Thinking in Promises

Chapter 1. Promises and Impositions

Imagine a set of principles that could help you understand how parts combine to become a whole, and how each part sees the whole from its own perspective. If such principles were any good, it shouldn’t matter whether we’re talking about humans in a team, birds in a flock, computers in a data center, or cogs in a Swiss watch. A theory of cooperation ought to be pretty universal, so we could apply it to both technology and the workplace.

Such principles are the subject of Promise Theory. The goal of Promise Theory is to reveal the behaviour of a whole from the sum of its parts, taking the viewpoint of the parts rather than the whole. In other words, it is a bottom-up constructionist view of the world. You could describe it as a discipline for documenting system behaviours from the bottom up.¹

Promise Engineering

The idea of using promises as an engineering concept came up in 2004, as I was looking for a model of distributed computing to describe CFEngine. The word promise seemed a good fit for what I needed: a kind of atom for intent that, when combined, could represent a maintainable policy. However, it quickly became clear (having opened Pandora’s box on the idea) that there was something more general going on that needed to be understood about promises. Promises could also be an effective way of understanding a whole range of related issues about how parts operate as a whole, and it promised² something not previously taken seriously: a way ...