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Turning the necessary condition into words, How should I say it??

psbrathwaitepsbrathwaite Legacy Member
edited June 2014 in General 207 karma
I have a problem turning the necessary condition into words sometimes.
For example, the sufficient condition reads well:

Zombies attacking the city makes it sufficient for me to know the market will sink.
Z -> S

But for the necessary:

the market sinking is necessary for me to know that zombies attacked?
The market sinking is necessary for zombies to attack the city?
or maybe

It's necessary for the market to sink if zombies attack the city?

How do I make this into English correctly?


  • Will EdwardsWill Edwards Alum Member Inactive Sage
    175 karma
    You could say,
    If zombies attack the city, the market will necessarily sink.

    But I think what you are after is somewhat elusive.
    The sufficient and necessary conditions are like the subject and the predicate. You need both to have a real sentence/statement. How you word it is just semantics.

    In the end, I would recommend leaving the statement as you find it, or simplifying it to an if/then type of statement and not trying to make different statements for the sufficient and the necessary.
  • chrijani7chrijani7 Alum Member
    edited June 2014 827 karma
    Before I begin, I don't know if my answer is 100% accurate but this is my take on it.

    Using the word necessary, here is an example(s) I could think of:
    It is necessary for the market to be sinking for the zombies to attack
    For the zombies attack to occur, it is necessary that the market sink.

    Keep in mind the sentence does not have to follow sufficient --> necessary, it could bring out the necessary condition followed by the sufficient but then would be diagrammed sufficient --> necessary. As the example above shows the necessary comes before the the sufficient but would be diagrammed S--> Z

    However,I think you are looking for words like necessary and sufficient as indicators in the sentence when wording it. However, for your example it seems to work for the sufficient example, but becomes somewhat "sloppy" with the necessary wording. It does not have to have the words necessary/sufficient to make the relationship

    Try and think of it in terms of words that indicate a necessary condition, for instance MUST. For example:

    The zombies attacked, so the market MUST be sinking.

    Some more words that indicate necessary conditions are:
    Only if
    Only where
    Only when

    There are more, as well as some where you can negate/necessary (from 7sage lessons).
  • vandyzachvandyzach Member
    358 karma
    When I see that something is a necessary condition, I think to myself "Ok, I know this is necessary- what is it necessary for? And then if it's an "unless statement", you know it is necessary for the negation of the sufficient (the part of the statement that's not the necessary!).

    Hope that helps!
  • Will EdwardsWill Edwards Alum Member Inactive Sage
    175 karma
    This may seem like it is splitting hairs, but you have to be very careful with the tenses here.

    "If zombies attack the city, then the market will sink,"
    "It is necessary for the market to be sinking for the zombies to attack"
    do NOT say the same thing.
    One has as a necessary condition "market will sink," the other "market is (already) sinking."
    It's tricky because necessary condition does not mean the same as necessary for, if that makes sense. Another way to say it is that the necessary condition does not always precede the sufficient condition.

    A couple of examples:

    If you break the law, you will get arrested. - Necessary condition follows sufficient in time. Getting arrested is not necessary for breaking the law, but it is the necessary condition here. (This is not true in real life of course).

    You can get it if you really want it. - Again necessary condition follows sufficient condition in time. You really want it first, then you can get it (after you try, try and try).

    Making an omelet requires eggs. - Necessary condition precedes sufficient in time. You must posses eggs first in order to make an omelet.
  • chrijani7chrijani7 Alum Member
    827 karma
    @WillEdwards Great explanation!
  • Will EdwardsWill Edwards Alum Member Inactive Sage
    175 karma
    Thanks! Glad it was helpful.
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