Arguing about the definition of a word is a huge red flag that a discussion is going nowhere. Sadly a lot of philosophy seems to be basically arguing about words.<p>&gt;Do black holes exist? Electrons? Magnetic fields?<p>Yes. I mean we might not know what they are exactly or how they work, but they are clearly real phenomena that we can observe. In the same sense, &quot;twoness&quot; is a real property that a set of objects can have.