The Principles and Their Purpose

The problem it addresses

Predictive delivery assumes requirements can be known upfront and will remain stable. Where that assumption holds, it works well. Where it does not — where the problem is poorly understood, the solution is uncertain, or the environment changes during delivery — a detailed upfront specification produces a precise plan for the wrong thing, discovered at the end.

Agile approaches address this by delivering in short cycles, each producing something usable, and adapting the plan based on what is learned.

The core values

• Individuals and interactions over processes and tools.
• Working output over comprehensive documentation.
• Customer collaboration over contract negotiation.
• Responding to change over following a plan.

The formulation matters: the items on the right have value, and the items on the left have more. This is consistently misread as "documentation is unnecessary" and "plans are unnecessary", which is not what it says and produces the chaotic delivery that gives agile a poor reputation in organisations that have tried it badly.

The underlying principles

• Deliver valuable output early and continuously.
• Welcome changing requirements, even late.
• Deliver working increments frequently, in weeks rather than months.
• Business people and delivery people work together daily.
• Build around motivated individuals and trust them.
• Face-to-face conversation is the most effective communication.
• Working output is the primary measure of progress.
• Maintain a sustainable pace indefinitely.
• Attend continuously to technical excellence and good design.
• Simplicity — maximising the work not done — is essential.
• Teams self-organise.
• Teams reflect regularly and adjust how they work.

Where it fits

Agile suits work where requirements are uncertain or evolving, feedback is available and useful, the cost of change is low, the business can engage continuously, and value can be delivered incrementally.

It fits poorly where requirements are genuinely fixed by regulation or contract, where the output cannot be delivered incrementally — a bridge, a refinery, a physical building — where the cost of change after construction is very high, or where the business cannot commit the continuous involvement it requires.

The honest position is that both approaches are tools, that the choice should follow the characteristics of the work, and that choosing by fashion is expensive in either direction.