When something has coherence, all of its parts fit together well. An argument with coherence is logical and complete — with plenty of supporting facts.
Coherence comes from a Latin word meaning “to stick together." When you say policies, arguments and strategies are coherent, you’re praising them for making sense. Scientists are always looking for coherence in data to support their hypotheses. And coaches are always looking for coherence in their teams, so they don't fall apart.