Academic Reading, Writing, and Speaking

Tracing causes and effects

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Demonstrating a connection between causes and effects is rarely simple. For example, to explain why a chemistry course has a high failure rate, you might use these steps:

List possible cause: inadequately prepared students, poor teaching, large class size, lack of qualified tutors, the desire of the department to weed out students, and so on.
Investigate each possible cause: To see whether inadequate preparation contributes to the high failure rate, you might compare the math and science backgrounds of successful and failing students. To see whether large class size is a contributing factor, you might run a pilot program of small classes and compare grades in the small classes with those in the larger ones. To see whether the department wishes to weed out students, you might interview the professors, the department chair, or the advisers.
After investigating the possible causes, weigh the relative impact of each cause and suggest appropriate remedies.

Post hoc fallacy

Because cause-and-effect reasoning is so complex, it is not surprising that writers frequently oversimplify it. In particular, writers sometimes assume that because one event follows another, the first is the cause of the second. This common fallacy is known as post hoc, from the Latin post hoc, ergo propter hoc, meaning “after this, therefore because of this.”

POST HOC FALLACY

Since Governor Cho took office, unemployment of minorities in the state has decreased by 7 percent. Governor Cho should be applauded for reducing unemployment among minorities.

Is the governor solely responsible for the decrease? Are there other reasons? It is not enough to show that the decrease in unemployment followed the governor’s taking office.