System-level capability is a property of inter-component interaction, not of components in isolation, so per-component improvement does not compose into whole-system improvement. Ackoff states that when a system operates as well as possible, none of its parts may be operating as well as possible — implying an explicit design choice to accept locally suboptimal components in exchange for global behavior.
Directly challenges the standard agent-engineering practice of benchmarking and tuning each agent, tool, or prompt module to local best-in-class performance, then composing them. It predicts that per-component optimization can actively degrade end-to-end task performance, so evaluation budgets should be spent on interaction surfaces and end-to-end traces, not on module leaderboards.
Any composed system whose value emerges from interaction (multi-agent pipelines, tool chains, retrieval plus planner plus critic loops) cannot be validated by summing independent component scores; the unit of both design and evaluation is the interaction, not the part.
None of the parts has an independent effect on the whole.
Essential properties of any system derive from how its parts interact, not how they act separately.
When a system operates as well as possible, none of its parts may be operating as well as possible.
Improving the performance of parts taken separately does not necessarily improve the whole.