QUESTION TYPE: Strengthen
CONCLUSION: You can lower your risk of getting Parkinson’s disease by eating less meat, seafood and other foods rich in iron.
REASONING: There is a correlation between a diet high in iron and Parkinson’s disease.
ANALYSIS: This argument shows a correlation. Whenever there’s a correlation, there are four possibilities:
- Iron causes Parkinson’s.
- Parkinson’s causes people to eat more iron.
- Some third factor causes both Parkinson’s and makes people crave iron.
- It’s a coincidence.
You can strengthen the argument by eliminating an alternative possibility. Note that the right answer is rather subtle.
- CORRECT. This eliminates an alternate cause. Specifically, number three in the list above. This answer eliminates the possibility that a genetic predisposition both causes Parkinson’s and also is associated with people eating more iron.
- So? The argument didn’t limit itself to meats. They said “foods high in iron”.
(Note: this answer isn’t saying “vegetarians don’t get Parkinson’s” or even “vegetarians are less likely to get Parkinson’s. The key factor is iron, not meat.)
- So? This is just a fact about iron needs. It doesn’t strengthen the idea that iron-rich foods will cause Parkinson’s.
- We are trying to strengthen the idea that reducing iron intake will reduce Parkinson’s risk. This answer doesn’t do that: if anything, it shows an additional factor that suggests in certain cases, reducing foods rich in poorly absorbed iron wouldn’t help much.
- So? The argument’s point was that lower is better. The argument wasn’t saying people will go lower, they were just saying what would happen if they did.
Want advanced LR strategies? → Try the LR Mastery Seminar
Graeme shows how 170+ scorers do LR in real time. Satisfaction guaranteed!