2+2=5 wall of shame

submitted by xoenix from midi.moe

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[–]binaryblob 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (3 children)

2+2=5 could be true in some system of logic. It's just that to understand that sentence, you need a university education with good grades.

None of the people talking there will understand.

Most people can't prove 2 + 2 = 4 in its usual interpretation, which is fucking pathetic, because even computers can do that since the 1960s.

[–]LtGreenCo 5 insightful - 1 fun5 insightful - 0 fun6 insightful - 1 fun -  (1 child)

2+2=5 could be true in some system of logic

It would not be a practical system of logic, not for us anyway. Sure we can get creative and come up with fictional systems and wax philosophical about it all day but it doesn't change anything.

Any actual system where, conceptually, 2+2 really equals 5, if it even exists, would be so insane and unfathomable to our tiny brains that we'd have to ascend to an entirely new plane of existence to even begin to grasp it.

[–]binaryblob 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (0 children)

If you don't know what you are talking about, why do you speak?

[–]weavilsatemyface 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (0 children)

2+2=5 could be true in some system of logic.

The issue isn't with logic but with arithmetic.

We could invent a system of arithmetic where 2 + 2 = 5 is true. The trivial way to do so would be:

  • Redefine the symbol "2" to mean something else. Or "5", or "+", or "=".

But that's not changing the semantics of the statement, only the symbols used. It's not an honest change, it's just a trick:

"Aha, but if the symbol = means not equal to, then it's absolutely true and correct that 2 + 2 = 5. Gotcha!"

And that argument is about as honest and sincere as it would be if I called you "a stupid poop-head" and then insisted that in my sentence "stupid" actually means very smart and "poop-head" actually means "handsome".

There are other such tricks that can be played, like defining two as the gaps between three vertical lines "|||" and the "+" sign as concatenation:

2 + 2
= ||| + |||
= ||||||

which has five gaps and therefore 2+2 = 5. But of course this too is just a trick of changing the meaning of words and symbols.

Most people can't prove 2 + 2 = 4 in its usual interpretation, which is fucking pathetic, because even computers can do that since the 1960s.

Dude. Dude. Of course they can: hold up two fingers, hold up another two fingers, and count them. Four fingers.

That's a perfectly satisfactory proof. And before you start going on about Bertie Russell's Principia Mathematica, I'm just going to say three words: Gödel's incompleteness theorems.

The only semi- standard way to get "2+2=5" is to define the group Z_2 as the set {0, 1} under addition modulo two, in which case 1+1 = 0 (mod 2). Modulo arithmetic (or "clock arithmetic") is standard. Now form a group isomorphic to this Z_2 but rename the element 0 to 5 and 1 to 2. So now we have 2 + 2 = 5.

Except this is still just a linguistic trick, where we redefine regular addition as clock addition modulo 2, redefine the symbol 5 to mean zero and 2 to mean one, and the symbol = to mean equivalent to under modulo addition.

There are tons of other "tricks" (some funnier than others) you can use to prove this, like the guy who proved that 2 + 2 = 5 by taking a piece of string with two knots in it, and a second piece of string with two knots in it, and tied them together. Ta-da! A piece of string with five knots in it.