From lojban-beginners+bncCML0xpmUARD0kezeBBoEobHQGg@googlegroups.com Fri Apr 30 09:44:53 2010 Received: from mail-wy0-f189.google.com ([74.125.82.189]) by chain.digitalkingdom.org with esmtp (Exim 4.71) (envelope-from ) id 1O7tKY-0003J1-Gl; Fri, 30 Apr 2010 09:44:52 -0700 Received: by wyb36 with SMTP id 36sf253594wyb.16 for ; Fri, 30 Apr 2010 09:44:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=beta; h=domainkey-signature:received:x-beenthere:received:received:received :received:received-spf:received:mime-version:received:received :in-reply-to:references:date:message-id:subject:from:to :x-original-authentication-results:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :sender:list-subscribe:list-unsubscribe:content-type; bh=nOpz1PU01OTaCQ1xI/gNdamadIN3K2sMqyKOamPb+P4=; b=NyA1ZWsWoSKndegTK5bV9gUAGLBY4tsz4VbPE77sxBx5mSUqAxP/wBy+RbfiSpRg23 zJQgYCHIqIxZ1z5w1hS3l5kYfWfnDhqPdtnCIkONE/SmOzfc6Ww82F7Sd1xqPiwMR1TU Wnppjm9wTcDEQiNCVq7yaev5nEgxCgN65oSVA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlegroups.com; s=beta; h=x-beenthere:received-spf:mime-version:in-reply-to:references:date :message-id:subject:from:to:x-original-authentication-results :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type; b=eb49nOhOx2q9mMdKbjm8XihqOobll9LcRmfLdZSgCiIMADtCzUpzqb5SGxmp8joBB4 +mVkucCxSMQhzMO0UpM9U5uQbwIAR2pYjGZpokxjeBwQGigBC8zCfnGksc5ZCW8xxmUx Bmae6skLAfMXVZBOmefLpIc2+TRhTGfxVCCrM= Received: by 10.223.5.69 with SMTP id 5mr2998494fau.37.1272645876845; Fri, 30 Apr 2010 09:44:36 -0700 (PDT) X-BeenThere: lojban-beginners@googlegroups.com Received: by 10.213.59.76 with SMTP id k12ls16044510ebh.3.p; Fri, 30 Apr 2010 09:44:35 -0700 (PDT) Received: by 10.213.56.8 with SMTP id w8mr137222ebg.8.1272645874742; Fri, 30 Apr 2010 09:44:34 -0700 (PDT) Received: by 10.213.56.8 with SMTP id w8mr137221ebg.8.1272645874693; Fri, 30 Apr 2010 09:44:34 -0700 (PDT) Received: from mail-vw0-f53.google.com (mail-vw0-f53.google.com [209.85.212.53]) by gmr-mx.google.com with ESMTP id 11si134068ewy.9.2010.04.30.09.44.33; Fri, 30 Apr 2010 09:44:33 -0700 (PDT) Received-SPF: pass (google.com: domain of blindbravado@gmail.com designates 209.85.212.53 as permitted sender) client-ip=209.85.212.53; Received: by vws13 with SMTP id 13so50226vws.40 for ; Fri, 30 Apr 2010 09:44:32 -0700 (PDT) MIME-Version: 1.0 Received: by 10.220.127.81 with SMTP id f17mr7677238vcs.133.1272645872340; Fri, 30 Apr 2010 09:44:32 -0700 (PDT) Received: by 10.220.167.142 with HTTP; Fri, 30 Apr 2010 09:44:32 -0700 (PDT) In-Reply-To: References: <4BD94677.6060909@lojban.org> Date: Fri, 30 Apr 2010 12:44:32 -0400 Message-ID: Subject: Re: [lojban-beginners] Conditionals--da'i etc. From: Ian Johnson To: lojban-beginners@googlegroups.com X-Original-Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of blindbravado@gmail.com designates 209.85.212.53 as permitted sender) smtp.mail=blindbravado@gmail.com; dkim=pass (test mode) header.i=@gmail.com X-Original-Sender: blindbravado@gmail.com Reply-To: lojban-beginners@googlegroups.com Precedence: list Mailing-list: list lojban-beginners@googlegroups.com; contact lojban-beginners+owners@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: Sender: lojban-beginners@googlegroups.com List-Subscribe: , List-Unsubscribe: , Content-Type: multipart/alternative; boundary=0016e68e8ba5254ecd048576f5d4 --0016e68e8ba5254ecd048576f5d4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable So this is about inference from an assumption, not the classical implication, which is *defined* so that the statement ~p v q <-> p -> q is true. In other words nibli does not exclusively involve truth values of propositions, but rather also involves the ability to actually deduce something from something else, whereas the classical implication does (whatever the truth value of ~p v q is, the truth value of p -> q is the same, because then whenever p is true q must be true). That was what I was trying to get at. And Luke: I was just constructing a nonsense proposition to be my antecedent. 2010/4/30 Jorge Llamb=EDas > On Fri, Apr 30, 2010 at 11:01 AM, Ian Johnson > wrote: > > So nibli is not defined using the classical implication, then? > > "nibli" says that x2 logically follows from x1. Material implication > is something different. > > >Because in > > the classical implication "pigs can fly implies that the sky is green" = is > > (assuming that we haven't done something really bizarre to the > pigs) true. > > Right "ganai lo xarju cu vofli gi lo tsani cu crino" is true, given > that "lo xarju cu vofli" is false. (This "implies" does not mean > "logically entails".) > > It doesn't mean that you can infer "the sky is green" just from "pigs > can fly". The valid inference you can make is the following: > > (True) premise: ganai lo xarju cu vofli gi lo tsani cu crino > (False) premise: lo xarju cu vofli > Conclusion: lo tsani cu crino > > That's a valid inference. But since one of the premises is false, we > can't say that the conclusion is true. The valid inference is thus: > > lo du'u ge ganai lo xarju cu vofli gi lo tsani cu crino gi lo xarju cu > vofli cu nibli lo du'u lo tsani cu crino > > But you need both premises in order to infer the conclusion. > > mu'o mi'e xorxes > > -- > You received this message because you are subscribed to the Google Groups > "Lojban Beginners" group. > To post to this group, send email to lojban-beginners@googlegroups.com. > To unsubscribe from this group, send email to > lojban-beginners+unsubscribe@googlegroups.com > . > For more options, visit this group at > http://groups.google.com/group/lojban-beginners?hl=3Den. > > --=20 You received this message because you are subscribed to the Google Groups "= Lojban Beginners" group. To post to this group, send email to lojban-beginners@googlegroups.com. To unsubscribe from this group, send email to lojban-beginners+unsubscribe@= googlegroups.com. For more options, visit this group at http://groups.google.com/group/lojban= -beginners?hl=3Den. --0016e68e8ba5254ecd048576f5d4 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable So this is about inference from an assumption, not the classical implicatio= n, which is defined so that the statement ~p v q <-> p -> q= is true. In other words nibli does not exclusively involve truth values of= propositions, but rather also involves the ability to actually deduce some= thing from something else, whereas the classical implication does (whatever= the truth value of ~p v q is, the truth value of p -> q is the same, be= cause then whenever p is true q must be true). That was what I was trying t= o get at.

And Luke: I was just constructing a nonsense proposition to be my antec= edent.

2010/4/30 Jorge Llamb=EDas <jjllambias@gmail.com= >
On Fri, Apr 30, 2010 at 11:01 AM, Ian Johnson <blindbravado@gmail.com> wrote:
> So nibli is not defined using=A0the classical implication, then?

"nibli" says that x2 logically follows from x1. Material im= plication
is something different.

>Because in
> the classical implication "pigs can fly implies that the sky is g= reen" is
> (assuming that we haven't=A0done=A0something really bizarre to the= pigs)=A0true.

Right "ganai lo xarju cu vofli gi lo tsani cu crino" is tru= e, given
that "lo xarju cu vofli" is false. (This "implies" does= not mean
"logically entails".)

It doesn't mean that you can infer "the sky is green" just fr= om "pigs
can fly". The valid inference you can make is the following:

(True) premise: ganai lo xarju cu vofli gi lo tsani cu crino
(False) premise: lo xarju cu vofli
Conclusion: lo tsani cu crino

That's a valid inference. But since one of the premises is false, we can't say that the conclusion is true. The valid inference is thus:

lo du'u ge ganai lo xarju cu vofli gi lo tsani cu crino gi lo xarju cu<= br> vofli cu nibli lo du'u lo tsani cu crino

But you need both premises in order to infer the conclusion.

mu'o mi'e xorxes

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