Select the answer choice that correctly diagrams the following Sufficient & Necessary statement:Harry could never...
ehayJuly 12, 2019
Introducing sufficient/necessary conditions
The explanation says that unless introduces necessary conditions, and gave instructions about negating other parts, but Ive never heard of these connectives introducing sufficient or necessary conditions.
I learned that when unless is in a conditional, the part following unless is the antecedent. You negate the antecedent and symbolize it. Then I did the contraposition of that.
Ex. P unless Q
= -Q > P (symbolization)
Can you explain how I can connect yalls explanation with the way I learned. You guys explain introduction of suff/nec conditions, but most of my understanding starts with identifying antecedents and consequent then translating based on the connective. (And sufficient conditions where antecedents and necessary conditions where consequents.)
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You can also think of "unless" as meaning "if not," and the key thing to remember here is that you're negating the sufficient condition. The way that you learned to diagram "unless" statements means the same thing as what our curriculum teaches, but it's just diagramming it in the contrapositive.
In this question, let's show how you can diagram this statement using different strategies and still come up with the same answer.
Harry could never have defeated Voldemort unless he was the chosen one.
Let's pick the first part of the sentence, negate it, and make it the sufficient condition.
DV - >CO
Now let's try negating the second part of the sentence, make it the sufficient condition, and then make the first part of the sentence the necessary condition.
/CO - >/DV
This is the same thing (it's the contrapositive of the first statement).
What matters is that whatever part of the sentence you put in the sufficient condition, it needs to be negated.
Does this make sense? Let us know if you have any other questions!
