Look, let's do this mathematically people.

Let **G** be the set of all possible levels of liquid in a glass, and let **g** be an element of **G** such that **g** is the maximum level of liquid in the glass. Now, let **l _{e}** be the level of water in a glass half-empty, and

**l**be the level of water in a glass half full. Then,

_{f}**l _{f}** = (1/2)*

**g**, and

**l**=

_{e}**g**- (1/2)*

**g**

But, **l _{e}** =

**g**-(1/2)*

**g**

= (2/2)*

**g**- (1/2)*

**g**

= (1/2)*

**g**

=

**l**

_{f}Therefore, **l _{e}** =

**l**

_{f}So, any glass that is half empty is also half full. Now can we please put this question to rest?