Article View: sci.logic
Article #519implication truth table
From: cmitchell
Date: Mon, 16 Nov 1992 21:27
Date: Mon, 16 Nov 1992 21:27
54 lines
2096 bytes
2096 bytes
Greetings - I'm doing a first course in real analysis and have a question about the implication relation. I've asked 3 professors and checked 3 text books so far and have no satisfying answer. Truth Table for `A implies B' (If A Then B): A B -> F F T F T T T F F T T T Consider the following sentence: IF it is sunny tomorrow, THEN I will go to the ball game. My expectation was that: if it is not sunny, then I would have no way of determining the truth of the implication. My question is: WHY is the implication relation defined as it is? My best speculations so far are: 1- because it gives us an internally consistent system. (this seems like the easy way out to me, but what do I know?) 2- my expectation (above) seems to have a temporal assumption within it (a kind of cause and effect?). this would seem contrary to the spirit of what is intended when a mathematician speaks in terms of IF-THEN, but I can get no farther with this line of reasoning on my own. 3- there are simply differences between the language of Math and the language of English and mathematicians have agreed to speak Math to one another. I suppose this would hearken back to number 1. 4- the accepted definition allows implications like A->B->C to have an intuitively satisfying interpretation. (again this seems arbitrary rather than reasoned). Thanks in advance for any responses. -- "The opinions and views expressed here are strictly my own and do not necessarily reflect the official position of either the U.S. Air Force or its contractors."
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Path: arc1-ca.pugleaf.net!sparky!uunet!charon.amdahl.com!pacbell.com!sgiblab!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!udecc.engr.udayton.edu!blackbird.afit.af.mil!falcon.aamrl.wpafb.af.mil!cmitchell From: cmitchell@falcon.aamrl.wpafb.af.mil Newsgroups: sci.logic Subject: implication truth table Message-ID: <1992Nov16.162733.1831@falcon.aamrl.wpafb.af.mil> Date: 16 Nov 92 16:27:33 EST Organization: USAF AL/CFH, WPAFB, Dayton, OH Lines: 55