Talk:Denying the antecedent

message: is a double page with Non sequitur (logic), i suggest it should redirect to that page.
:Old, but I'll bite. This is a specific type of non sequitur, but this page (and related pages on logical fallacies) go into more depth than non sequitur (logic) should. —Cuiviénen 20:10, 11 February 2007 (UTC)
replies: text: no. --YbborT 22:11, 19 February 2007 (UTC)

message: Really should win an award for leftist crap (which is saying a lot on Wikipedia)!  — Preceding unsigned comment added by 96.249.195.72 (talk) 20:21, 8 June 2014 (UTC)
thread_title: This is a horrible article!

message: If I have a boyfriend, I will go to the dance tomorrow.
I don't have a boyfriend.
But I can still go to the dance tomorrow.  —Preceding unsigned comment added by 68.101.123.219 (talk) 19:37, 17 February 2008 (UTC)
replies: text: Actually this might be a more relevant and understandable example for the article. 118.90.72.183 (talk) 15:00, 7 June 2008 (UTC)
replies: text: Actually, in DA, it should actually be:
"If I have a boyfriend, I will go to the dance tomorrow.
I don't have a boyfriend.
So I can't go to the dance tomorrow."
64.231.120.29 (talk) 02:19, 14 June 2008 (UTC)

text:  But again, let's get realistic. When a teenage girl says "If I have a boyfriend, I will go to the dance tomorrow," they are implying that they will not go if they don't have such a boyfriend. This is the valid form of denying the antecedent, which I argue should get more play time in this article. Chicopac (talk) 16:47, 25 April 2012 (UTC)
replies: text: No, they are implying no such thing. This article is about logical fallacies, its not a portal to Cyc. -- 96.247.231.243 (talk)  —Preceding undated comment added 06:18, 1 January 2014 (UTC)
thread_title:  well... 

message: The following sentence implies that denying the antecedent is sometimes a valid argument.
:::"Arguments of this form are invalid (except in the rare cases where such an argument also instantiates some other, valid, form). "
It goes on to demonstrate that if an argument of the form "denying the antecedent" is arbitrarily altered by adding some other condition, then the modified argument may be valid, thus proving that there is an exception to the rule that denying the antecedent is fallacious.
The new, randomly introduced argument, is somewhat similar to the original argument, but according to the definition of the form given above, it is not an example of this form.   Therefore, I don't understand how this proves that the first argument, denying the antecedent, was "valid in this case".
I suggest removing the phrase 
:::"(except in the rare cases where such an argument also instantiates some other, valid, form)"
Mark.camp (talk) 12:46, 6 January 2009 (UTC)
replies: text: It didn't say that the form is sometimes valid, it said that some arguments of the form are valid. For example:  "[1] If (R or S), then R. [2] ~(R or S). Therefore, [3] ~R."  That is certainly valid (the conclusion follows from De Morgan's laws and conjunction elimination) even though it denies the antecedent in form. --Atethnekos (Discussion, Contributions) 15:13, 9 May 2012 (UTC)

text: I think the one issue with your example is that it is unclear about the status of your premisses. You say that "Q->P" is an implicit premise. Well, that's fine, but an implicit premise is still a premise, and when you include that premise, you no longer have an argument of the denying the antecedent form, I believe. --Atethnekos (Discussion, Contributions) 02:49, 11 March 2013 (UTC)

text: if it is a bug, then it is an insect -- this premise is false. Deriving a true conclusion from a false premise is trivial, and you have done so here while employing a DA fallacy. Your argument is of the form false -> Q. ~false (i.e., true). Therefore Q. But clearly true -> Q is not a valid argument regardless of whether Q is true (it happens to be, here). There is an inherent implication of "if Q then P" by definition in the predicates -- there is no such "implicit implication" at all. There is a misstated, false, premise, P -> Q, in place of a correct, true, premise, Q -> P. You can't argue that an argument is valid because the valid argument is "inherent" in the meanings of the terms, you have to take the argument as stated. -- 96.247.231.243 (talk) 06:23, 1 January 2014 (UTC)
thread_title: Don't understand the proof that subject form of argument is sometimes valid

message: The article is written like "if" is an implication marker. Which is often isn't, f.ex. imagine an american dialogue:
:Voter: why don't you veto the congress decision?,
:Congress man: If I be president, I could veto the decision, now I'm not, and therefore I can't.
The logic is perfect in the context, where "if" signals equivalence be_president(X) ≡ can_veto(Congress, X) , not implication. Normal language doesn't include such a term as "if and only if", and it does allow ambiguous meanings that are distinguished by context. Only logicians believe that their usage of "if" is the same as implication. ... said: Rursus (mbork³) 13:34, 8 January 2010 (UTC)
replies: text: The article is written like "if" is an implication marker. Which is often isn't -- What an ironic fallacy of denial of the antecedent. No number of examples of non-fallacies using "if" will establish that "if" is not used fallaciously. Numerous common examples abound such as "The police protect us from criminals. If you're doing nothing wrong, you have nothing to fear from the police." -- 96.247.231.243 (talk) 06:51, 1 January 2014 (UTC)
thread_title: "If"?

message: It is unclear why this edit was left in place. It was an nonconstructive addition on or about November 2010, originated from an ip address and was not signed by it's author.
As a general user, seeing this page for the first time I found the reference to be unclear. If it has some purpose in the article, that may need clarification.
If not, shall the link be removed? -Andreis  —Preceding unsigned comment added by 24.156.67.243 (talk) 01:45, 11 March 2011 (UTC)
replies: text: Removed now. —Mrwojo (talk) 04:59, 11 March 2011 (UTC)
thread_title:  God Save the Queen Link 

message: "Denying the antecedent, sometimes also called inverse error or fallacy of the inverse, is a formal fallacy of inferring the inverse from the original statement. It is committed by reasoning in the form:
If P, then Q.
Not P.
Therefore, not Q.
which may also be phrased as
P \rightarrow Q (P implies Q)
\therefore \neg P \rightarrow \neg Q (therefore, not-P implies not-Q)
Arguments of this form are invalid".
Not true.
The falsehood of the argument is only true when P and Q are not mutually exhaustive.
Easy eample: Truth and Falsehood.
If P(True) then Q(Not False).
Not P(True)
Therefore not Q(Not False).
How about a coin toss?
If heads then not tails.
Not heads
Therefore tails ( i.e. Not not tails ).  — Preceding unsigned comment added by 194.75.238.182 (talk) 14:17, 10 September 2015 (UTC)
thread_title:  These arguments are invalid? No, not all of them.