LR Question 7 Explanation
QUESTION TEXT: The photographs that the store developed were quite…
QUESTION TYPE: Necessary Assumption
CONCLUSION: If the customer’s claim is correct, the store owes a refund.
REASONING: The customer says they handled the film properly. The film and camera worked.
ANALYSIS: Unusual. A necessary assumption question that uses linked conditional reasoning. Usually you shouldn’t diagram necessary assumption questions.
We have these facts:
- Customer says handled correctly (C)
- Camera not defective (
CD) - Film not defective (
FD) not processed correctly➞ refund (PC➞ R)
If the store didn’t process the film correctly, they owe the customer a refund. But the evidence doesn’t lead to improper processing. I’m going to draw the evidence on the left and the conclusion on the right:
C and CD and FD PC ➞ R
The author wrongly assumes they’re connected. To fix the argument, add an arrow connecting left and right. Here’s the missing premise:
C and CD and FD ➞ PC
If PC, then we can conclude ‘R’. Unusually, this answer is sufficient and necessary.
___________
- We’re must prove the store owed a refund. This says what happens if they owed one. Not helpful.
- CORRECT. This links the premises to the conclusion. This has to be true f0r the argument’s reasoning to work. Oddly, it’s also a sufficient assumption.
- The pictures weren’t taken with a defective camera, so this tells us nothing.
- The author talks about what happens if the client handled the film correctly. This is irrelevant.
- Same as D. This question is about what happens if the claim is correct.
Hey Graeme,
A bit confused about your explanation, specifically when you diagram it out – you say that you’ll put the conclusion on the right and then put ~PC -> R. But the conclusion is about the customer’s claim, not the film being processed. Is that an oversight? Does it not matter? Just trying to wrap my head around this one. Thanks!
Apologies for the late response, but it’s a good question so I still wanted to address it. You’re right that the conclusion is about the customer’s claim, not directly about the store’s processing. But Graeme is treating “the customer’s claim is correct” as shorthand for a bundle of facts: that the customer handled the film correctly (C), and that neither the film (FD) nor camera (CD) was defective.
So the conclusion becomes: If C and CD and FD, then R (refund). But the stimulus only tells us that IF the store processed the film improperly (PC), then a refund is owed (PC –> R). So the missing link is the assumption that:
If C and CD and FD, then PC
That’s why Graeme connects the left side (C and CD and FD) to PC -> R. It’s just making the structure of the reasoning explicit.
Hopefully that makes sense, it’s a bit tricky to spell out!