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The 2012 discussion about this matter did not reveal a single instance where material implication (rule of inference) is called “material conditional” or by some other name which redirects here, or may be mistyped in a way which gets a reader to this article. At least, I do not see there any concrete direction. The [1] edit was anything else than an attempt to circumvent the due process. Incnis Mrsi ( talk) 07:32, 8 May 2013 (UTC)
At present the lead section does not define "material conditional". Furthermore, it assumes some understanding of formal logic, but never actually positions "material conditional" within the study of logic. More detail, more basic explanation, and a definition of the concept would be appreciated. Cnilep ( talk) 01:22, 10 May 2013 (UTC)
“Reworking” undone. I will revert on sight any edits which injects a knowledge like
“ | in propositional calculus p→q is logically equivalent to … | ” |
(whatever a college student can derive from laws of Boolean logic), because a propositional calculus is not necessarily classical/Boolean. There is no such thing as the propositional calculus. Incnis Mrsi ( talk) 07:04, 29 May 2013 (UTC)
In the paragraph
"In classical logic p \rightarrow q is logically equivalent to \neg(p \and \neg q) and by De Morgan's Law to \neg p \or q"
the symbols for negation, logical and and logical or are neither explained nor linked to other Wikipedia articles. In this way, the article is not understandable to the layman.-- 84.150.172.61 ( talk) 09:06, 16 December 2013 (UTC)
I think that what it is said about monotonicity (under "Formal properties") is confusing. It is simple to see that material conditional is anti-monotonic in the first argument and monotonic in the second argument. Still, if we lift the reasoning from truth values to the inference process, then it is true that "if we know more, we cannot derive less" (in classical logic). Saying, as it is in the article, that if a→b then ∀c.(a∧c)→b doesn't mean that → is monotonic: the property is indeed true due to the anti-monotonicity of → in the first argument! (Adding "and c" to the premise can only decrease its truth value and thus increase the truth value of the whole implication, where "decrease" and "increase" refer to the total ordering of the boolean lattice ⊥ < ⊤). Is there anyone who thinks that these two levels should be clarified and kept distinct? Grace.malibran ( talk) 14:01, 9 January 2014 (UTC)
"But unlike as the English construction may, the conditional statement "p→q" does not specify a causal relationship...." I doubt that. Can anybody give an example of "If p, then q" which implies causality? I can think of many examples which might give rise to a suspicion of causality, but none in which the suspicion could be considered justifiable. "If you hit the ramp going less than 50 MPH, you're not going to make it." That suggests cause and effect, but I say it doesn't imply it; it just expresses a correlation. --Marshall "Unfree" Price 208.54.85.219 ( talk) 01:58, 26 May 2014 (UTC)
The current version (March 2016) reads: "However, unlike the English construction, the material conditional statement p -> q does not specify a causal relationship between p and q." This still seems specious, as the English construction does not necessarily specify a causal relationship between p and q. For example, in English I could say, "If I'm at a Fourth of July picnic, then there are going to be fireworks tonight." That does not specify any causal relationship between the two statements. (My presence at the picnic is not causing the fireworks, and the fireworks are not causing my presence at the picnic.) 74.71.76.34 ( talk) 14:06, 19 March 2016 (UTC)
I came to this article hoping to discover whether "material conditional" was the exact opposite of "counterfactual conditional". I suspect there might be a "factual conditional", in which case, I'll have to go on another errand, seeking the opposite of "material conditional". Oh, maybe it's "immaterial conditional". Who knows? --Marshall "Unfree" Price 172.56.26.37 ( talk) 02:09, 26 May 2014 (UTC)
I get it, a minimalistic style approach was taken making these diagrams, but why are they are not labeled?
http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Venn1011.svg/440px-Venn1011.svg.png — Preceding unsigned comment added by Scire9 ( talk • contribs) 20:43, 17 June 2014 (UTC)
The top of page Venn diagram of A --> B is wrong. One circle (A) should be completely inside the other (B). For example in the following image, Whale --> Mammal. http://faculty.ycp.edu/~dhovemey/fall2006/mat111/lecture/figures/whalesAreMammals.png. If it is a whale then it must be a mammal but if it is a mammal it may not be a whale. Hence whales are a subset of mammals. John Middlemas ( talk) 23:05, 31 July 2014 (UTC)
The sentence in the intro which begins
does not parse
It is trivial to prove the following using the rules of natural deduction:
(Truth table, line 1)
(Truth table, line 2)
(Truth table, lines 3-4)
(Often given as the definition of material implication -- not required in the above derivation of the truth table.)
It makes me wonder why so many folks believe that material implication is somehow different from the usage of implications in natural language. What's wrong with: If pigs could fly, then I'd be the King France? They should understand that anything that is true or false will follow from a falsehood.
Danchristensen ( talk) 03:23, 5 January 2018 (UTC)
The introduction is appallingly bad, it begins with reference to a currently non-existent diagram. Please would someone add an appropriate simple picture to show what this means ? And shouldn't the second paragraph should be the first ?
There is a lot of this article (and a lot of argument on this page) which is quite incomprehensible to the ordinary reader. Please would all WP editors concentrate on wording articles to inform and educate those who are not familiar with specialist subjects ? Darkman101 ( talk) 23:52, 6 July 2018 (UTC)
...is obviously a false statement since p and q are taken to be independent. Even worse, it is bolded in the lead. The operator, in words, should really read "if p or q is true and p is false then q is also true". Not so catchy, but more accurate and that's how the Teller source puts it. Also borne out by the article's own Venn diagram. Spinning Spark 09:05, 22 April 2020 (UTC)
There are several different forms of notation used in this page. I see the , , and → Which one should it be? Upascal ( talk) 18:49, 5 March 2022 (UTC)
<math>
versions for the sake of forward-compatibility, since future expansions might introduce content that can't really be typset without math mode. But beyond that I have no preference. Thanks for putting in the labour by the way!
Botterweg14
(talk) 19:42, 5 March 2022 (UTC)Should we note the fact that a → b is equivalent to "a less or equal then b"? In fact, it's a logical comparation. 178.120.21.187 ( talk) 20:16, 29 April 2024 (UTC)
This is the
talk page for discussing improvements to the
Material conditional article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find sources: Google ( books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL |
Archives: 1 |
This
level-5 vital article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||
|
The 2012 discussion about this matter did not reveal a single instance where material implication (rule of inference) is called “material conditional” or by some other name which redirects here, or may be mistyped in a way which gets a reader to this article. At least, I do not see there any concrete direction. The [1] edit was anything else than an attempt to circumvent the due process. Incnis Mrsi ( talk) 07:32, 8 May 2013 (UTC)
At present the lead section does not define "material conditional". Furthermore, it assumes some understanding of formal logic, but never actually positions "material conditional" within the study of logic. More detail, more basic explanation, and a definition of the concept would be appreciated. Cnilep ( talk) 01:22, 10 May 2013 (UTC)
“Reworking” undone. I will revert on sight any edits which injects a knowledge like
“ | in propositional calculus p→q is logically equivalent to … | ” |
(whatever a college student can derive from laws of Boolean logic), because a propositional calculus is not necessarily classical/Boolean. There is no such thing as the propositional calculus. Incnis Mrsi ( talk) 07:04, 29 May 2013 (UTC)
In the paragraph
"In classical logic p \rightarrow q is logically equivalent to \neg(p \and \neg q) and by De Morgan's Law to \neg p \or q"
the symbols for negation, logical and and logical or are neither explained nor linked to other Wikipedia articles. In this way, the article is not understandable to the layman.-- 84.150.172.61 ( talk) 09:06, 16 December 2013 (UTC)
I think that what it is said about monotonicity (under "Formal properties") is confusing. It is simple to see that material conditional is anti-monotonic in the first argument and monotonic in the second argument. Still, if we lift the reasoning from truth values to the inference process, then it is true that "if we know more, we cannot derive less" (in classical logic). Saying, as it is in the article, that if a→b then ∀c.(a∧c)→b doesn't mean that → is monotonic: the property is indeed true due to the anti-monotonicity of → in the first argument! (Adding "and c" to the premise can only decrease its truth value and thus increase the truth value of the whole implication, where "decrease" and "increase" refer to the total ordering of the boolean lattice ⊥ < ⊤). Is there anyone who thinks that these two levels should be clarified and kept distinct? Grace.malibran ( talk) 14:01, 9 January 2014 (UTC)
"But unlike as the English construction may, the conditional statement "p→q" does not specify a causal relationship...." I doubt that. Can anybody give an example of "If p, then q" which implies causality? I can think of many examples which might give rise to a suspicion of causality, but none in which the suspicion could be considered justifiable. "If you hit the ramp going less than 50 MPH, you're not going to make it." That suggests cause and effect, but I say it doesn't imply it; it just expresses a correlation. --Marshall "Unfree" Price 208.54.85.219 ( talk) 01:58, 26 May 2014 (UTC)
The current version (March 2016) reads: "However, unlike the English construction, the material conditional statement p -> q does not specify a causal relationship between p and q." This still seems specious, as the English construction does not necessarily specify a causal relationship between p and q. For example, in English I could say, "If I'm at a Fourth of July picnic, then there are going to be fireworks tonight." That does not specify any causal relationship between the two statements. (My presence at the picnic is not causing the fireworks, and the fireworks are not causing my presence at the picnic.) 74.71.76.34 ( talk) 14:06, 19 March 2016 (UTC)
I came to this article hoping to discover whether "material conditional" was the exact opposite of "counterfactual conditional". I suspect there might be a "factual conditional", in which case, I'll have to go on another errand, seeking the opposite of "material conditional". Oh, maybe it's "immaterial conditional". Who knows? --Marshall "Unfree" Price 172.56.26.37 ( talk) 02:09, 26 May 2014 (UTC)
I get it, a minimalistic style approach was taken making these diagrams, but why are they are not labeled?
http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Venn1011.svg/440px-Venn1011.svg.png — Preceding unsigned comment added by Scire9 ( talk • contribs) 20:43, 17 June 2014 (UTC)
The top of page Venn diagram of A --> B is wrong. One circle (A) should be completely inside the other (B). For example in the following image, Whale --> Mammal. http://faculty.ycp.edu/~dhovemey/fall2006/mat111/lecture/figures/whalesAreMammals.png. If it is a whale then it must be a mammal but if it is a mammal it may not be a whale. Hence whales are a subset of mammals. John Middlemas ( talk) 23:05, 31 July 2014 (UTC)
The sentence in the intro which begins
does not parse
It is trivial to prove the following using the rules of natural deduction:
(Truth table, line 1)
(Truth table, line 2)
(Truth table, lines 3-4)
(Often given as the definition of material implication -- not required in the above derivation of the truth table.)
It makes me wonder why so many folks believe that material implication is somehow different from the usage of implications in natural language. What's wrong with: If pigs could fly, then I'd be the King France? They should understand that anything that is true or false will follow from a falsehood.
Danchristensen ( talk) 03:23, 5 January 2018 (UTC)
The introduction is appallingly bad, it begins with reference to a currently non-existent diagram. Please would someone add an appropriate simple picture to show what this means ? And shouldn't the second paragraph should be the first ?
There is a lot of this article (and a lot of argument on this page) which is quite incomprehensible to the ordinary reader. Please would all WP editors concentrate on wording articles to inform and educate those who are not familiar with specialist subjects ? Darkman101 ( talk) 23:52, 6 July 2018 (UTC)
...is obviously a false statement since p and q are taken to be independent. Even worse, it is bolded in the lead. The operator, in words, should really read "if p or q is true and p is false then q is also true". Not so catchy, but more accurate and that's how the Teller source puts it. Also borne out by the article's own Venn diagram. Spinning Spark 09:05, 22 April 2020 (UTC)
There are several different forms of notation used in this page. I see the , , and → Which one should it be? Upascal ( talk) 18:49, 5 March 2022 (UTC)
<math>
versions for the sake of forward-compatibility, since future expansions might introduce content that can't really be typset without math mode. But beyond that I have no preference. Thanks for putting in the labour by the way!
Botterweg14
(talk) 19:42, 5 March 2022 (UTC)Should we note the fact that a → b is equivalent to "a less or equal then b"? In fact, it's a logical comparation. 178.120.21.187 ( talk) 20:16, 29 April 2024 (UTC)