
Here is a 1950s newspaper advertisement for cigarettes. The cause-effect claim is hidden between the lines. Identify it by rewriting it so it uses the word causes explicitly.
More Doctors Smoke Our Cigarette
Check for yourself—smoke our cigarette and see if you don't get less throat irritation.
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Smoking our cigarette causes less throat irritation than smoking other brands of cigarettes.
The causal claim about chocolate was false. If you want to cure a skin rash, try something other than chocolate.
We need to be careful and not to take causal claims too literally. Here is a causal claim:
6 I succumbed to nostalgia.
Literally, this is suggesting that there is something called “nostalgia” that caused me to succumb. But we know not to interpret it that way. Instead of making the abstract thing called “nostalgia” have these causal powers, it would be better to interpret the sentence this way:
My mental state caused me to choose actions that would best be described as reflecting an unusual desire to return to some past period of my life.
What is the best way to interpret this causal claim?
Extreme blondness brings bad luck; it cries out to be pillaged.
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ABefore concluding that blondness causes bad luck, namely being pillaged, it would be better to interpret the sentence [from the film White Material] along these lines:
In our community, people who are very blond often have unpleasant events happen to them that I would describe by saying, “That was unlucky.” Those unlucky events are caused by a belief, held by many people, that encourages them to pillage the homes, farms and businesses of very blond people.
Some scientific reports make causal claims, and some make only associational (correlational) claims. It’s important to be able to distinguish the two in order not to misinterpret what is being reported. Unfortunately, many claims are ambiguous and aren’t clearly one or the other. The next concept check will help you learn to distinguish these kinds of claims.
In one of the following three passages, the speaker is claiming not only that A and B are associated but also that they are causally related. In another, the scientist is more cautiously claiming only that there is an association between A and B. In the third, the scientist is being ambiguous, and you cannot tell which kind of claim is intended. Which passage is which?
i. Statistics reported by the Ugandan ministry of police establish a relationship between a person's age and whether he or she was a victim of violent crime in Uganda last year.
a. causal
b. only association
c. ambiguous
ii. Our study has now uncovered a link between inflation and people's faith in the stability of their economy.
a. causal
b. only association
c. ambiguous
iii. Eating too much licorice candy produces diarrhea.
a. causal
b. only association
c. ambiguous
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(i) b (ii) c (iii) a. The notorious word link is sometimes used to assert a causal connection and sometimes to assert only a correlation, so it is not a reliable causal indicator term. The claim about chocolate is false. The claim about pollen might or might not be true, depending on the circumstances. Because you don't know the circumstances, you are not in a position to call it false.
If you insert a cup of sugar into the gas tank of your gasoline-driven car this afternoon, its engine will become gummed up. This is a specific causal claim. More generally, if you put sugar into any engine's gas tank, the engine will get gummed up. This last causal claim is more general; it doesn't apply only to this sugar in your car, nor to this date. Because it mentions kinds of objects rather than specific ones, it is a general causal claim—a causal generalization. So causal claims come in two flavors, general and specific. Scientists seeking knowledge of the world prefer general claims to specific ones. You can imagine why.
An event can have more than one cause. If John intentionally shoots Eduardo, then one cause of Eduardo's bleeding is a bullet penetrating his body. Another cause is John's intention to kill him. Still another is John's action of pulling the trigger. All three are causes. We say they are contributing causes or contributing factors or partial causes.
Some contributing causes are more important to us than others, and very often we call the most important one the cause. What counts as the cause is affected by what we are interested in. If we want to cure Eduardo, we might say the bullet's penetrating the skin is the cause. If we are interested in justice, we might say that John's actions are the cause, and we would leave all the biology in the background.
Causal claims come in two other flavors in addition to specific and general: those that say causes always produce a certain effect, and those that say causes only tend to produce the effect. Heating ice cubes in a pan on your stove will always cause them to melt, but smoking cigarettes only tends to cause lung cancer. Scientists express this point by saying heating is a determinate cause of ice melting, but smoking is not a determinate cause of lung cancer. Rather, smoking is a probable cause of cancer. The heating is a determinate cause because under known proper conditions its effect will happen every time; it doesn't just make the event happen occasionally or make its occurrence more likely, as is the case with smoking causing lung cancer. If our knowledge is merely of causes that tend to make the effect happen, we usually don't know the deep story of what causes the effect. We understand the causal story more completely when we have found the determinate cause.1
The verb causes can be ambiguous. Speakers often say, “Sa moking causes cancer,” when they don’t mean determinate cause but only probable cause. We listeners must be alert so that we correctly interpret what is said.
Eating peanuts tends to cause cancer, too. But for purposes of good decision making about whether to stop eating peanuts, we would like to know how strong the tendency is. How probable is it that eating peanuts will be a problem for us? If there is one chance in a million, then we are apt to say that the pleasure of peanut eating outweighs the danger; we will risk it. For practical decision making we would also like to overcome the imprecision in the original claim. How much cancer? How many peanuts? How does the risk go up with the amount? If we would have to eat a thousand peanuts every day for ten years in order to be in significant danger, then pass the peanuts, please.
1 In some systems, there are no determinate causes to be found. So-called "stochastic systems" behave this way. Quantum mechanics is a theory of nature that treats natural systems as being stochastic in the sense that the state of the system at one time merely makes other states probable; it does not determine which state will occur. Systems described by quantum mechanics are stochastic systems. So are the systems of inheritance of genes, which the Austrian monk Gregor Mendel first described back in the nineteenth century.