If you dictate something, you say or read it aloud for someone else to write down.

If someone dictates to someone else, they tell them what they should do or can do.

If one thing dictates another, the first thing causes or influences the second thing.

You say that reason or common sense dictates that a particular thing is the case when you believe strongly that it is the case and that reason or common sense will cause other people to agree.

A dictate is an order which you have to obey.

Dictates are principles or rules which you consider to be extremely important.