Categorizing things...

Comments on whether you prefer to categorize in one of the following ways:-

• - Single - a very existential approach - to be or not to be...
• - Dual - It's either this thing or that [only two choices]
• - Triple - It's this or that or the other [no one likes to be the other]

I found that categorizing things in hierarchical groups of 3 enables us to make sense of prioritization with a minimum number of levels. For example the hierarchy shown above Things -> {Numbers{Even, Prime,Other}, Colors{Purple,Cyan,Blue}, Shapes{Circles, Rectangles,_}}.