Dialectician

Kung-sun Lung was the person who represented the main thoughts of this school, but only a part of his writing has been preserved, others were lost. Dialecticians discussed names, existence, relativity, space, and time. This was the only school to discuss logical and epistemological problems. Dialectician (Ming Chia in Chinese) equals the logic and epistemology today.

One of the main goal of this school was to attain precision of concepts. The most famous theory of Dialectician is the Discourse on a White Horse. White horse is a horse, so if you want a white horse, that means you want a horse. If you want a white horse, you cannot get the brown and black horses; but if you want a horse, you can get the brown and black horses. So if you want a white horse, this doesn't mean you want a horse, therefore, a white horse is not a horse. Actually it just means that a white horse is a kind of horse, it doesn't represent all the horses. So white a horse is not a horse.

If white horse = horse
brown and black horse = horse

But brown and black horse do not equal white horse
Therefore white horse symbol does not equal horse

It's more like playing a trick with words, and it is not always correct.
For example:
Chinese is not Japanese
Chinese is Asian
This could lead you to believe that Japanese is not Asian (which is not correct).

Next: Legalism