## Using Mathematics as an argument

### 2011/02/10

I just came out of a meeting where the following phrase was spoken (and the meeting’s context does not really matter):

*– Mathematics has spoken. You can never ever have everything as a variable. You have to have constants.*

This was used as a *math-therefore-I-am-right-full-stop* argument. Never, ever use Mathematics, Science or any other bus-stop argument in a room filled with 60+ people with Mathematics, Engineering and Computer Science degrees and expect to be taken seriously. Interpret the fact that you were not countered as politeness instead.

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2011/02/12 at 4:05

please explain.

2011/02/12 at 22:05

I really do not think that there is something to explain: Where in Mathematics is it written that you have to have constants and not only variables? And what is this sentence supposed to mean? Can I not have a f(x,y) = x*y ?

The closest thing that comes to mind, is the scientific argument that states to change only one variable at a time keeping all the others constant, so that you can study the impact of your changes. But he did not say that. And it took me over an hour to reach to this hypotheis just to give him the benefit of the doubt. And he insisted that because mathematics has spoken (when? where?) he is correct. Someone who is correct uses correct, unambiguous wording.

Using a random appeal to Math (or even Physics) to claim validity of your argument requires an untrained audience.

2011/02/18 at 5:42

Actually he is trivially correct:

f(x,y) = x*y = 1*x*y

This applies to all cases where multiplicative identity (or even additive identity, but that’s even more trivial) is defined.

But I have a feeling that this is not exactly what that guy meant…

2011/02/19 at 11:55

What you supposed is right but he didn’t say that. He said ” You can never ever have everything as a variable”. I don’t know the context this was said but mathematically it makes no sense, I could almost say that it is impossible.

I have an explanation based in common sense. I feel the guy confuses the expression of a function where all variables are replaced by a value (wrongly perceived as constant) with an immediate result (also wrongly perceived as constant) with a constant function (or a function from where variables are magically removed to somewhere :))

what i mean is

f(x,y) = 4x^2 + 3x + 7

What he would like to have is

x=2

y=3

arithmetic…

f(x,y)= 32

you should explain him that even when variables are valued and even when these values stay for a very long time or they are the only values this problem can take, mathematically they are not constants they are still valued variables

2011/02/19 at 22:29

@thanos, @foteioula:

Thank you both for your comments. However, although highly irritated I chose to do what the other 60 people in the room did: ignore the person, his opinion or anything else he had to say for the matter at hand.

2011/02/21 at 23:29

In situations like that, the winning move is not to play.

2011/02/22 at 20:10

ah yes… of course!if you did so that’s great! I thought that you expressed there what you said at the post highly irritated :)

2011/02/21 at 15:11

Let’s assume the guy had said:

“Mathematics has spoken. 1+1 = 2”

Does your statement stand?

“This was used as a math-therefore-I-am-right-full-stop argument. Never, ever use Mathematics, Science or any other bus-stop argument in a room filled with 60+ people with Mathematics, Engineering and Computer Science degrees and expect to be taken seriously”

2011/02/21 at 15:22

Correct! He could have used Pythagoras’s Theorem or even the color of the wall as an argument too! Arguing that what you say is true because something irrelevant to the matter is also true is a typical, yet highly unsuccessful, proof strategy. Using Mathematics in such a strategy makes things even more hilarious / irritating (your choice).

2011/02/21 at 17:46

> “because something irrelevant”

Hmmm, I think that’s what it all boils down to. 1+1=2 is, without doubt, correct. But how do relate that fact to your argument, with the same certainty (as in 1+1=2)?

point taken