Talk:Therefore sign

Picture wanted
Perhaps a picture of the sign? For those who don't have a font that includes it Carewolf 16:26, 25 April 2007 (UTC)

Yes PLEASE! =)Twitterpated. (talk) 20:36, 7 January 2008 (UTC)

That would be great. For the majority of us, it shows up as a box. —Preceding unsigned comment added by 65.92.122.92 (talk) 01:08, 19 September 2008 (UTC)

Q.E.D.
In many mathmatics textbooks, this means "Q.E.D." in proofs. Perhaps we should add that? Would a single textbook be enough for citation? —Preceding unsigned comment added by Budster650 (talk • contribs) 01:20, 24 November 2007 (UTC)

Yes I agree. Also as this 'therefore' sign as it's own entry in Wikipedia, shouldn't it be added to the list of mathematical symbols which also has it's own entry? And also to the list of mathematical logical symbols which has it's own entry? 92.234.36.26 (talk) 20:44, 7 March 2008 (UTC)


 * The use of the therefore symbol to mean Q.E.D. is nonstandard. I've never seen it.  It's a personal quirk, like using a heart symbol (some people do).  Zaslav (talk) 01:36, 22 August 2020 (UTC)

Because sign for premise?
Would it be proper to indicate a premise with the because sign? For example:

∵ All men are mortals. ∵ Socrates is a man. ∴ Socrates is a mortal. —Preceding unsigned comment added by 75.45.203.208 (talk) 05:54, 10 April 2009 (UTC)


 * No. It is rather like gilding the lily, but worse, because the two hypotheses must be asserted before a logical inference is made.  The way to use "because" is to replace the third line by
 * ∵ All men are mortals and ∵ Socrates is a man, ∴ Socrates is a mortal.
 * But that is simply to perform a "What the Tortoise Said to Achilles" trick of regression.  Zaslav (talk) 01:41, 22 August 2020 (UTC)

Why 3 dots in triangle form?
The article doesn't actually explain why the "therefore" sign is 3 dots in a triangle shape. Can anyone help? —Preceding unsigned comment added by 203.193.207.246 (talk • contribs) 05:45, 21 September 2009 (UTC)


 * Can you think of a better shape to arrange 3 dots in? —Wiki Wikardo 04:36, 3 November 2013 (UTC)

Has word processing made the therefore sign a threatened species?
I'm in my sixties. I studied Mathematics at university in the 1960s and made a career change to become a high school teacher of mathematics five years ago. Having been brainwashed by my high school teachers to use the therefore sign on every line of a logical mathematical solution, I was distressed to see the sign missing from modern textbooks, and to encounter students at senior levels who had never heard of it. My theory to explain this is that while my textbooks way back then were typeset by professionals with access to extensive sets of characters, modern textbook writers use only those characters visible on computer keyboards. (More knowledgeable and fussy writers could use ASCII key combinations, but most won't even know how.) There is no therefore sign on my keyboard. I predict it becoming extinct within 20 years. HiLo48 (talk) 03:05, 22 November 2009 (UTC)

Hence you see the decay and dumbing down of the modern educational system. R.I.P --Krakaet (talk) 20:47, 7 May 2013 (UTC)
 * Hardly. Many abbreviations and shorthand symbols were used to conserve space and provide expediency, since paper was expensive and notes were often hand-written. Nowadays, with modern technology, abbreviations and the like are largely historical artifacts. –Nøkkenbuer (talk • contribs) 18:33, 26 March 2015 (UTC)

I don't think so. I learned it in high school only a decade ago. Until learning mathematical concepts through practicing by hand dies out, symbols like this will always be welcome by those whose hands hurt or need to save time on tests. I'm sure it varies from teacher to teacher, textbook to textbook. Regarding computers, it only saves a little space on the page and you need to move your hands from the home row and type a special sequence, so it's not a useful shorthand for technology. But if I'm doing math on the computer, I'm doing programming, so I have to follow the syntax of that language. Wumborg (talk) 17:40, 25 April 2014 (UTC)

This article references it's own talk page
Does this count as a proper reference? 94.7.70.153 (talk) 12:00, 1 May 2010 (UTC)
 * Of course not! WTF? There's not even a statement asserting that the described use of the symbol is proper on the talk page, but a question if it is! LOL! I've removed the reference; thank you for pointing it out. Florian Blaschke (talk) 18:22, 20 May 2010 (UTC)

How does Windows handle this character?
There are no mention of alt-codes used in the Windows operating systems. Alt+8756 produces "4" in most applications (excepting Word). This character does not appear in Arial or Times New Roman, yet most apps will display the pasted character properly without any font substitution (such as Firefox). The character can be copied and pasted, but not created in Windows. Further topic, how does Windows perform this slight-of-hand? Many people online are looking for an answer to this; perhaps Wiki editors can find the answer. I've hit the limit of my abilities. —Preceding unsigned comment added by 205.156.36.16 (talk) 15:39, 9 June 2010 (UTC)


 * Ten years too late, but just in case anyone still cares... The traditional Windows alt codes are undefined for numbers above decimal 255, hex FF, so there is no alt code for this character except the Unicode input method. Modern versions of Windows all use Unicode as standard so it is not a significant issue that needs to be mentioned in this article. --John Maynard Friedman (talk) 11:43, 22 August 2020 (UTC)

Does any notable author (of the 20th or 21 century) actually use this as "therefore"?
A search in google books turned up nothing, ("Therefore sign" three dots) but searching for the actual symbol is not possible with google's OCR... Tijfo098 (talk) 18:46, 27 November 2012 (UTC)


 * I found reference in www.math.washington.edu/~lee/Writing/writing-proofs.pdf‎ although I am not familiar with the authority of this person in respect to the field. It should be noted that the author also suggests writing it in English as "therefore" when used in a sentence. Furthermore, one could try to search "mathematical proof therefore" in Google Images. First I tried some simple cross-references on historical documents but, for obvious reasons of complications scanning ancient math proofs on papyrus etc., did not yield much result. Searching Google images, I found reference of the sign on about 3 occurrences (visual confirmation on thumbnails alone). This is probably not by any notable author though and I'm not a mathematical historian with sufficient access to this kind of sources.
 * Solobit (talk) 20:23, 16 June 2013 (UTC)


 * See my thoughts in the section above titled "Has word processing made the therefore sign a threatened species?" HiLo48 (talk) 22:29, 16 June 2013 (UTC)

Mi vida loca
Seriously, if we’re including Japanese maps and freemasons, should we not include the mi vida loca tattoo? —Wiki Wikardo 04:36, 3 November 2013 (UTC)

Second example of use is not a syllogism
The second example under Examples of use,


 * x + 1 = 6
 * x = 6 - 1
 * ∴ x = 5,

is not a syllogism, as the conclusion is not based on two propositions, but only on one, since the second line is a consequence of the first proposition and hence not a new proposition. Maybe we should change this example to something like


 * x + y = 6
 * y = 1
 * ∴ x = 5,

which would make it a syllogism? —Kri (talk) 18:28, 13 November 2015 (UTC)

External links modified
Hello fellow Wikipedians,

I have just added archive links to 1 one external link on Therefore sign. Please take a moment to review my edit. If necessary, add after the link to keep me from modifying it. Alternatively, you can add to keep me off the page altogether. I made the following changes:
 * Added archive https://web.archive.org/20081014090303/http://www.scenta.co.uk:80/tcaep/maths/symbol/Mathematical%20Symbols/index.htm to http://www.scenta.co.uk/tcaep/maths/symbol/Mathematical%20Symbols/index.htm

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Cheers.—cyberbot II  Talk to my owner :Online 05:36, 20 January 2016 (UTC)

In this century?
The final sentence of the History section tells me "In this century, the three-dot notation for therefore became very rare in continental Europe, but it remains popular in the British Isles." Which century?

Given that the previous sentence finished with "...in the nineteenth century", is that the century being referred to? Or is it the 21st? Or something else?

The source linked to didn't help me understand at all. HiLo48 (talk) 03:46, 6 July 2018 (UTC)

Freemasonry?
The Freemasonry section is poorly written. The claimed connection to "therefore" does not make sense. Zaslav (talk) 01:43, 22 August 2020 (UTC)


 * Done. It was mostly pointless waffle. --John Maynard Friedman (talk) 11:32, 22 August 2020 (UTC)