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June 2007, Logical Reasoning 1, Question 2


Question two. Question two is a parallel flaw question because it uses the phrase, flawed reasoning, that most closely resembles the flawed reasoning used in the argument above. With the parallel flaw question our job is to find an answer choice whose structure matches the structure of the original argument.

It has to have the same kind of conclusion, the same kind of evidence. It has to use the evidence in the same way and they have to be bad in the same way, they have to have the same flaw. So before you can find a parallel argument you have to figure out what the argument is. So break the original argument down into its component parts.

We can find the conclusion after the helpful conclusory keyword therefore, therefore Rosa's dogs are moderate barkers. We then have three pieces of evidence. The first two are some all statements, all Labrador retrievers bark a great deal and all Saint Bernards bark infrequently. The third piece of evidence, each of Rosa's dogs is a cross between a lab and a Saint Bernard.

The flow here isn't particularly common, but hopefully you can see that this isn't a good argument. Just because her dogs are half Saint Bernard, half Labrador doesn't mean that their characteristics are exactly in the middle. A barky dog could have a barky puppy, even if it's not a purebred. In other words, a mixture doesn't have to have properties that are halfway in between the two things it's mixed from.

So, ultimately, that's what we're looking for in the answer choices so let's go see what they say. So answer choice A, it starts out good, all students who study diligently make good grades. But it doesn't have a second all statement. Instead of saying all students who do something else, in here it just says, well, there are some students who don't study diligently.

We need all and then another all. So A is not our answer. Go to B so it starts with two all statements, all type A chemicals are extremely toxic to humans, all type B are nontoxic to humans. This particular household cleaner is a mixture of type A and type B, therefore, it is moderately toxic.

Now, this is what we're looking for, it has parts that correspond to each of the parts in the original argument. Same type of evidence, same type of conclusion, uses the evidence in the same way, same flaw this is our answer. So just to see why the other answers aren't right, look at C. Now, C's problem can be easiest to identify by the conclusion.

We need Bob to be halfway between shorthand and calculus, not knowing both. Answer choice D also has a bad conclusion. So we need the Perry family to be halfway between Green County and Winn County, but instead part of them live one place, part of them live somewhere else. Same problem really with answer choice E, half the dresses in the closet are Kenisha's, half of them are Connie's.

We need the dresses to be halfway between Kenisha and Connie so I guess they both own them or something. Regardless, it's not parallel. So that means answer choice B is our answer.

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