They search for the underlying meaning, how things are related. They become bored in highly structured situations. They are the dreamers. Imagination is important to them. When thinking is the dominant function, decisions are made in an impersonal way.
Dominant thinkers trust logic and strive to be objective.
They decide things by weighing the pros and cons and looking at the consequences. Truth is what's considered important. Feeling can also be used to make decisions. When feeling is the dominant function, decisions are made more with the heart than the head. Instead of truth, human values and harmony are what is most important.