I recall the first chapter of a novel which describes a certain alien race that can speak with two mouths, but one mouth can only speak the truth. This was about 15-20* years ago. Does anyone remember the name of this novel?
*Edit: correction, apparently, this was more recent than I remember.
This sounds like China Miéville's Embassytown, but that was published in 2011.
From Wikipedia:
Few people can speak the language of the Hosts (referred to only as "Language"), as it requires the orator to speak two words at once ... The Hosts' Language does not allow for lying or even speculation, the Language reflects both their state of mind and reality as they perceive it.
