|Glass completely full. (Image ethically sourced from here.)|
Some actually regard this a a serious philosophical question, but to me it represents a logical fallacy that I can't exactly name. It is something like the fallacy of the missing middle, but not exactly the same. There are other ways to look at the problem.
To one engineer it might be said that the glass is twice as big as it needs to be.
To another engineer, the glass is completely full but only half-filled with liquid. The other half is filled with air.
As for me - I always thought from a pragmatic point of view that the glass is half-full if you are filling it and half-empty when you are drinking from it.
Another view that someone passed to me recently was that while we've spent all that time arguing about the glass, someone swiped it and drank the contents. Now the answer is a bit easier . . . and its your round!