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)