Question #1063

Valid/Flawed?

Started by Gabriel · started 2020-12-28 00:29 · last activity 2021-01-05 13:36 · 1 reply

Hello, I am having trouble seeing how this argument is valid. As I was answering the question and trying to draw it out, it appeared to be flawed because the conclusion that having higher numbers of male ducks relative to female ducks (MMD) means that there are more older male ducks (OMD) seems to reverse and change the premise that in populations of more older ducks (OD), there tends to be a higher proportion of males (MMD). And converses are not valid, right? Let alone those that change the terms of the initial premise... Another question that I had on this is that I am not sure to what degree this element actually matters — because even though I thought the argument was flawed, I still had to accept it to be "valid" for the purposes of the Must Be True question and to infer based on its conclusion, right? In Must Be True cases, do I need to be checking the validity of the argument so carefully? It didn't impact me getting the answer right or wrong because I had to accept the passage anyway and infer from it... plus it took up a lot of time. Thanks so much!

Replies

  1. shunhe · 2021-01-05 13:36

    Hi @Gabriel, Thanks for the question! This is a valid argument. So we’re told that there are it’s a 55:45 male/female ratio in the western lake, and 65:35 in the other lake. And the ratio is higher for older ducks. So, the argument concludes, we can say that since there are more adult male ducks anyway, the greater the disparity in the sex ratios, the greater the percentage of older male ducks. Those are independent premises that lead to the conclusion, which is the last sentence. I can’t think of the LSAT giving you a “must be true” question based on a flawed argument, unless the answer just repeated one of the premises. Hope this helps! Feel free to ask any other questions that you might have.

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