Gavin Kennedy aims to go beyond tough guy tactics to reveal how people actually negotiate. This text is not about what people ought to do, rationally or otherwise - it is about how people really behave and what you can do about it.
His thesis is that the two usual modes of negotiating behaviour should be blended. The "red style" is the use of manipulative tactics and agressive ploys, whilst the "blue style" is the antidote to this, suggesting the use of principled negotiation and rational problem solving prescriptions. Kennedy presents his "purple style", which says: "give me some of what I want ("red style") and I will give you some of what you want ("Blue style")". "Red" is taking behaviour, "blue" is giving behaviour, and "purple" is trading behaviour. "Purple" behaviour deals with people as they are, and not how you assume them to be. It is biased towards how negotiators behave and prefers the evidence of their behaviour to affirmations of their good intentions, but it is not a rationale for cynicism.
The author sets-out a simplified, 4-phase process of this theory: prepare; debate; propose; and bargain.