Talk:If and only if

Horrible article

This is my vote for the worst mathematics article in Wikipedia. People will come here for an explanation of a rather simple concept and the first sentence whacks them with "biconditional logical connective". Huh? Who is going to know what "biconditional logical connective" means but not already know what "if and only if" means? Answer: nobody. The article should explain what "if and only if" means in simple English first and the formal logic jargon should appear in some section later. Also, the section "Distinction from 'if' and 'only if'" is valiant but ultimately unsuccessful. As proved by the comments above, the meanings of "if" and of "only if" in common English are inconsistent and malleable, so trying to use ordinary sentences to explain the mathematical meanings of those words is doomed from the start. Incidentally, it is easy to explain "if and only if" without using the word "if": P if and only Q means that P and Q are either both true or both false. McKay (talk) 04:33, 15 April 2016 (UTC)

If you want it explained in "Simple English", you might be looking for the Simple English Wikipedia. Prinsgezinde (talk) 18:51, 30 January 2018 (UTC)

McKay does have a point. Article leads are supposed to be written in non-technical language so that someone with only a high school education can understand it (WP:LEAD#Provide an accessible overview); there's no restriction on how technical the content in the article body is though. Seppi333 (Insert 2¢) 19:32, 30 January 2018 (UTC)

McKay does have a point. Agreed; but it's worse than that. Hover your mouse over the word 'biconditional' in the very first sentence of the article- because you are (as you say) a person with only a high school education and you have not come across the word before - and you immediately enter an infinite loop. 86.148.153.228 (talk) 03:39, 14 September 2018 (UTC)

I don't see an infinite loop. Incidentally, regarding the initial sentences note that guidance can be found at MOS:MATHS, where we can read "The lead should as far as possible be accessible to a general reader, so specialized terminology and symbols should be avoided as much as possible." McKay (talk) 06:23, 14 September 2018 (UTC)

Copy and paste from Biconditional

< In logic and mathematics, the logical biconditional (sometimes known as the material biconditional) is the logical connective of two statements asserting " P {\displaystyle P} P if and only if Q {\displaystyle Q} Q", where P {\displaystyle P} P is an antecedent and Q {\displaystyle Q} Q is a consequent >

[My bold] - so what does 'if and only if' mean? 86.148.153.228 (talk) 21:47, 15 September 2018 (UTC)

I came here to understand what "IFF" means and now my brain is on fire. I barely never struggle to grasp the concept of any topic in any wikipedia page (i.e. do not require "simple language" usually). I would like to see the logic working on some plain english example. Like "if it is a meteorite, it falls from above. but if it falls from above, it is not necessarily a meteorite. it could also be bird droppings." - okay, I've now come back from the simple-language version and it has an example that I could understand. I think it should be in here as well. Fumquat (talk) 15:03, 23 February 2021 (UTC)

refers to (1), but there is no (1)

The sentence is:

 It does not, however, exclude the possibility that Madison 
 will refuse an apple if it is made available, in contrast 
 with (1) [...]

There is no (longer) "(1)". It seems clear to me that "(1)" should be replaced by something like "the above statement".

130.79.11.24 (talk) 08:56, 14 April 2022 (UTC)

Bad wikilinks in first sentence

According to MOS:SPECIFICLINK,one should not have two adjacent internal links like in the first sentence, which has the following:

> ..."if and only if" (shortened as "iff") is a biconditional logical connective between statements...

I'm not sure how I'd reformulate the sentence to separate the links, or which one would be more important to keep, but thought it was worth bringing up. Hansolo318 (talk) 17:17, 14 November 2023 (UTC)

• I think that guidance is broken daily. Drmies (talk) 17:19, 14 November 2023 (UTC)

The Madison apple example

Is hysterical i cant 2A02:6680:210D:F20C:E03E:6B5F:5B9A:3450 (talk) 17:32, 23 January 2024 (UTC)

Change "reverse" to "converse"

> The connective is biconditional (a statement of material equivalence), and can be likened to the standard material conditional ("only if", equal to "if ... then") combined with its reverse ("if"); hence the name.

I think "reverse" should be "converse" here. As far as I know only the terms "converse" and "inverse" are used in logic, because "reverse" is vague and can refer to either. 2001:630:E4:4220:1092:1F14:4423:828D (talk) 13:47, 23 April 2024 (UTC)