Of course there is also the Aristotelian argument of opposites that in which, the beautiful would have 2 opposites. The ugly and the not beautiful, although they're very similar they're not quite the same.
The not beautiful is not necessarily ugly by nature it just does not have any beauty within it. Even more confusingly something ugly can have beauty in it, but in it's totality it would still appear as ugly.
Personally I don't believe anything that has even the smallest bit of beauty should be considered beautiful, it must be beautiful in it's totality. But I do recognise it as a counter argument.