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

Kenji on April 23, 2020

S&N diagramming

Are both these statement either or statement and are they the only ones? 1. not P---->R, not R--->P (either P or R or both) 2. P--->not R, R---->not P (either P or R or but not both) I always thought we look at the right side of the diagram to conclude whether a statement indicates both or not both, is this correct? Is there a situation where both sufficient and necessary is negated? for example, not P--->not R, R--->P? Thank you.

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Ben on April 23, 2020

Hi Kenken, thanks for the question.

The top statement is either or, while the second statement is either or, but not both.

The first statement is correctly diagrammed, however the second is incomplete.

Because we must show that one of the two must occur when we say "either P or R but not both", we must also note that

not P --> R, and not R --> P

This still holds in addition to what you have (P -> not R, and R -> not P)

As for a situation that has both sufficient and necessary negated. There is no special indicator or formation that would lead to this. It would simply be phrased with both the sufficient and necessary terms negated.

E.g. If I do not play music, I will not hear my favourite song.


I hope this helps. Please let me know if you'd like me to elaborate further.