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kensJuly 6, 2020
S&N general questions
Can someone please explain the following:
1. confuses a necessary condition for a sufficient condition
2. confuses a sufficient condition for a necessary condition
If A is necessary for B to occur, then A has to exist. If A is sufficient for B to occur, then it is not necessary that A exist because some other variables may be sufficient for the occurence of B? Is this correct way to understand S and N? I still don't quite grasp the underlying concept. Please help and thanks in advance!
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Thanks for the question! So technically, both of these flaws are logically equivalent. Confusing a necessary condition for a sufficient condition is basically a mistaken reversal, in other words
A—>B Conclusion: B—>A
Whereas confusing a sufficient condition for a necessary condition is a mistaken negation, which is
A—>B Conclusion: ~A—>~B
Obviously, both of these statements are contrapositives of each other and so logically equivalent. But there is technically a difference; I can’t think of any questions that make you actually know the difference though.
In a statement like
A—>B? “A” is called the sufficient condition because it is “sufficient” to trigger the necessary condition. Consider:
If it rains, I’ll bring my umbrella.
This means that if it rains, regardless of whatever else is going on, I’ll bring my umbrella. The mere fact that it is raining is enough (is sufficient) to trigger me bringing my umbrella.
B is called the necessary condition because it is “necessary” for the sufficient condition’s truth. In the example above, say I didn’t bring my umbrella. That means it couldn’t have rained, because had it rained, I would’ve brought my umbrella. But I didn’t actually bring my umbrella, which means it didn’t rain. o
Hope this helps! Feel free to ask any other questions that you might have.
