The verb expostulate means to reason with someone against an intended course of action. Your parent you always expostulate about your really cool money-making ideas. They just don't understand!
Expostulate comes from the Latin word expostulare, meaning to demand urgently. The English word has lost its sense of demanding insistence. Synonyms for expostulate include object, protest, and remonstrate. Only expostulate, however, has the sense that the objection to the action and the argument against the action are offered in a friendly, reasonable manner. To expostulate is not to harangue into a different course of action, but to persuade.
