explain xkcd - User contributions [en]

704: Principle of Explosion

2014-10-31T16:12:55Z

108.162.230.89: Bracket sentence inserted. Yes, that mathematical point IS anal-retentive. But nevertheless true.

{{comic
| number = 704
| date = February 19, 2010
| title = Principle of Explosion
| image = principle_of_explosion.png
| titletext = You want me to pick up waffle cones? Oh, right, for the wine. One sec, let me just derive your son's credit card number and I'll be on my way.
}}

==Explanation==
[[Cueball]] explains the {{w|principle of explosion}}, a classical law of logic, that says that if you start out with propositions ({{w|axiom}}s) that contradict each other, it is possible to derive (prove) any statement you want in the language you are working in, true or false. (In math for example, if you assume that √2 is a rational number, you can 'prove' things that are obviously false, such as the fact that some numbers must be both even and odd. Consequently, you can draw the conclusion that √2 must be an irrational number (provided such a thing exists at all! - luckily, it does and obeys the same calculation rules as for rational numbers); this is how {{w|proof by contradiction}} works.)

Cueball's friend then proceeds to misinterpret (perhaps intentionally) that you can derive any ''fact'' about the physical world. His formula of {{w|propositional logic}} in the third panel reads "'''P''' and not '''P'''", where '''∧''' is the formal logic symbol for "and" and '''¬''' is the symbol for "not". '''P''' stands for a proposition. As "'''P''' and not '''P'''" is shorthand for "'''P''' is both true and false", this forms a contradiction from which the principle of explosion can begin. Humorously and to Cueball's bewilderment he then successfully manages to 'derive' his mom's phone number. His mom turns out to be [[Miss Lenhart]] (now a Mrs?), and to his vexation she asks his friend out.

Waffle cones are a variety of {{w|ice cream cone}}. The rest of the title text is just more of the main comic's derivation joke, since Cueball's "friend" is apparently a cheap bastard who can't spare five bucks to buy his own ice cream cones. (Unless he is smart enough to exploit the system of universe.)

==Transcript==
:[Cueball is talking to his friend.]
:Cueball: If you assume contradictory axioms, you can derive anything. It's called the principle of explosion.
:Friend: ''Anything?'' Lemme try.

:[Cueball's friend is writing on a piece of paper on a desk.]

:[Cueball's friend is holding up a piece of paper to Cueball, while holding a phone.]
:Friend: Hey, you're right! I started with '''P∧¬P''' and derived your mom's phone number!
:Cueball: That's not how that works.

:[Cueball is looking at the piece of paper, while his friend is talking to someone on a phone.]
:Friend: Mrs. Lenhart?
:Cueball: Wait, this ''is'' her number! How—
:Friend: Hi, I'm a friend of— Why, yes, I ''am'' free tonight!
:Cueball: ''Mom!''
:Friend: No, box wine sounds lovely!

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Miss Lenhart]]
[[Category:Math]]
[[Category:Logic]]
[[Category:Your Mom]]

Talk:753: Southern Half

2014-10-20T12:12:17Z

108.162.230.89:

OF COURSE! A Penis-Shaped Obelisk on Mars! And it's got to be big enough to been seen with an ordinary backyard telescope.--[[Special:Contributions/138.163.128.41|138.163.128.41]] 00:31, 20 March 2013 (UTC)
: And, yes, I imagine it ''would'' be hard. [[Special:Contributions/178.98.192.132|178.98.192.132]] 23:17, 4 May 2013 (UTC)
::"Hard" .... *facepalm*. [[Special:Contributions/173.245.54.168|173.245.54.168]] 14:37, 9 October 2014 (UTC)
Woah, woah, no cloned velociraptors in spaaace. Not on my watch. [[User:BruceJohnJennerLawso|BruceJohnJennerLawso]] ([[User talk:BruceJohnJennerLawso|talk]]) 05:25, 13 November 2013 (UTC)
:However, leave off Latin America and the rest seem to be pretty much in the hemisphere centered at the Persian Ocean.--[[Special:Contributions/108.162.215.9|108.162.215.9]] 07:14, 27 May 2014 (UTC)
I was under the impression that latin America did not include south America, just the part of north America south of the USA. [[Special:Contributions/108.162.219.7|108.162.219.7]] 02:20, 19 June 2014 (UTC)
Randall lacks to take in account the USA-centric view of the USA. If you define "south" as "more south than the USA", the speech sounds legit (especially if you subtract the Soviet Union from Asia - surely the enemy but not the "battlefield" Kennedy talked about). [[Special:Contributions/108.162.230.89|108.162.230.89]] 12:12, 20 October 2014 (UTC)

Talk:779: Anxiety

2014-10-16T11:15:48Z

108.162.230.89: Rule 34x. If you can think of a fetish, it exists. No exceptions.

I don't think it's Black Hat saying the title text but someone else in line. However, I'm not sure so I'm hesitant to edit it.[[Special:Contributions/173.245.54.64|173.245.54.64]] 15:54, 6 March 2014 (UTC)

I think the point is not about offending the backscatter operator, but more about men not wanting others to view their genitals in the flaccid state. Many men have self-esteem issues about genital size, and would be eager to take a pill that would make them appear larger before exposing themselves in that way. [[Special:Contributions/199.27.128.112|199.27.128.112]] 05:29, 2 May 2014 (UTC)

$20 a pill for a now-generic (Pfizer's patent expired in mid-2014) medication is a bit steep, yes?{{unsigned ip|108.162.250.223}}
:Not sure how that is in any way relevant, since the comic is from 2010. Are you suggesting that Randall on a regular basis should go back and adjust all his comics for inflation and other market developments? [[Special:Contributions/141.101.104.163|141.101.104.163]] 22:35, 5 October 2014 (UTC)

Backscattering fetish must be a subset of X-ray porn (which exists - no, really). [[Special:Contributions/108.162.230.89|108.162.230.89]] 11:15, 16 October 2014 (UTC)

Talk:979: Wisdom of the Ancients

2014-09-12T11:28:23Z

108.162.230.89: Via http://www.revk.uk/2011/11/denvercoder9-where-are-you.html

"There was uh, a thing called a segfault that made my computer like, all blurry and stuff." '''[[User:Davidy22|Davidy22]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 06:58, 2 February 2013 (UTC)

That was one reason why [http://stackoverflow.com/ StackOverflow] came to life: main authors fed up with (mis)using forums for query & answer site --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 23:03, 15 June 2013 (UTC)

Just two googling steps brought me here:
http://www.mirrorsoferis.com/forum/thread05232003a.html
Relevant for "Trivia"? Even the year fits! [[Special:Contributions/108.162.230.89|108.162.230.89]] 11:28, 12 September 2014 (UTC)

Talk:985: Percentage Points

2014-09-10T17:58:21Z

108.162.230.89:

Our study shows that only 5% of people know the difference between percentages and percentage points. This is 50% lower than in 2009. --[[User:DiEvAl|DiEvAl]] ([[User talk:DiEvAl|talk]]) 06:30, 16 August 2013 (UTC)

Actually, penis size based tax is a brilliant idea. You only have to tax proportional to size, and, now comes the utterly clever part, let the male citizen self-declare his penis size. Voila, tax flow will always be higher than planned. [[Special:Contributions/108.162.230.89|108.162.230.89]] 17:58, 10 September 2014 (UTC)