If you say half empty it means you have a pessimistic look on life, if you say half full your an optimist.
Well I say bollocks to that!
The concept of the question is fundementally flawed as full and empty can both be positive and negative interpretations of an event. You can have a negative vibe on half full: “my firkin of Mild is still half fall and it’s on its expiration date”
And a positive view of half empty: “flooded cellar is now half empty”.
But surely the flaw in the pint of beer analogy is in which direction is the liquid supposed to be going? If you are drinking it, it is s positive sign as you are enjoying it, hence the beer going down. And if it is being filled then it also a positive. Likewise if it is being poured and there is only enough for half a glass… it is a bad thing.
So never move over metaphysical cats, a pint glass at 50% capacity is an actual example of an item in two metaphysical existences.