Paul Grice

"Strong freedom ensures that some actions are represented as directed to ends which are not merely mine, but which are also freely adopted or pursued by me."

"The maxim of quantity, where one tries to be as informative as one possibly can, and gives as much information as is needed, and no more."

"The maxim of quality, where one tries to be truthful, and does not give information that is false or that is not supported by evidence."

"The maxim of relation, where one tries to be relevant, and says things that are pertinent to the discussion."

"The maxim of manner, when one tries to be as clear, as brief, and as orderly as one can in what one says, and where one avoids obscurity and ambiguity."