2. 错误类比

Example:

   The following appeared in a memorandum¹ from the owner of Carlo's Clothing to the staff.

    "Since Disc Depot², the music store on the next block, began a new radio advertising³ campaign last year, its business has grown dramatically, as evidenced by the large increase in foot traffic into the store. While the Disc Depot's owners have apparently⁴ become wealthy enough to retire, profits at Carlo's Clothing have remained stagnant⁵ for the past three years. In order to boost our sales and profits, we should therefore switch from newspaper advertising to frequent radio advertisements like those for Disc Depot."

A. First, the argument rests on a fallacy of post hoc, ergo proper hoc.

B. Another problem with this argument is that it suffers from a false analogy.

3. 证据遗失类逻辑错误

Example:

   The following appeared in the editorial section of a local paper.

   "Applications for advertising spots on KMTV, our local cable television channel, decreased last year. Meanwhile a neighboring town's local channel, KOOP, changed its focus to farming issues and reported an increase in advertising applications for the year. To increase applications for advertisement its spots, KMTV should focus its programming on farming issues as well."

A. The argument is based on a false analogy.

B. In addition, the arguer ignores other ways to increase the applications for advertising spots on KMTV.

七、逻辑问题例文分析

Case Study 4:

  The following appeared in the editorial section of a corporate⁶ newsletter:

  “The common notion that workers are generally apathetic⁷ about management issues is false, or at least outdated⁸: a recently published survey indicates that 79 percent of the nearly 1,200 workers who responded to survey questionnaires expressed a high level of interest in the topics of corporate restructuring and redesign of benefits programs.”

 Student Essay

   First, the argument does not address how the nearly 1200 workers were selected, so the representativeness of the sample is doubtful. If the workers were selected by voluntary participation⁹, then there is possibility that these voluntary workers tended to care more about management issues.

   Second, the argument does not prove the credibility of the answers of the workers.  It leaves open the possibility that workers who actually did not care about management issues may in a survey gave positive answers for various reasons.

   Third, the argument only confines to such management issues as corporate restructuring and redesign of benefits programs, which happen to have close and main influence on workers.

Revised Essay  

    Based upon a survey among workers that indicates a high level of interest in the topics of corporate restructuring and redesigning of benefits programs, the arguer concludes that workers are not apathetic about management issues.  Specifically, the arguer assumes that since 79 percent of the 1200 workers who responded to the survey expressed interest in these topics, the notion that workers are generally apathetic about management issues is incorrect. The reasoning in this argument is problematic in several respects.

    First, the survey itself is open to question. The argument does not indicate how the nearly 1200 workers were selected. If the workers were selected by voluntary participation instead of random¹⁰ sampling, then there is the possibility that these voluntary workers tended to care more about management issues. In this case, the representiveness of the sample is problematic. In addition, the statistics cited in the editorial may be misleading because the total number of workers employed by the corporation is not specified¹¹.  For example, if the corporation employs 2000 workers, the fact that 79 percent of the nearly 1200 respondents showed interest in these topics provides strong support for the conclusion. On the other hand, if the corporation employs 200,000 workers, the conclusion would be much weaker. Furthermore, the survey does not involve workers of other companies throughout the country.

    Another problem with the argument is that it makes a hasty generalization¹² about the types of issues that workers are interested in. It accords with common sense that workers would be interested in corporate restructuring and redesigning of benefits programs, since these issues affect workers very directly. However, it is unfair to assume that workers would be similarly interested in other management issues, ones that do not affect them or affect them less directly.

    In conclusion, this argument is not convincing as it stands. To strengthen it, the arguer would have to show that the respondents account for a significant and representative portion of all workers.  Additionally, the arguer must provide evidence to prove that workers do have general interest in other management topics--not just those that affect them directly.