The following memo appeared in the newsletter of the West Meria Public Health Council. “An innovative treatment has come to our attention that promises to significantly reduce absenteeism in our schools and workplaces. A study reports that in nearby East Meria, where fish consumption is very high, people visit the doctor only once or twice per year for the treatment of colds. This shows that eating a substantial amount of fish can clearly prevent colds. Furthermore, since colds are the reason most frequently given for absences from school and work, attendance levels will improve. Therefore, we recommend the daily use of a nutritional supplement derived from fish oil as a good way to prevent colds and lower absenteeism.”

In this argument, the author suggests usage of a nutritional supplement derived from fish oil to prevent colds and lower absenteeism. To support it, the author mentioned a study in East Meria where fish consumption is high and colds frequency is low, then attribute the most frequently reason for absences to colds. However, there are several logical flaws which undermine the reliability of this argument.

First of all, this study may be unreliable. The author didn’t give us how the study is conducted, and how many people participate in the study. For example, if only tens of people participate in this study, the result is unreliable because of possible bias. And if this study is conducted among only teenagers who are better immune to colds, the result is also unreliable. What’s more, because the study is conducted in East Meria, it may not reflect the situation in West Meria because of the different species of fish or other difference, so unreliable to people live in West Meria.
Even if the study is reliable, correlation is not causation, of course. If people live in East Meria used to eat fish and exercise, there will be a correlation between fish consumption and colds frequency, but this correlation can reflect nothing. The reason for lower colds frequency is more exercise, not more fish consumption.

Besides, lower colds don’t necessarily result in lower absenteeism. Although colds are the reason most frequently given for absences from school and work, it may be due to colds are the simplest reason. People may want to escape from school or work somewhen because of any reason, like tiredness or trip, but they cannot say out the actual reason but colds instead. So lower actual colds may not result in lower absenteeism.

At last, even if all the flaws mentioned above can be avoided, fish oil is different from fish. A daily use of nutritional supplement derived from fish oil may not have the same benefit as more fish consumption since absence of nutrition in fish oil such as specific protein and so on.

In conclusion, because of logical flaws mentioned above, the proposal may be not as proper as the author expected. In order to persuade me, the author should give more evidence to show the reliability of the study, prove the causation between more fish consumption and lower colds frequency, give more evidence to show that lower colds can result in lower absenteeism and show me fish oil has the same benefit as fish. Only with more clear evidence, this argument can be reliable.