# Conditional imperfection

Neal Whitman nwhitman at AMERITECH.NET
Thu Nov 21 17:12:47 UTC 2013

```Indeed I do remember that talk. I remember you illustrating entailments with Venn diagrams. One had A as a subset of P; one had P as a subset of A; all this so you could get a laugh when you casually talked about "whether A-ness implies P-ness, or P-ness implies A-ness."

Neal

________________________________
From: Laurence Horn <laurence.horn at YALE.EDU>
Sent: Thursday, November 21, 2013 10:59 AM
Subject: Re: Conditional imperfection

...
Certainly "only if", by virtue of its presupposition, is a lot closer to "if and only if" than simple "if" conditionals are.  Even though we often move from e.g. "If you mow the lawn I'll give you \$5" to "If and only if you mow the lawn I'll give you \$5" (Geis & Zwicky's "invited inference", which Neal will recall my discussing at OSU at a talk in Arnold's honor back in the previous millennium), this if-->iff "conditional perfection" (whence Neal's subject line) amounts to a context-dependent implicature rather than a presupposition and is much easier to slough off.

LH

On Nov 20, 2013, at 11:50 PM, Neal Whitman wrote:

> From my latest blog post:
>
>   "You're a Jew," Doug said, "if and only if you believe in God!"
>   ...
>
>   "So ... Muslims are Jews?" I asked.
>
>   "No, Dad," Doug explained. He then summarized for me the concept of
>   /only if/, concluding, "You've out-literaled yourself!"
>
>   Later on, I drew a truth table for /if/ and one for /only if/, and
>   showed them to Doug. He found that, after all, he and I agreed about
>   the meaning of /only if/. So what's the difference between /only if/
>   and /if and only if/, I asked.
>
>   "I don't think there is one," Doug said.
>
>   I drew up the table for /if and only if/, and Doug understood it,
>   but in his opinion, in ordinary conversation, /if and only if/ was
>   just an emphatic way of saying "only if".
>
>   "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?
>
> Neal
>
> ------------------------------------------------------------
> The American Dialect Society - http://www.americandialect.org

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