Direct opposites:
* Compliment: Instead of a forceful, critical speech, a compliment is a positive remark.
* Praise: Similar to compliment, but often more elaborate.
* Encourage: To inspire and motivate, rather than scold or criticize.
Words that describe a gentler or more positive approach:
* Converse: To engage in a calm, respectful dialogue.
* Discuss: To talk about something in a reasoned and thoughtful way.
* Explain: To make something clear and understandable.
* Persuade: To convince someone through reasoned argument, rather than forceful speech.
The best antonym for "harangue" will depend on the specific context.