Talk:Paradoxes of material implication

message: I don't think there can be any real objection to the merge, although it is not obvious which title the merged article should have. — Charles Stewart (talk) 09:05, 9 March 2009 (UTC)
replies: text: Merge done, from Paradox of entailment (Talk:Paradox of entailment) to here.  — Charles Stewart (talk) 13:17, 20 March 2009 (UTC)
thread_title: Merge with [[Paradox of entailment]]

message: This article needs:
#Cleaning up: the merge I did isn't ghastly, but it's not really tidy either.  The article would probably read better if the PofE was used, both formally and informally, in the lede, and the alternatives were introduced in the supporting sections.
#The article needs a proper introduction to strict implication, after all these paradoxes were what led to that formulation.
#There are some (one in the present list) PofMIs that are not valid in non-truth-functional intuitionistic logic.  This is worth including, since it illuminates what a logical theory needs to support material implication. — Charles Stewart (talk) 13:27, 20 March 2009 (UTC)
thread_title:  TLC needed 

message: "(P & Q) -> R" does not correctly represent the logic of two switches wired in series. It is true that if both switches are on, the light will come on. Thus, (P & Q) is indeed a sufficient condition for R: "If (P & Q), then R". However, it is also the case that both must be on, and so it is a necessary condition as well: "If R, then (P & Q)". Thus, the correct formula is the biconditional "(P & Q) if and only if R": "(P & Q) <-> R", not "(P & Q) -> R".  — Doug Shaver—Preceding unsigned comment added by Doug Shaver (talk • contribs) 14:59, 27 June 2010 (UTC)
replies: text: Doug, "(P & Q) -> R" is a correct (i.e. true) statement about two switches in series.  It is also true about two switches in parallel.  I think you are confusing specificity with correctness.  The inference "(P & Q) -> R, therefore either P -> R or Q -> R" gives valid results in the parallel case but invalid results in the series case.  Besides, "(P & Q) <-> R" implies "(P & Q) -> R" which still implies "P -> R or Q -> R", so your more specific formulation does NOT escape the paradox. Howard Landman (talk) 02:08, 5 December 2010 (UTC)
thread_title:  Switches in series 

message: Hermione: "I'm sorry, but that's completely ridiculous! How can I possibly prove that [the Ressurection Stone] doesn't exist? mean, you could claim that anything's real if the only basis for believing in it is that nobody's proved it doesn't exist!"
Mr. Lovegood: "Yes, you could. I am glad to see that you are opening your mind a little." 
-J. K. Rowling  —Preceding unsigned comment added by 74.96.158.81 (talk) 02:31, 27 July 2010 (UTC)
thread_title:  Interesting reference 

message: The discussion of the "paradox of entailment" in this article is incorrect. The "paradox of entailment" consists of a conditional in which the antecedent is a contradiction. The conditional is true regardless of the truth value of the consequent. In case the consequent is false, this can appear paradoxical. No deduction is involved. Modus ponens cannot apply to such a conditional because the antecedent is false. In this discussion, a seemingly paradoxical conditional is presented and modus ponens is implicitly, but incorrectly, appealed to in order to justify a manifestly false deduction. I hope that whoever is responsible for this section will correct it.
Dagme (talk) 19:44, 2 January 2011 (UTC)
thread_title:  The discussion of the "paradox of entailment" in this article is incorrect. 

message: This is not related to the principle of explosion.  It is the principle of explosion.
Who calls this property "the paradox of entailment"?  If it's a common name, I've never heard it.  Can we at least have a citation for this? Phiwum (talk) 02:32, 23 October 2016 (UTC)
thread_title:  Paradox of entailment 

message: Is different levels - syntactic (implication), semantic (inference), pragmatic. The paradoxes exist when we give from semantic into syntactic "machine" wrong information. And we get wrong information back. I was taught that way. Constantinehehe 12:22, 11 December 2019 (UTC)
thread_title:  MY personal hunch