- Fri Sep 23, 2011 4:02 pm
#1936
Complete Question Explanation
Flaw in the Reasoning, CE. The correct answer choice is (C)
Premise: Many symptoms of mental illnesses are affected by organic factors such as a deficiency in a compound in the brain.
Premise: The symptoms of mental illness vary among different countries.
Conclusion: The organic factors that affect symptoms of mental illnesses are not distributed evenly around the globe.
The relationship between the second premise and the conclusion is also causal, which can be diagrammed as:
The conclusion, which is easy to spot due to the conclusion indicator “this variation establishes that,” is based on the finding that the incidence of symptoms in people with mental illness varies among different countries. Because organic factors can affect the symptoms of mental illness, the author attributes the variation in symptoms to an uneven distribution (i.e. variation) of organic factors around the globe. Literally, the author believes that different symptoms in different places are the result of what organic factors are present, and the variation in those symptoms shows that the organic factors are not distributed evenly.
Arguments that draw causal conclusions are inherently flawed because there may be another explanation for the stated causal relationship. Take depression, for instance. If doctors treat depression differently in the U.S. than in Japan, then it is quite possible that depression would manifest itself differently in the U.S. than it would in Japan, because some treatments may be better able to control certain symptoms better than others. Cultural factors may also play a role in how the symptoms of depression are being reported. Because the author author assumes that there is only one cause for the variation in the incidence of symptoms in people with mental illness, you should attack the answers looking for a description of this error.
Remember—the key to determining the error of reasoning is to focus on the connection between the premises and the conclusion, not on whether the premises are factually true. In this instance, it would have been counterproductive to doubt whether organic factors can indeed affect the symptoms of mental illness, since the causal relationship between the two functions as a premise and should not be questioned. Instead, focus on how the premises were used to support the conclusion.
Answer choice (A): Although the author does not specify exactly how many different mental illnesses are being discussed, this is not a flaw. An author is not required to specify every single fact or statement within in an argument. The conclusion would be equally strong regardless of how many mental illnesses are being discussed.
Answer choice (B): This is an attractive answer at first glance because some students see the nutritional element as an alternative explanation for the variation in symptoms. Even if nutrition contributed to deficiencies in compounds in the brain and nutritional factors varied from culture to culture, this would most likely be an effect of the uneven distribution of organic factors (foods eaten vary from culture to culture, and are often largely based on what is available locally or regionally). As this answer describes another effect of the cause, this answer does not describe a flaw in the argument. Note that, even if you dispute that this is an effect of the cause, this answer would still not describe an error in the argument or show that organic factors are not responsible for the variation in symptoms.
Answer choice (C): This is the correct answer choice. If cultural factors significantly affect how mental illnesses manifest themselves in symptoms, this would provide an alternate cause for the observed variation among different countries in the incidence of symptoms in people with mental illness. The possibility that an alternate cause can explain the given effect challenges the implicit assumption that there is only one cause for that effect, thereby making the reasoning vulnerable to criticism.
Note that the idea in answer choice (C) could have been phrased in many different ways:
Answer choice (D): At first, this may seem like an attractive answer choice, since it describes a possible unwarranted assumption. However, the author never implied that any change in brain chemistry would manifest itself as a change in mental condition. If she made that assumption, its logical opposite would have to weaken the conclusion. It does not. Even if some changes in brain chemistry did not manifest themselves as changes in mental condition, this would be consistent with both the premise and the conclusion of the argument. After all, the premise stated that many symptoms of mental illnesses are affected by deficiencies in a compound in the brain, not general changes in brain chemistry.
Since the statement described in answer choice (D) is not necessary for the conclusion of the argument to be logically valid, it is not an assumption.
Answer choice (E): The author never discussed whether the causes of mental phenomena are only physical phenomena; the scope of the argument was limited to the causal relationship between organic factors and symptoms of mental illnesses. Furthermore, it would be relatively easy to check if the author made this assumption by examining whether its logical opposite weakens the conclusion. It does not. Even if mental phenomena were not simply manifestations of physical phenomena, this would be consistent with the conclusion that the variation of symptoms of mental illness is due to a variation in the organic factors that affect them.
Flaw in the Reasoning, CE. The correct answer choice is (C)
Premise: Many symptoms of mental illnesses are affected by organic factors such as a deficiency in a compound in the brain.
Premise: The symptoms of mental illness vary among different countries.
Conclusion: The organic factors that affect symptoms of mental illnesses are not distributed evenly around the globe.
The relationship between the second premise and the conclusion is also causal, which can be diagrammed as:
The conclusion, which is easy to spot due to the conclusion indicator “this variation establishes that,” is based on the finding that the incidence of symptoms in people with mental illness varies among different countries. Because organic factors can affect the symptoms of mental illness, the author attributes the variation in symptoms to an uneven distribution (i.e. variation) of organic factors around the globe. Literally, the author believes that different symptoms in different places are the result of what organic factors are present, and the variation in those symptoms shows that the organic factors are not distributed evenly.
Arguments that draw causal conclusions are inherently flawed because there may be another explanation for the stated causal relationship. Take depression, for instance. If doctors treat depression differently in the U.S. than in Japan, then it is quite possible that depression would manifest itself differently in the U.S. than it would in Japan, because some treatments may be better able to control certain symptoms better than others. Cultural factors may also play a role in how the symptoms of depression are being reported. Because the author author assumes that there is only one cause for the variation in the incidence of symptoms in people with mental illness, you should attack the answers looking for a description of this error.
Remember—the key to determining the error of reasoning is to focus on the connection between the premises and the conclusion, not on whether the premises are factually true. In this instance, it would have been counterproductive to doubt whether organic factors can indeed affect the symptoms of mental illness, since the causal relationship between the two functions as a premise and should not be questioned. Instead, focus on how the premises were used to support the conclusion.
Answer choice (A): Although the author does not specify exactly how many different mental illnesses are being discussed, this is not a flaw. An author is not required to specify every single fact or statement within in an argument. The conclusion would be equally strong regardless of how many mental illnesses are being discussed.
Answer choice (B): This is an attractive answer at first glance because some students see the nutritional element as an alternative explanation for the variation in symptoms. Even if nutrition contributed to deficiencies in compounds in the brain and nutritional factors varied from culture to culture, this would most likely be an effect of the uneven distribution of organic factors (foods eaten vary from culture to culture, and are often largely based on what is available locally or regionally). As this answer describes another effect of the cause, this answer does not describe a flaw in the argument. Note that, even if you dispute that this is an effect of the cause, this answer would still not describe an error in the argument or show that organic factors are not responsible for the variation in symptoms.
Answer choice (C): This is the correct answer choice. If cultural factors significantly affect how mental illnesses manifest themselves in symptoms, this would provide an alternate cause for the observed variation among different countries in the incidence of symptoms in people with mental illness. The possibility that an alternate cause can explain the given effect challenges the implicit assumption that there is only one cause for that effect, thereby making the reasoning vulnerable to criticism.
Note that the idea in answer choice (C) could have been phrased in many different ways:
- “takes for granted that cultural factors do not significantly affect how mental illnesses manifest themselves in symptoms”
“presumes, without justification, that no other factors can significantly affect the manifestation of mental illnesses”
“ignores the possibility that some other factor can affect the incidence of symptoms in people with mental illnesses”
“fails to exclude an alternative explanation for the observed effect”
Answer choice (D): At first, this may seem like an attractive answer choice, since it describes a possible unwarranted assumption. However, the author never implied that any change in brain chemistry would manifest itself as a change in mental condition. If she made that assumption, its logical opposite would have to weaken the conclusion. It does not. Even if some changes in brain chemistry did not manifest themselves as changes in mental condition, this would be consistent with both the premise and the conclusion of the argument. After all, the premise stated that many symptoms of mental illnesses are affected by deficiencies in a compound in the brain, not general changes in brain chemistry.
Since the statement described in answer choice (D) is not necessary for the conclusion of the argument to be logically valid, it is not an assumption.
Answer choice (E): The author never discussed whether the causes of mental phenomena are only physical phenomena; the scope of the argument was limited to the causal relationship between organic factors and symptoms of mental illnesses. Furthermore, it would be relatively easy to check if the author made this assumption by examining whether its logical opposite weakens the conclusion. It does not. Even if mental phenomena were not simply manifestations of physical phenomena, this would be consistent with the conclusion that the variation of symptoms of mental illness is due to a variation in the organic factors that affect them.
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