Which one of the following exhibits both of the logical flaws exhibited in the argument above?

(b) All chickens have beaks. This bird has a beak. So this bird must be a chicken.

(d) John is extremely happy , so he must be extremely tall because all tall people are happy.

答案是D,可我选的是B。为什么B不行呢？谢谢！！！

My understanding.

The question is talking about a character of someone/something.  B is not.  But D is.

 Say, it doesn't refer to whether I am one of people, but rather I am intelligent people.

Just be careful for such short tricky quesions.

All intelligent people are nearsighted. I am very nearsighted. So I must be a genius.

犯了A能推出 B,则有B则有A

典型的充分必要条件错误

少看LSAT, 会走火入魔的.

简单分析一下. 问题中有”both of the logical flaws”看到没有, 所以答案要符合这两个flaws.

Flaw1: 逆命题. A is B 推不出 B is A. 比如: human has 2 eyes不等于having 2 eyes is human.

Flaw2: 走极端. A is B 推不出Very A is Very B. 比如: All intelligent people are nearsighted推不出

Genius (Very intelligent)就是very nearsighted.

看答案. Ｂ中有１没有2. D中有1有2, flaws2为extremely happy is extremely tall.