Chapter Text, Question #4

[buyer3700]

In this sample question about the earth's rotation and the moons...

I diagramed it:

AS GI for sentence 2, but for sentence 3, I used the without rule to negate the sufficient condition like this

PCE=unstable to support life, or no life, I used L with a slash through it or PCE with a slash using the books example. So using the without rule, as we negate the sufficient condition it becomes PCE AS GI

I used L(life) AS GI

I got the answer right and for all the right reasons. So all I can think it that PCE with a slash is the same as my L without a slash?

PCE=no life is the same as my L slash? So my L would = PCE slash?

Does this make any sense?

[Steve Stein]

Thanks for your question. Your diagram does make sense--presuming that every planet without that climate issue is capable of supporting life. While that presumption works in this case, it is more precise to say that the climate is not too extreme for the planet to support life (because life might be precluded by some other factor).

Tricky and subtle concept--let me know whether that makes sense--thanks!

~Steve

[buyer3700]

Steve,

Thank you for the response. Yes and no re: "does it make sense?"

In the logic games bible book we are told to always think in positive terms, it is one more step to take a negative term and then have to worry about another negation.

Moving forward, I want to get the best score possible, how should I do it?

Thanks!

[Steve Stein]

Hi, and thanks for your response. If you'd like to keep that one in the postive, you could phrase it as "life-suitable climate." That might sound like a picky distinction, and you generally have some choice as to how you might characterize such a condition. It can't hurt to err on the side of caution (by sticking more closely to the wording from the stimulus); just keep an eye on your results in conditional reasoning--and in particular, any that happen to give you trouble because of how you chose to characterize the condition.

Let me know whether this is helpful--thanks!

~Steve