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Daily Drills 44 - Section 44 - Question 3

P: People who are red/green color-blind cannot distinguish between green and brown.P: Gerald cannot distinguish betwe...

Boxingbest October 12, 2016

Confused

Okay I'm very confused. Every aspect is met, why is it not A?

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Mehran October 14, 2016

@Boxingbest (A) is concluding the sufficient condition of your general principle.

This can never be a valid deduction. Remember, we invoke the sufficient condition to conclude the necessary condition.

"People who are red/green color-blind cannot distinguish between green and brown."

P1: RGCB ==> not D
D ==> not RGCB

P2: not D

C: No Valid Conclusion

"not D" is our necessary condition. It does not allow you to properly conclude anything else.

Remember, don't just reverse!

Hope this helps! For a more in-depth discussion of these concepts, please watch our video lesson on Sufficient & Necessary conditions.