A recent study shows that people living on the continent of North America suffer 9 times more chronic fatigue and 31 times more chronic depression than do people living on the continent of Asia. Interestingly, Asians, on average, eat 20 grams of soy per day, whereas North Americans eat virtually none. It turns out that soy contains phytochemicals called isoflavones, which have been found to possess disease-preventing properties. Thus, North Americans should consider eating soy on a regular basis as a way of preventing fatigue and depression.

　　In this argument, the arguer cites a study showing that North Americans suffer from an amazingly higher rate of chronic fatigue and chronic depression than people living in Asia. From an unknown source, the arguer states that Asians eat much more soy than North Americans, who eat almost none, and that soy contains disease-preventing properties. The arguer then concludes his or her argument by stating that North Americans should consider regularly eating soy as a means of battling fatigue and depression. This argument suffers from at least four critical fallacies.

　　For the sake of this argument, we will assume that the studies and the statistics about North Americans' and Asians' soy eating habits are correct, and that isoflavones have been found to have disease-fighting properties. Given that, there is still a problem with the arguer directly correlating the eating of soy with the prevention of disease and depression. First of all, simply because soy may have disease-preventing properties, that does not mean that it can therefore fight chronic fatigue and chronic depression. Fatigue and depression may not actually even be considered as "diseases", therefore even given the fact that soy has disease-fighting properties, it would have no effect on the "nondiseases" of fatigue and depression. Secondly, even assuming that fatigue and depression are diseases, they are not specifically mentioned as diseases that soy or isoflavones are able to prevent. Perhaps soy can help prevent osteoporosis (bone loss), mumps or even chicken pox, but that does not mean that it can specifically address the problems of chronic fatigue and chronic depression. These two critical weaknesses alone make the argument unconvincing.