Duality

Bias.

 You're showing your mortality, dear Duality.

 See, Infinity is a concept. Proper context of aforesaid question denotes a specified Infinity and thusly the simplest answer of namely numbers. Alas, but numbers themselves are fully conceptualized. One can not hold up a singular entity as Five and point this being the five. Only a representation of things being grouped into what the mortal mind denotes as being assigned to the amount corresponding to that number. Therefore, Infinity is a collection concept of collected concepts. Self-perpetuating and only holding meaning within the mind that choses to direct effort into conceiving of it.

 Effectively, self-proving it wrong by means of self-perpetuation.

 All human concepts are effectively wrong by their basest state.

 One would not bottle up the concept of the color Grey and sell it to others so they could experience true Greyness. (Note to self, new business idea.) To whit, since you brought it up, you are already Wrong.

Wrongness, of course also being a Concept, but I called you it and being the being that formed that utterance's meaning henceforth win and can feel superior in this moment.

@Stone Cold Steve Tuna

Oh yes, I had an Orm for a teacher once! She was great! Apart from the many times we had to find a substitute to replace her when she frequently disapparated from the Space-Time Continuum! Oh, those whacky Orms!

@Widdershins

You show far more bias than me, good sir. You're holding to a radical realist philosophical position, summed up by the 'if you can't hold one up and point to it it doesn't exist' perspective. This is actually quite a minority view among scientists, mathematicians, philosophers, etc., due to its extremely narrow-minded (read: heavily biased) insistence on 'holding up and pointing to' (and at any rate, the fact that beings like us can't hold up and point to concepts has no bearing on whether there exist beings that can do so in some parallel form of existence).

Everything you know and love is a concept, insofar as all we know about the universe surrounding us is via sensory inputs translated into coherent experience by our minds. Just because we can't see, hear, or smell it doesn't mean it doesn't exist and regardless of whether something exists in concrete form you can't say whatever you like about it anyway. Things can be true or false if said about concepts just as much as they can be true or false if said about assemblages of sensory inputs - and what promotes the objects of nasal stimulation above the objects of mental stimulation anyway? Why is it that what I smell you call more real than what I think about, given that thought forms the core of my existence? Why are you, in short, so biased towards self-evidently irrational sensations as opposed to rational thoughts? What evidence do you have that what we call the physical universe exists when nobody's sensing it any more than numbers dissolve into nonexistence when nobody's thinking about them?

Furthermore, 'goodness' is a concept. However, if you said 'eating babies is a good thing' you'd either be a liar or a madman depending on whether you knew that such a statement is false. 'Infinity' is a concept - so are finite numbers, and you can't say whatever you like about them either. 1 + 1 makes 2 by the axioms of mathematics, and if you said otherwise you'd be just as rejected by people who know who they're talking about as if you said eating babies is the pinnacle of morality.  The same axioms of mathematics that say 1 + 1 = 2 include infinity as a direct consequence, even the most basic among them. Peano's axioms are some of the simplest around (only dealing with whole numbers), and even they include the Axiom of Infinity stating that there exists at least one infinite set - otherwise you'd have to add a whole lot of convoluted numerical detours to define the set of whole numbers properly.

I can say things about concepts that are true and things about concepts that are false. Grey is a colour between black and white on the monotone spectrum. Grey is not a shade between red and mauve on the RGB colour gamut. The only difference between the infinities and finite numbers is that you can count to finite numbers. Concepts do not have to be demonstrably formed in physical reality (e.g., counted to) to be considered 'valid'. Concepts by definition are independent of demonstrable forms in physical reality. I can therefore say true and false things about infinity. True: there is not just one infinity, there are more than infinite of them. False: your mom's weight is less than infinity.

Reality is in the eye of the beholder.

 By mortals' merit, it is equated that the more defined characteristics of something there is the more it is both described as being physical and therefore "Real." We smell an orange, taste an orange, rhyme things with orange, describe it as having the color of orange. Because of these relations to other things in our perceived reality that are, in turn, also defined by their relations to other things, we view it as more concrete in its physicality. 

 The line is blurred further going into concepts. 1+1=2 and among other things, we can have numbers interact in as equally perceived realistic terms. But numbers relate less so to direct sensual interaction; we cannot eat the number two. This does make the concept of numbers less real than an orange, but more real than the concept of Justice or the difference between Right & Wrong. I would intone that the less capacity you have to interact with a concept point defined as singular, makes it less "real" on a personal, case-by-case basis. Certainly I am not arguing anything so simple as "if you can't eat it, it ain't real" despite my thoughts on which numbers might prove to be more delicious than others.

 We claim an orange has the quality of being colored orange because of the mortal assumption that we know what others quantify as the color and having had equitable sensory input the same as our own. This can be extended to mathematical equation as well. While provable in a great many ways, the mathematical systems may vary wildly in other worlds, other dimensions. In my being wrong as to how numbers equal out to, if steadfast in my view of how I sense those numbers coming together, am I any different in my numerical sensory systems then your own standpoint on how that has been proven by your peers? Does not my wrongness prove as equally real as your rightness? For example:

3 X 3 = Bleventy-Floog!

  Do notice my not arguing the weight of mah momma.