When someone posts “2+2=4” to make some point, inevitably some wiseass comes back with, “well, 2+2=5 for large values of 2.” I’ve assumed that this means that, for example, 2.49+2.49=4.98, which, if rounded, would be written as 2+2=5.
Am I correct?
Sua
I think it’s a joke based on approximations.
Thanks.
Interesting - the way it was explained to me (I forget where) was subtly different to that - it wasn’t about rounding, so much as about geeky tunnel-vision - to be so focused on the theory of the thing as to overlook the obvious hard, real-world fact that 2 is not a variable.
How in the world would it demonstrate that? The phrase “for very large values of 2” would clearly indicate that “2” IS variable. The meaning of “2” changes; while we tend to think of it as indicative of the integer meaning 1 + 1, it can mean an estimation of an infinite number of real numbers, all surrounding the integer on the number line.
I remember that mailbag column. But I also remember Stalin’s? Khrushchev’s? (okay, not so well) pronouncement about how good the five year plans were.
That, and Winston Smith.
In most real world applications you come up with the numbers you want to add by some measurement process which will have error. So you know you want to add two and two but how precise you know two is up for debate.
Exactly my point, and quite the opposite of what Mangetout was saying with the phrase “real-world fact that 2 is not a variable.” 
Folks, it’s a joke. It always has been a joke. It’s the type of joke that makes the joke teller the butt because it’s blatantly impossible for the number two to be anything other than the number two.
I used the same joke back in high school physics. There was one equation that included Planck’s Constant in it. The teacher asked how you could get a larger result and I said “Increase Planck’s Constant.” That was a joke, too. (The same joke, as a matter of fact.)
Now, as a metajoke, people are pointing out how by rounding you can get to five, but that came later and is not necessary in order to understand the original joke, which is “large values of 2” is a nonsense phrase.
Cite for your assertion, please?
DSYoungEsq, you’re whooshing us, right?
No, I am not whooshing anyone.
First, you made an assertion that, as I’ve explained, doesn’t make sense. Then someone made an assertion that the whole thing is just a joke with no real meaning, like saying something contradictory just to get a laugh, rather than pointing out a specific thought process about numbers and rounding. I’ve asked that person for a citation that this is the case, that the “metajoke” as that person put it came AFTER the joke itself.
The phrase is a carefully constructed attempt to show an anomoly: the variance in thought between what most people learn in the way of the meaning of cardinal numbers (integers) and the potential actual meaning of cardinal numbers (real numbers that have been rounded to the nearest integer). It uses a patently nonsensical mathematical calculation to demonstrate this anomoly. It’s almost inconceivable that the phrase was developed as nothing more than a nonsensical joke, and then someone else came along later and said, “You know, that actually makes sense if you interpret it this way…” :dubious:
Crikey. I give up. I know what I mean, but I don’t think I can explain it to you.
I’d agree with DSYoungEsq. The joke is in origin pretty certainly a rather sophisticated geek joke, the kind that originates on university campuses. It makes the point that the meaning of “two” is not constant if you are dealing with continuous versus non-continuous variables. The exact value of the quantity given as “two” can differ depending on the precision of measurement. RealityChuck’s explanation of the origin doesn’t make much sense.
I’ll second Mangetout; I vaguely thought I read somewhere once upon a time some example of false logic where by using highly specious mathematical terms and operations, you ended up with 2+2=5.
Here’s the Wiki article on “2+2=5” and its popularization in Orwell’s 1984.
Regarding “very large values of 2,” the article agrees that this is a geek joke about estimation errors.
Wiki may not be definitive, but it certainly supports the idea that this is the common explanation for the joke.
Another frequent formulation of the concept is “2 does not equal 3, even for very large values of 2.”
Something known as a “Sense of Humor.” See Colrabi’s post above. In addition, the slogan was around for years (I saw it in the 80s) before anyone ever attempted to justify it.
Can you cite anyone who ever made this assertion seriously?
This phrase does go hand-in-hand with the original concept, as explained correctly by RealityChuck . The number 2 is a discrete natural number that doesn’t have “very large values”. Therefore it can never equal three. If this statement was also a joke about rounding and estimating, then it would read, “2 equals 3, for very large values of 2”.
I propose we change the rounding and estimation joke to “2 + 2 = 6 for very large values of 2”, and keep the “2 is a discrete natural number” joke as “2 + 2 = 5 for very large values of 2”. Then everyone’s happy.
Will one of you change the Wikipedia entry or shall I?