Logical reasoning PrepTest 139 · Section 1 · Question 7

Incorrect. This answer reverses the logic in the stimulus, where the non-defective film and camera are part of the support to draw a conclusion about a refund being owed.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Problem - The photos developed at a store were bad
Potential causes ruled out - Film and camera weren't defective
Potential cause semi-ruled out - Customer claims to have handled film correctly
Principle - not Store processes pictures properly → Refund
Therefore - If claim is correct, the customer is owed a refund

Answer Anticipation:
Despite the stimulus being relatively short, there are quite a few details packed in here, so let's take our time in unpacking them. And when we want to unpack an argument, we should start at the conclusion—it defines the scope of the argument.

Looking at the conclusion, we should note two things. First, it's qualified—it's based on the customer's claim being correct. That claim was that they handled the film correctly, so for the purposes of this argument, we accept that it was handled correctly. Without that qualification, a flaw in this argument would be that it's relying on those claims being correct. Second, it can be justified by the principle provided—the argument wants to conclude that the customer is owed a refund, and it establishes a situation under which a refund is owed.

When an argument tries to apply a principle/conditional to a specific case, it will generally be flawed in that it doesn't fully establish the sufficient condition is present. Here, the relevant sufficient condition is that the store didn't process the pictures properly. Looking at the premises, we can see that the argument attempts to establish this by ruling out alternative causes for the unsatisfactory pictures. While it rules out defects in the camera and film, and mishandling by the customer (with the qualification in the conclusion), it never establishes that those are the only alternatives to the store not processing the pictures correctly. As such, this argument assumes that there aren't other potential causes of the unsatisfactory pictures, so any answer that rules out other explanations will be an assumption the argument relies on. It could also rule out all other causes and connect the details in the premises straight to the sufficient condition of the principle.

Answer Explanation:
This answer establishes that the sufficient condition of the principle is met and thus it applies, allowing the conclusion to be drawn. If, alternatively, there being a lack of defects in the film and camera and the customer handling the film correctly doesn't mean the store processed the film wrong, then the premises aren't enough to establish the sufficient condition of the principle. That would suggest something else might have caused the unsatisfactory pictures, and the argument would fall apart.

Key Takeaway:
When an argument relies on applying a principle to a specific case, by far the most common flaw is failing to establish that the principle applies, i.e., that the specific case meets the sufficient condition of the principle. When that happens, the correct answer will deal with that missing connection.

Also, when a conclusion is qualified and says that it's based on a statement being true, you assume that statement is true. There's no second-guessing it at that point, as multiple answers here tried to do!

Incorrect. These pictures weren't taken with a defective camera, so this answer doesn't apply to the situation in the stimulus.

Incorrect. The qualification on which the conclusion is based is that the customer's claims of not mishandling the film are correct, so for the purposes of this argument, we can't call those claims into question.

Incorrect. The conclusion is based on it being correct, so this answer is out of scope of the conclusion.