compartmentalizing
The act of splitting an idea or concept up into (more or less arbitrary) parts, and trying to enforce thought processes which are inhibiting attempts to allow these parts to mix together again.
The reason for this attempt of thought control is often to make it more easy to single out certain individuals, or to inhibit certain ideas.
one example is the idea of gender, splitting gender into exclusive male and female treats, ignoring the fact that sometimes gender is not that easilly determined.