In this argument the author dtes a study correlating the amount of iron in a person's diet with
the person's risk of heart disease. The author also cites a well-established correlation between
diets that indude large amounts of red meat, which is high in iron, and the incidence of heart
disease. The author concludes that the correlation observed in the study is a function of the
correlation between read meat and heart disease. This argument suffers from a series of poor
assumptions, which render it wholly unpersuasive as it stands.
To begin with, the author provides no evidence that the study's results are statistically
reliable. In order to establish a strong correlation between dietary iron and heart disease, the
study's sample must be suffident in size and representative of the overall population of
heart-disease victims. Lacking evidence of a suffidenfly representative sample, the author
cannot justifiably rely on the study to draw any conclusion whatsoever.
Even assuming that the study is statistically reliable, a direct correlation between a high-iron
diet and heart disease does not necessarily prove that the former causes the latter. While a
high correlation is strong evidence of a causal relationship, in itself it is not suffident. The
author must also account for all other possible factors leading to heart disease, such as
genetic propensity, amount of exercise, and so forth. Lacking evidence that the heart-disease
sufferers whom the study observed were similar in all such respects, the author cannot
justifiably conclude that a high-iron diet is the primary cause, or even a contributing cause, of
heart disease.
Similarly, a correlation between a diet, which includes large amounts of red meat and heart
disease, does not necessarily infer a causal relationship. Lacking evidence to the contrary, it is
possible that red-meat eaters are comparatively likely to incur heart disease due to factors that
have nothing to do with the amount of red meat in their diet. Perhaps red-meat eaters are the
same people who generally overeat, and it is obesity rather the consumption of red meat
specifically that causes heart attacks. The author must consider and eliminate this and other
possible reasons why red-meat eaters are more likely than other people to suffer from heart
disease. Otherwise, I cannot accept the author's implidt daim that eating red meat is any more
likely to cause heart disease than eating other foods.
Even assuming that a high-iron diet, including a diet high in red meat, promotes heart
disease, the author cannot reasonably conclude that this causal relationship fully explains the
study's results. The author overlooks the possibility that other foods are also high in iron, and
that the study's participants ate these other foods as well as, or instead of, red meat. Without
accounting for this possibility the author cannot convincingly conclude from the study that red
meat is the chief cause of heart disease.
In conclusion, the argument unfairly assumes that correlation is tantamount to causation. To
strengthen the argument, the author must provide dear evidence that a high-iron diet
contributes to heart disease. The author must also provide dear evidence that people who eat
red meat are more likely to incur heart disease because of the amount of red meat in their diet,
rather than some other factor. To better evaluate the reliability of the study upon which the
author's conclusion depends, I would need more information about the size and makeup of the
study's sample. I would also need to know whether other foods are also high in iron and, if so,
which high-iron foods the study's participants ate on a regular basis.