QUESTION TEXT: Galanin is a protein found in the…
QUESTION TYPE: Strengthen
CONCLUSION: Galinin makes rats want to eat fatty foods.
REASONING: Rats that choose to eat fatty foods have more galinin.
ANALYSIS: This is a terrible argument. It’s possible, but there are other explanations:
- Eating fatty foods increases the level of galinin.
- Some other third factor increases the level of galinin and increases the desire to eat fatty foods.
We can strengthen the argument by eliminating one of those explanations.
- That doesn’t help. It just means that rats might sometimes eat lean foods even if they generally eat fatty food.
- It doesn’t matter if the brains contain fat. We’re talking about how much galinin (a protein) their brains contain and whether galinin makes rats eat fat.
- This is pretty vague. It’s quite possible, based on this, that fatty foods have 1000x the levels of galinin components than lean foods do.
- CORRECT. This shows that galinin (the cause) existed before the rats ate fatty food (the effect). It rules out the possibility that it eating fatty foods caused the increase in galinin.
- This could explain why those rats eat so much fat: they metabolize it less efficiently and so they need more. But it doesn’t tell us if galinin is an effect or a cause of eating so much fat.
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