well, due to the surface tension of water you can fill the glass to significantly past its brim. therefore, this "half" is less than half if the half is measured by height (i.e. there is less than half the capacity of liquid in the glass), so therefore it is neither half empty nor half full since it is less than half full and more than half empty.
if the half is measured by volume (i.e. is half of the total capacity of the glass), then it is more than halfway up the side of the glass and is therefore more than half full or less than half empty, so is neither half full or half empty.
if the half is the middle of those two then it is not half by either measure and therefore this also fails.
therefore there is no such thing as the glass being half full or half empty. we can only assume that the glass has liquid, which cannot be refuted if the glass is attempting to be half full (because it must have liquid if it has volume.). the only other alternative is that the glass does not exist which would allow the volume of the water or other drink to also be 0. but if this were the case then the glass too doesn't exist and we've wasted our time talking about a nonexistent glass.
but this is all hypothetical so the glass doesn't actually exist anyway and therefore you've wasted your time reading through this pile of rubbish, just like i have wasted my time writing it.