一道比较奇怪的题目,大家一起讨论讨论

Choi: All other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates.

Hart: But consider this: Over 70 percent of all doctorate holders do not have a parent that also holds a doctorate

Which one of the following is the most accurate evaluation of Hart's reply?

A) It estalishes that Choi's claim is an exaggeration

B) If true, it eddectively demonstrates that Choi's claim cannot be accurate

C) It is consistent with Choi's claim

D) It provides alternative reasons for accepting Choi's claim

E) It mistakes what is necessary for an event with what is sufficient to determine that the event will occur

正确答案是C, 大家讨论下为什么

You are right about the conclusion, but not right on your analogy to explain.

Choi is saying if a child has doctorated parents it's more likely to have doctor's degree than the same child if it doesnt have such parents.(All other things being equal). Hart counters that there are more doctors without doctrated parents than those who have. Hart is confusing two different percentages.(why? ) This kind of percentage error  question appeared many times in LSAT, and most of them are flawed question, and some are weaken If I remember correctly.

For example, Woman over 40 tend to have much higher risk than woman under 40 to have premature baby, therefore a premature is more likely born to a woman over 40. 

It's consistent because they can co-exist. meaning the both statements are valid and not against one and the other.

Suppose there are 100,000 non-doctor parents and 10% of them (10,000) have doctor children.

Suppose again there are 10,000 doctor paretns and 15% (2000) have doctor children.

Then both Choi and Hart's statements are true.

This line of thinking can be dangerous.

Suppose there is a similar question

Instead of two people aguing. It's one person's argument goes like this

"Clearly, all other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates. This is because  over 70 percent of all doctorate holders have a parent that also holds a doctorate."

or vice versa

"Recent study  shows, all other factors being equal, children whose parents earned doctorates are more likely to earn a doctorate than children whose parents did not earn doctorates. Therefore, this study explains why over 70 percent of all doctorate holders in my university have a parent that also holds a doctorate."

Now what's the flaw of this logic? Or harder, it can ask you to evaluate whether it is valid logic and why.

Again the key here is not come up with a number, rather you have to see the statement about likely hood of a effect to a subject with  a variable on and off is irrelevant to the statement about the sheer percentage of that effect in a population.

Once one graps this. LSAT percent and number question will become easy.

There are questions like

80% of  percent airplane crash had one common thing assoicated with it, therefore that thing should be avoided to remdey potential crash.

More premature babies are born to women under 40, therefore to the contray of common belief, woman under 40 are more like to have premature baby than over 40.

on and on, same thing