Truth! Information! Relevance! Clarity!

Gricean maxims
source: philosopher Paul Grice

• Maxim of Quality: Truth
• Do not say what you believe to be false.
• Do not say that for which you lack adequate evidence.
• Maxim of Quantity: Information
• Make your contribution as informative as is required for the current purposes of the exchange.
• Do not make your contribution more informative than is required.
• Maxim of Relation: Relevance
• Be relevant.
• Maxim of Manner: Clarity
• Avoid obscurity of expression. ("Eschew obfuscation")
• Avoid ambiguity.
• Be brief ("avoid unnecessary prolixity").
• Be orderly.