How to Negate Conditional Statements when approaching Necessary Assumption Answer Choices?

[awesomefun2010]

Hi!

I am really struggling with how to negate conditional statements when they appear in the answer choices of necessary assumption questions.

For instance, a few that appeared in recent LSATs.

PT71 S1 Q22: Answer Choice E: Any pricing practice that does not result in unreasonable prices should be acceptable.

The Powerscore Logical Reasoning Bible says to add a "not" to negate, but I'm not sure where to add the not. Also, does any turn into some?


PT73 S4 Q26: Many farmers will not grow green manure unless they abandon the use of chemical fertilizers.

PT77 S4 Q26: (wrong answer choice): Sea Creatures have rarely if ever, wreaked ecological havoc in a new habitat unless they have been able to survive in that habitat after having been deposited by oceangoing ships.

Each time I struggle with such answer choices because I am unsure of how to negate them.

Thanks!

[Adam Tyson]

That's a struggle shared by many, awesomefun2010. The simplest way I know to think of negation is to simply say "that's not true" in response to the answer you are testing. That's all negation is - it's denying the truth of the answer choice.

How that applies to a conditional answer is to say "the thing that this answer says is necessary is not actually necessary." We don't have to go so far as to say the necessary condition in the answer cannot occur. We only need to say "we don't need that."

To use your examples:

1. "Any pricing practice that does not result in unreasonable prices should be acceptable." Negation - those practices might not be acceptable even if they don't result in unreasonable prices.

2. "Many farmers will not grow green manure unless they abandon the use of chemical fertilizers." Negation - they could grow green manure even if they don't abandon chemical fertilizers. They don't have to abandon them in order to do that. Maybe few or none will abandon them.

3. "Sea Creatures have rarely if ever, wreaked ecological havoc in a new habitat unless they have been able to survive in that habitat after having been deposited by oceangoing ships." Negation - they might frequently cause that havoc even if they don't survive.

Deny the truth of the answer. Start with just saying "no, that's not true," and then see where that takes you. You may have to do some rearranging of the words, and the phrase "even if" comes in very handy in that process, but the exact wording is less important than the result.