Conditional imperfection

[Amy West]

On 11/21/13 12:00 AM, Automatic digest processor wrote:
>   "I'm with Doug on this one," my wife offered. In a casual,
>      dinner-table conversation, I shouldn't have taken Doug's /if and
>      only if/ in this technical sense.
>
>      Technical sense? This was my first inkling that there was more than
>      one sense!
>
>
>      http://literalminded.wordpress.com/2013/11/15/conditional-imperfection/
>
>
>
> Is this new to anyone else?
Unless the listener/reader has taken a logic course, they are likely to
re-analyze it as "if, and only if," (especially if it's a phrase they
hear first) so, yes, just as an emphatic. I had, in fact, forgotten that
there was a technical sense until you posted. (I have done minimal logic
in the context of philosophy survey and composition courses.)

Are any of the following defs. of "if" from MWC11 for the technical sense?:

1 a : in the event that b : allowing that c : on the assumption that d :
on condition that
2 : WHETHER <asked if the mail had come> <I doubt if I'll pass the course>
3 — used as a function word to introduce an exclamation expressing a
wish <if it would only rain>
4 : even though : although perhaps <an interesting if untenable argument>
5 : and perhaps not even <few if any changes are expected> — often used
with not <difficult if not impossible>

I'm betting it's 1b or 1d. But it doesn't have a usage label of _logic_,
does it?

There's no entry for "if and only if" in MWC11, so again, no signal to a
consultant that there is a technical sense.

Interestingly enough, there is an entry for the abbreviation that I saw
one of your commenters use, "iff", in MWC11, and it's expanded and has a
geometry verbal illustration. But, again, there's no own place entry to
tell the reader that it has a specific logical meaning.

---Amy West

(And tangential to this, yes, I know someone who identifies as an
atheist Jew.)

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