prep cr 112 为什么不能攻击结论的假设？ - ChaseDream

112. (32826-!-item-!-188;#058&006832) (GWD 8-Q38)

Unless tiger hunting decreases, tigers will soon be extinct in the wild. The countries in which the tigers' habitats are located are currently debating joint legislation that would ban tiger hunting. Thus, if these countries can successfully enforce this legislation, the survival of tigers in the wild will be ensured.

The reasoning in the argument is most vulnerable to criticism on the grounds that the argument

A. assumes without sufficient warrant that a ban on tiger hunting could be successfully enforced

B. considers the effects of hunting on tigers without also considering the effects of hunting on other endangered animal species

C. fails to take into account how often tiger hunters are unsuccessful in their attempts to kill tigers

D. neglects to consider the results of governmental attempts in the past to limit tiger hunting

E. takes the removal of an impediment to the tigers' survival as a guarantee of their survival

答案是e,我选了A。攻击结论的IF假设为什么不行？

再看下面这道题，答案是E，假设就是结论的IF假设，为什么又可以？

66. (35089-!-item-!-188;#058&007596)

Bank depositors in the United States are all financially protected against bank failure because the government insures all individuals' bank deposits. An economist argues that this insurance is partly responsible for the high rate of bank failures, since it removes from depositors any financial incentive to find out whether the bank that holds their money is secure against failure. If depositors were more selective, then banks would need to be secure in order to compete for depositors' money.

The economist's argument makes which of the following assumptions?

(A) Bank failures are caused when big borrowers default on loan repayments.

(B) A significant proportion of depositors maintain accounts at several different banks.

(D) The difference in the interest rates paid to depositors by different banks is not a significant factor in bank failures.

(E) Potential depositors are able to determine which banks are secure against failure.