Roses always provide a stunning display of color, but only those flowers that smell sweet are worth growing in a gard...

Shirnel March 31, 2020

Use of quantifiers

In the case of this question (as well as in the learning video) I noticed that after making the first deduction, that deduction is then used as the quantifier with the second S&N premised to make a deduction. Is that always the case? This is how I approached this question: Roses always provide a stunning display of color R==>SDC not SDC ==> not R but only those flowers that smell sweet are worth growing in a garden. WG==SS not SS==> not WG Some roses have no scent. R - some - not ss not ss - some - R Deduction 1 not ss - some - R==>SDC not ss - some - SDC or SDC -some - not ss Deduction 2 R - some - not ss==>not WG R - some - not WG or not WG - some R Now I understand that the answer came from using the reversal of the Deduction 1 So there's a 3rd deduction: SDC - some - not ss==>not WG SDC - some - not WG For strategic purposes, after I make one valid deduction with a quantifier, should I always use it as my first step using that deduction to make another valid deduction from the S&N premises?

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SamA April 3, 2020

Hello @Shirnel,

This is a very thorough diagram of this question, and your logic is valid. The problem is that you may not have time to diagram everything you have here when under test conditions. As you demonstrated, there are a few conclusions that can be drawn, but only one is going to appear in an answer choice. I would make one or two deductions that I predict to be important, and then turn to the answer choices. Here is how I approached this one.

R ---> SDC
not SDC ---> not R

WG ---> SS
not SS ---> not WG

R --- some --- not SS ---> not WG

I would have stopped here, because I am able to see some important relationships between these conditions. I've made some important connections, but I won't write every deduction. While you are practicing, it is great that you are so thorough with these deductions. This will help you improve your understanding of sufficient and necessary reasoning. Eventually, however, you should be able to make these conclusions without writing them all down.

Elza-Hovhannisyan September 8, 2020

I understand how you got to R --- some --- not SS ---> not WG

However I interpret answer choice A as follows SDC ---> not WG
A: Some flowers which provide a stunning display of color are not worth growing in a garden.

I have also indicated R ---> SDC and I believe I cannot reverse that to say SDC ---> R

Would you please explain how answer choice A in interpreted as
R --- some --- not SS ---> not WG