#7 - If you know a lot about history, it will be easy for

[JKing]

Some of these I got right and I just need to make sure I am on the right path to getting them right. I hope this is not too much, if it is I can next time make these questions in different posts.

December Test 1998

LR Section 4

#7. I picked D, but why is it not B?

[Steve Stein]

This question is tricky because its based on flawed conditional reasoning. Did you diagram this one? If so, how, and if not, how did you approach it?

Let me know--thanks!

~Steve

[JKing]

No diagramm.

(A)- irrelevant. Whether they are or are not versed in history has nothing to do with what the argument above stated.

(C)- Has nothing to do with the argument. No where does it talk about people who are not intellectuals.

(E)- Same as (C)

(B)- I was unsure about. It says knowing history will make it easy to impress intellectuals, but that does not necessarily mean you will impress them.

(D)- This just sense to me, but no where does it talk about other things to impress them.

That is why (B) and(D) was pretty much a toss up. I picked (D) because in the end (B) did not mention how versed in history and therefore you dont quite know how versed they are with books. They may know history but not to the degree it takes to impress anyone. That may not be a great answer but thats the reason why I would like an explanation on (B) and (D)

[Nikki Siclunov]

The argument contains an error in conditional reasoning. We can diagram it as follows:

Premise 1: Know history Easy to impress

Premise 2: NOT read history books NOT know history

Conclusion: NOT read history books NOT easy to impress

The two premises can be combined by using the contrapositive of the second one. Thus:

Know history Easy to impress AND read history books

In other words, there are two necessary conditions for knowing history. Just because one of the two necessary conditions is not met does not mean the other necessary condition cannot be met. So, if you are not well versed in history due to a lack of history, we can only conclude that you don't know much about history (thanks to premise 2):

NOT read history books NOT know history

However, just because you don't know history doesn't mean you won't find it easy to impress intellectuals: this is a Mistaken Negation of the first premise. The argument overlooks the possibility that there are other easy ways to impress them (which is basically a prephrase that agrees with answer choice D).

Re: (B) - this is not something the argument overlooks. The author clearly pointed out that people who learn a lot about history find it easy to impress intellectuals. (B) describes a scenario that would only be possible if we make a distinction between "easy to impress" and "impress." Even so, this is not material to the argument, since both the premises and the conclusion discuss the ease with which we are able to impress intellectuals: the author makes no logical leap between "easy to impress" and "actually impress." Whether the intellectuals are actually impressed by your knowledge of history - well, the author does not care about that. And neither should you

[AJITSHARMA880]

The argument contains an error in conditional reasoning. We can diagram it as follows:

Premise 1: Know history Easy to impress

Premise 2: NOT read history books NOT know history

Conclusion: NOT read history books NOT easy to impress

The two premises can be combined by using the contrapositive of the second one. Thus:

Know history Easy to impress AND read history books

In other words, there are two necessary conditions for knowing history. Just because one of the two necessary conditions is not met does not mean the other necessary condition cannot be met. So, if you are not well versed in history due to a lack of history, we can only conclude that you don't know much about history (thanks to premise 2):

NOT read history books NOT know history

However, just because you don't know history doesn't mean you won't find it easy to impress intellectuals: this is a Mistaken Negation of the first premise. The argument overlooks the possibility that there are other easy ways to impress them (which is basically a prephrase that agrees with answer choice D).

Re: (B) - this is not something the argument overlooks. The author clearly pointed out that people who learn a lot about history find it easy to impress intellectuals. (B) describes a scenario that would only be possible if we make a distinction between "easy to impress" and "impress." Even so, this is not material to the argument, since both the premises and the conclusion discuss the ease with which we are able to impress intellectuals: the author makes no logical leap between "easy to impress" and "actually impress." Whether the intellectuals are actually impressed by your knowledge of history - well, the author does not care about that. And neither should you

Hello,

I do not understand this part:

The two premises can be combined by using the contrapositive of the second one. Thus:

Know history ---> Easy to impress AND read history books

Could you please explain in a much simpler manner?

I followed through to this point and then lost track because I don't understand how "easy to impress" substitutes for the overlooked possibility of other ways to impress.

Best,
Ajit.

[Adam Tyson]

Hi Ajit, I'll try to help!

A conditional statement, in its simplest form, is "if this, then that." For example, if I am invited to the party, I will go to the party. We can diagram this relationship as follows:

Invited to Party Go to Party

The contrapositive of a conditional statement is what you get when we say we don't have that second part (the "necessary condition"), and therefore we cannot have that first part (the "sufficient condition") Thus, if I now tell you that I will not be going to the party, you can infer that I was not invited. That can be diagrammed as:

Go to Party Invited to Party

The strikethroughs of those terms can be read as negations of the terms. This means "if I don't go to the party, then I was not invited to the party." We know the contrapositive must be true, because the original statement meant I was absolutely going to go to the party if I was invited. You'll hear and see the phrase "reverse and negate" in relation to diagramming the contrapositive, and you can see that the diagram does exactly that.

Now, let's say I also said "If I am invited to the party, I will buy a nice bottle of wine to bring to the host."

Now, my being invited to the party is sufficient to prove two different things: I will go to the party, and I will buy a nice bottle of wine to bring to the host. We can combine those statements into one, like this:

Invited to Party Go to Party AND Buy Wine

In the argument, we knew that if you don't read history books, then you don't know history. The contrapositive of that is if you do know history, you do read history books. Reverse and negate that claim to create this new way of looking at the relationship. And then, we can combine the two statements into one!

Know History Easy to Impress

Know History Read History Books

Combined into one:

Know History Easy to Impress AND Read History Books

Finally, here's a similar setup to the premises in the stimulus:

If you don't have a passport, you cannot board an international flight.

If you are allowed to board an international flight, you must have a boarding pass.

Combine the contrapositive of the first sentence with the second sentence, and we get:

If you are allowed to board an international flight, you have a boarding pass and a passport, or:

Allowed to Board Boarding Pass AND Passport

I hope that helps! If you are unfamiliar with conditional reasoning, start looking into it asap, as it is one of the most commonly tested forms of reasoning in the Logical Reasoning sections on the LSAT. It's covered in the LR Bible, in some of our free webinars, and of course, in our courses.