Getting Things Done — David Allen

Summary

David Allen's GTD is the foundational system for personal productivity -- the "operating system" for knowledge workers. The core mental models:

1. Capture Everything, Decide Later. The fundamental insight is that your brain is for having ideas, not holding them. Capture all open loops -- things that need to get done, now or someday -- into a trusted external system. The inverse relationship: the more something is on your mind, the less it's getting done. Your brain nags you about things it doesn't trust will be handled.

2. Decide the Next Physical Action. Things rarely get stuck because of lack of time. They get stuck because "doing" hasn't been defined -- what the next physical visible action is, and where it happens. This is the conversion from amorphous "stuff" to actionable tasks.

3. Horizontal vs. Vertical Control. Horizontal control maintains coherence across all your projects and areas simultaneously -- the weekly review, the tickler file, the context lists. Vertical control manages the thinking and development of individual projects in depth. Both are necessary; most people only do one.

4. Principles Over Methods. Emerson's insight via Allen: "The man who grasps principles can successfully select his own methods. The man who tries methods, ignoring principles, is sure to have trouble." The system is not about a specific app or tool -- it's about the cognitive workflow beneath.

5. Incremental and Forgiving of Error. Approaches that forgive mistakes and allow course correction beat rigid systems long-term. The system should be resilient to imperfect execution, not dependent on it.

Relevance

• [[SOUL.md]] — The always-on agent architecture is essentially a GTD implementation. Capture inbound (inbox), clarify and process (triage), organize (vault structure), review (daily/weekly rhythms). The vault IS the trusted external system.
• [[06-reference/2026-04-03-the-e-myth-revisited]] — Allen's "next physical action" maps to Gerber's "operations manual." Both fight the same enemy: vague intentions that never become concrete work.
• [[06-reference/2026-04-03-shape-up-introduction]] — Shape Up's appetite-based scoping is vertical control applied to product teams. You define what "done" looks like before doing.
• [[06-reference/2026-04-03-engineer-manager-pendulum]] — The horizontal/vertical split mirrors the IC vs. manager tension. Managers need strong horizontal control; ICs need deep vertical focus.

Open Questions

• How does GTD adapt to AI-augmented workflows where the "trusted system" is itself an agent that can act on items?
• Is the weekly review still the right cadence in an always-on system, or should review be continuous?