From MorphemeAddict@wmconnect.com Sat Jul 31 05:10:49 2004 Received: with ECARTIS (v1.0.0; list lojban-list); Sat, 31 Jul 2004 05:10:49 -0700 (PDT) Received: from imo-d21.mx.aol.com ([205.188.144.207]) by chain.digitalkingdom.org with esmtp (Exim 4.32) id 1BqshF-0000Y2-TM for lojban-list@lojban.org; Sat, 31 Jul 2004 05:10:42 -0700 Received: from MorphemeAddict@wmconnect.com by imo-d21.mx.aol.com (mail_out_v37_r2.6.) id d.1e0.26b49dff (25508) for ; Sat, 31 Jul 2004 08:10:05 -0400 (EDT) From: MorphemeAddict@wmconnect.com Message-ID: <1e0.26b49dff.2e3ce61d@wmconnect.com> Date: Sat, 31 Jul 2004 08:10:05 EDT Subject: [lojban] jimpe: logic example To: lojban-list@lojban.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_1e0.26b49dff.2e3ce61d_boundary" X-Mailer: 6.0 sub 12 X-archive-position: 8366 X-ecartis-version: Ecartis v1.0.0 Sender: lojban-list-bounce@lojban.org Errors-to: lojban-list-bounce@lojban.org X-original-sender: MorphemeAddict@wmconnect.com Precedence: bulk Reply-to: lojban-list@lojban.org X-list: lojban-list --part1_1e0.26b49dff.2e3ce61d_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 2004-07-31 5:21:21 AM Eastern Daylight Time, ecartis@digitalkingdom.org writes: > > Unless I'm completely screwing something up, it's deducing the _negation_ > of > > a > > premise from the _negation_ of a consequence, which is perfectly valid > logic. > > It's called "modus tollens" or the "rule of the contrapositive". > > There's nothing wrong with the logic. The use of "premise" here > is not standard though. An implication has an antecedent and a > consequent, a logical argument has premises and conclusion. > > In a modus tollens type of argument, one of the premises is an > implication and the other premise is the negation of the consequent > of that implication. From those two premises, it is valid to > conclude the negation of the antecedent of the implication. > > mu'o mi'e xorxes > Okay. It looked funny to me, but I haven't done formal logic in a very long time. Thanks for taking another look at it. stevo --part1_1e0.26b49dff.2e3ce61d_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable In a message dated 2004-07-31 5:21:21=20= AM Eastern Daylight Time, ecartis@digitalkingdom.org writes:


> Unless I'm completely=20= screwing something up, it's deducing the _negation_ of
> a
> premise from the _negation_ of a consequence, which is perfectly va= lid logic.
> It's called "modus tollens" or the "rule of the contrapositive".

There's nothing wrong with the logic. The use of "premise" here
is not standard though. An implication has an antecedent and a
consequent, a logical argument has premises and conclusion.

In a modus tollens type of argument, one of the premises is an=20
implication and the other premise is the negation of the consequent=20
of that implication. From those two premises, it is valid to=20
conclude the negation of the antecedent of the implication.

mu'o mi'e xorxes

Okay.  It looked funny to me, but I haven't done formal logic=20= in a very long time.  Thanks for taking another look at it.

stevo --part1_1e0.26b49dff.2e3ce61d_boundary--