A book tour will be successful if it is well publicized and the author is an established writer. Julia is an establis...

Anthony December 18, 2013

^ that's for question 1061

Naz December 27, 2013

Let's diagram this together.

"A book tour will be successful if it is well publicized and the author is an established writer."

P: WP & EW ==> S
not S ==> not WP or not EW

"Julia is an established writer, and her book tour was successful."

P: EW & S

"So her book tour must have been well publicized."

C: WP

Being well publicized is one of the two sufficient conditions. Therefore, we cannot conclude that Julia's book tour was well publicized, because we only know that she is an established writer (one of two sufficient conditions needed for us to conclude her being successful) and that her book tour was successful (the necessary condition).

Answer choice (A) is not correct because it doesn't exhibit the same pattern of flawed reasoning.

"This recipe will turn out only if one follows it exactly and uses high-quality ingredients."

Remember, "only if" introduces a necessary condition, not a sufficient condition. So the correct way to write this out is:

RTO ==> FE & HQI
not HQI or not FE ==> not RTO

The recipe turning out is dependent upon it being followed exactly and using high quality ingredients, not the other way around.

Thus, answer choice (A) is diagrammed:

P: RTO ==> FE & HQI
not FE or not HQI ==> not RTO

P: FE & RTO

C: HQI

This argument is not actually flawed. Because we know that the recipe turned out. That means that we can conclude HQI.

Answer choice (C) is our answer because it follows the same pattern of flawed reasoning. We can diagram it out to be:

P: KS & W2x ==> D
not D ==> not KS or not W2x

P: KS & D

C: W2x

Answer choice (C) is taking the existence of one of the two sufficient conditions and the necessary condition to deduce the other sufficient condition, just as we encountered in the stimulus.

Hope this helps! Please let us know if you have any other questions.

Nina July 1, 2014

When you have "or" for Julia:
BTS - > Not WP or Not EW - do you need to have both sufficient conditions for the the BTS to be positive or just one? So is it either she is not well publicized or she is not an established writer ?

Could you just have one of suff conditions for it to be true? Ahhhhh!!

Nina July 1, 2014

One last thing:

I also chose answer A and understand why it is incorrect because of an error in diagramming "only if"

Moving forward, can we automatically rule out answer choices that do not contain the same sufficient/necessary key words? I.e Answer choice A wrote : "only it" and the stimulus did not have "only if", only "if"

Naz July 7, 2014

I think we should review Sufficient & Necessary conditions again. The sufficient condition is the condition that is dependent on another condition for its existence. Take for instance: this cake must have sugar in it to be sweet. So "being sweet" is dependent on whether or not the cake has sugar in it. Thus, "being sweet" is the sufficient condition. The necessary condition is the condition that is independent of the other conditions. It doesn't lead to anything else. In the example above "having sugar" is the necessary condition. Something can have sugar in it and not be sweet, e.g. spinach has natural sugars in it, but is not sweet. The sufficient condition is placed to the left of the Sufficient & Necessary arrow and the necessary condition is placed to the right of it.

Now let's look at the statement at issue in this question: "A book tour will be successful if it is well publicized and the author is an established writer."

Remember that "if" will introduce a sufficient condition. So our sufficient condition is: "it is well publicized and the author is an established writer." Our necessary condition is: "book tour will be successful."

Let's diagram:

WP & EW ==> BTS
not BTS ==> not WP or not EW

This doesn't mean that if Julia has a successful book tour that her book tour was well publicized and that she is an established writer. She could not have one or both of those variables and still have a successful book tour. We merely know that if she DOES have BOTH then she MUST have a successful book tour.

Answer choice (A) is not incorrect because of the presence of the "only if." It is incorrect because the argument is not flawed. If you refer back to the explanation I wrote above, you will see that we can conclude that she used "high-quality ingredients" because we know that the "recipe turned out." Our correct answer will not only be flawed, but it will have the same flawed pattern of reasoning.

It's not about the "words" that are used in the argument. We are looking for the pattern of reasoning, i.e. how the argument moves forward when it is diagrammed, which variables are used to deduce other variables, etc. So you cannot rule out answer choices that do not contain the same key words as the argument. It's about knowing what those key words mean and what they introduce.

Hope that helped! Please let us know if you have any other questions.