The author uses the word "immediacy" (line 39) most likely in order to express

Mehran on January 5, 2018

You want to be on the lookout for both conditional statements and the keyword indicators.

"Don't just negate" means that you cannot negate the sufficient condition to conclude the necessary condition does not exist.

Let's take a look at the example we use, "All carrots are vegetables."

I cannot say "not carrot" to conclude "not vegetable."

That would be just negating and that is an invalid argument, i.e. what if I had some celery?

Remember, there are only two ways validly apply an S & N statement:

(1) invoke S to conclude N
(2) inoke the S of your contrapostive to conclude the N of your contrapostive

Jashie on January 5, 2018

Also example 4 of "dont just negate", could you explain more in depth for me? The explaination confused me

Mehran on January 5, 2018

That is correct. Invoking necessary to conclude sufficient refers to "don't just reverse."

Lgguyden on January 5, 2018

I assume the "don't just negate" statement relates to not invoking a "necessary" condition to conclude a "sufficient" condition.

Jashie on January 7, 2018

May sound silly, but the use of this term to invoke, throws me off. Could you describe to me what exactly happens when we invoke a condition?

Mehran on January 8, 2018

No such thing as a silly question! Only silly answers and we promise to keep those to a minimum.

"Invoke" basically just means that the condition exists.

So for example:

A ==> B
not B ==> not A

This is a conditional statement. It only applies if (1) A exists or (2) B does not exist.

So when we say "invoke the sufficient condition," we mean that A exists.

Similarly, when we say "invoke the sufficient condition of the contrapositive," we mean that B does not exist.

Hope that helps! Please let us know if you have any other questions.