Letter to the editor: According to last Thursday's editorial, someone

Question

Letter to the editor: According to last Thursday's editorial, someone who commits a burglary runs almost no risk of being caught. This is clearly false. Police reports show that at least 70 percent of people who commit crimes are caught. All burglars are criminals, so although some burglars will undoubtedly escape, a large percentage of them will eventually be caught.

Which one of the following arguments exhibits a flawed pattern of reasoning parallel to that exhibited in the argument that a large percentage of burglars will be caught?

(A) A large percentage of professional persons are self-employed. Thus, since nurses are professional persons, a large percentage of nurses are self-employed.

(B) Psychiatrists have medical training, and a large percentage of them also have social-work training. Therefore, some people who have social-work training also have medical training.

(C) Since a large percentage of professional persons have changed their careers, and since career changes require new training, all professional persons who have changed their careers required new training.

(D) A large percentage of doctors are specialists. Since anyone who is a specialist must have training beyond the usual medical curriculum, it follows that many doctors have training beyond the usual medical curriculum.

(E) Many engineers are employed in management positions, and since anyone in a management position needs training in management, many engineers need training in management.

rajdeep212003 · Answer

I think the ans is option a

The flaw in the original argument is:

“70% of criminals are caught” 
→ burglars are criminals 
→ therefore a large percentage of burglars will be caught.

That logic is flawed because it assumes that what is true for the larger group must also be true for a subgroup.

Option A follows the exact same pattern:

“A large percentage of professional persons are self-employed” 
→ nurses are professional persons 
→ therefore a large percentage of nurses are self-employed.

Again, it wrongly transfers a property of the larger group to one specific subgroup.

That is why A is the best parallel.

Quick elimination:

(B) Valid conclusion. If many psychiatrists have both trainings, then at least some people with social-work training also have medical training.

(C) Talks about all career changers needing training. Different structure entirely.

(D) This is actually reasonable logic:
many doctors are specialists + specialists need extra training
→ many doctors have extra training.

(E) Also structurally valid:
many engineers are managers + managers need management training
→ many engineers need management training.

So only A reproduces the same flawed reasoning pattern.

Answer: A

guddo · Answer

Letter to the editor: According to last Thursday's editorial, someone who commits a burglary runs almost no risk of being caught. This is clearly false. Police reports show that at least 70 percent of people who commit crimes are caught. All burglars are criminals, so although some burglars will undoubtedly escape, a large percentage of them will eventually be caught. 
 
Which one of the following arguments exhibits a flawed pattern of reasoning parallel to that exhibited in the argument that a large percentage of burglars will be caught?

The flaw is that the argument takes a statistic about a broad group, criminals, and applies it to a smaller subgroup, burglars.  A large percentage of all criminals being caught does not prove that a large percentage of burglars are caught . Burglars could have a much lower capture rate than criminals overall.

(A) A large percentage of professional persons are self-employed. Thus, since nurses are professional persons, a large percentage of nurses are self-employed.

Correct. This repeats the same flaw. It takes a statistic about a broad group, professional persons, and applies it to a subgroup, nurses. But nurses may not match the broader group’s pattern.

(B) Psychiatrists have medical training, and a large percentage of them also have social-work training. Therefore, some people who have social-work training also have medical training.

Wrong. This reasoning is valid. If some psychiatrists have social-work training and all psychiatrists have medical training, then some people with social-work training also have medical training.

(C) Since a large percentage of professional persons have changed their careers, and since career changes require new training, all professional persons who have changed their careers required new training.

Wrong. This does not transfer a broad-group percentage to a subgroup. It applies a condition to those who changed careers.

(D) A large percentage of doctors are specialists. Since anyone who is a specialist must have training beyond the usual medical curriculum, it follows that many doctors have training beyond the usual medical curriculum.

Wrong. This is valid: if many doctors are specialists and all specialists need extra training, then many doctors need extra training.

(E) Many engineers are employed in management positions, and since anyone in a management position needs training in management, many engineers need training in management.

Wrong. This is also valid. It correctly applies a rule to a group known to fall under that rule.

Answer: (A)

yc168 · Answer

OE for reference:

Overview:  
The letter writer wants to show that a claim made in last Thursday's editorial is false. In order to show this, the writer offers an argument for the conclusion that a large percentage of burglars will be caught. Two premises are presented in support of this conclusion: (1) at least 70 percent of people who commit crimes are caught; and (2) all burglars are criminals. But these two premises actually provide little, if any, support for the conclusion.

(1) indicates that criminals in general are caught at a high rate, and the argument concludes from this that burglars are also caught at a high rate. But nothing in the two premises indicates that the rate at which burglars are caught is at all similar to the rate for criminals in general. The premises don't even guarantee that any burglars at all are among the 70 percent of criminals who are caught. So the argument is flawed because it assumes that if a large percentage of the members of a group (criminals) have a certain property (getting caught), then a large percentage of any part of that group (burglars) will also have that property.

To answer this question you have to decide which of the arguments has the same type of flaw as the letter writer's argument.

The Correct Answer:

A  The conclusion of the argument in (A) is that a large percentage of nurses are self-employed. This conclusion is based on two claims: (1) that a large percentage of professional persons are self-employed and (2) that all nurses are professional persons. Thus it mistakenly assumes that if a large percentage of the members of a group (professional persons); has a certain property (being self-employed), then a large percentage of the members of any part of that group (nurses) will have that property. So (A) exhibits the same flawed pattern of reasoning that the letter writer's argument does.

The Incorrect Answer Choices:

B  The conclusion of the argument in (B) is that some people who have social-work training also have medical training. It bases this conclusion on two claims: (1) a large percentage of psychiatrists have social-work training; and (2) all psychiatrists have medical training. But in this case, if both (1) and (2) are true, then the conclusion must also be true, so the reasoning in (B) is not flawed at all.

C  The conclusion in (C), "all professional persons who have changed their careers required new training," is a claim about professional persons in the past. But there is no reason to think that the crucial premise in this argument, "career changes require new training," applies to the past. So the argument draws a conclusion about the past that is well supported only for the present. This is the only logical flaw in (C), and it is not the same type of flaw as the one in the letter writer's argument.

D  The argument in (D) also puts forward two claims: (1) that a large percentage of doctors are specialists; and (2) that all specialists have training beyond the usual medical curriculum. (D)'s conclusion, that many doctors have training beyond the usual medical curriculum, logically follows from these two claims. So the reasoning in (D) is not flawed at all.

E  The conclusion of the argument in (E) is that many engineers need training in management. This conclusion is based on two claims: (1) that many engineers are employed in management positions; and (2) that anyone in a management position needs training in management. But in this case, if both (1) and (2) are true, then the conclusion must also be true, so the reasoning in (E) is not flawed at all.

Letter to the editor: According to last Thursday's editorial, someone

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Letter to the editor: According to last Thursday's editorial, someone

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