- Mon Jun 12, 2017 3:10 pm
#35943
Good question, Cindy! Conditional reasoning and causal reasoning are often confused, especially when the conditional relationship makes sense as a causal one. "If I eat food with a high salt content I retain water" is purely conditional in form, but it would be easy to draw a causal conclusion from it - that the salt content is causing the water retention. However, when the stimulus doesn't make that leap in the conclusion, or contains no conclusion at all (as is the case in many Must Be True questions), then we want to avoid making that leap ourselves and instead constrain ourselves to just using conditional tools to analyze the answer choices. In this case, if there was no conclusion, I would not pick an answer that talked about cause and effect, but would instead look for one that took advantage of the contrapositive, saying that whenever I do not retain water I did not eat very salty food.
If, on the other hand, the author uses a conditional premise to support a causal conclusion ("therefore, salty food causes me to retain water"), then you should absolutely attack that argument with causal tools and look for alternate causes, cause without effect, reversals, etc. Causal reasoning is more powerful than conditional reasoning, and so when both are present it's typically best to focus on the causality rather than the conditionality.
So, when faced with a conditional stimulus that has no causal claims in it, whether you are asked to weaken it, strengthen it, identify the underlying assumptions, deduce what must be true, point out a flaw in the reasoning, or anything else, you should usually consign any answer that brings up causation to the "loser" pile. The only time you would bring one of those causal answers back into consideration is if there are no better answers available that deal with conditional reasoning. As long as you have any answers that talk about sufficient and necessary conditions, you should focus on those as your contenders.
If that didn't help regarding the particular question you were looking at in the LR Bible, then tell me more about that question. I want to be sure we are looking at the same edition before I assume that we are looking at the same question, since I have at least two editions on hand and they do not have the same question on that page. Just give me a few key words from the stimulus and I'll be able to look at it with you.
Thanks for the question, and I hope this was helpful!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
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