You are viewing an obsolete version of the DU website which is no longer supported by the Administrators. Visit The New DU.
Democratic Underground Latest Greatest Lobby Journals Search Options Help Login

Reply #102: "The relationship between validity and truth depends upon one's definitions for each" [View All]

Printer-friendly format Printer-friendly format
Printer-friendly format Email this thread to a friend
Printer-friendly format Bookmark this thread
Home » Discuss » Topic Forums » September 11 Donate to DU
SDuderstadt Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Jun-10-08 06:04 PM
Response to Reply #96
102. "The relationship between validity and truth depends upon one's definitions for each"
Edited on Tue Jun-10-08 06:06 PM by SDuderstadt
Wtf? We're talking about Logic, mhatrw. Your initial answer is made even more puzzling by your second sentence which, I suspect, you've cut and pasted from some Logic website and is essentially correct. Validity in Logic refers to structure and truthfulness is referred to as soundness. So, an argument, much as you describe, can be valid, in that it follows proper for, yet still not be sound (or true) because one or more of the premises are flawed. For example (and I am going to use a purposefully imflammatory example on purpose):

All "truthers" are stupid.
So-and-so is a "truther".
Therefore, So-and-so is stupid.

Valid, but not sound. Valid in that it follows the form:

All A is B
C is A
Therefore, C is B.

The argument is unsound (untrue) because the first premise is not true. All "truthers" are not just seems that way.

Are far as your "question", it's because its antecedent is the negated consequent of its converse. Duh. I wouldn't waste a lot of time "testing" me on contraposition, mhatrw. I'm pretty sure I know far more about logic than you do, especially since I had to ask you my question numerous times over a long period of time before you could answer.
Printer Friendly | Permalink | Reply | Top

Home » Discuss » Topic Forums » September 11 Donate to DU

Powered by DCForum+ Version 1.1 Copyright 1997-2002
Software has been extensively modified by the DU administrators

Important Notices: By participating on this discussion board, visitors agree to abide by the rules outlined on our Rules page. Messages posted on the Democratic Underground Discussion Forums are the opinions of the individuals who post them, and do not necessarily represent the opinions of Democratic Underground, LLC.

Home  |  Discussion Forums  |  Journals |  Store  |  Donate

About DU  |  Contact Us  |  Privacy Policy

Got a message for Democratic Underground? Click here to send us a message.

© 2001 - 2011 Democratic Underground, LLC