Mistaken Reversals in "Parallel Reasoning"

[peregrinus]

Hi,

I've been working on some of these questions from the Logical Reasoning Bible and had one basic question. Take for example the question on pg 407 which features a mistaken negation. Given that mistaken reversals are simply contrapositives of mistaken negations, they are logically equivalent to each other. The book also clearly states that positive or negative nature of the conclusion does not impact logical match in terms of parallel reasoning. Given both these things, isn't a mistaken reversal a perfectly acceptable answer in case the stimulus has a mistaken negation and vice versa?

Much appreciated.

[Nikki Siclunov]

Hi peregrinus,

Great question! Indeed, the Mistaken Negation of a conditional statement is identical in meaning to its Mistaken Reversal: one is the contrapositive of the other. This is something frequently tested in Flaw in the Reasoning questions, where an argument commits a Mistaken Negation and the correct answer describes a Mistaken Reversal. Given that any conclusion in the form of a Mistaken Negation assumes that the MR is true (and vice versa), such descriptions are correct.

In Parallel Reasoning questions, however, you need to identify a pattern of reasoning most similar to that in the argument. If the argument contains a Mistaken Negation, the pattern of reasoning must be in the form of a Mistaken Negation. Same with MR. Although the MN and MR are contrapositives of each other and commit an identical error in reasoning, they are not structurally parallel. In Parallel Reasoning questions, you need to identify an argument that has the exact same structure.

Hope this helps... let me know if it doesn't!