Statement
P03 Complexity belongs to the system
Just because it is complex to build does not mean it must be complex to use.
Tension
Explanation
When the interface mirrors the architecture, the person has to learn how the product was built before getting anything from it. That transfer seems inevitable only because it is convenient for the team.
Go deeper: Tension
When the interface mirrors the architecture, the person has to learn how the product was built before getting any value from it. That transfer usually seems inevitable only because it is convenient for the team.
Meaning
Explanation
The domain may require rules, integrations, and exceptions. The team absorbs that complexity and presents it as understandable decisions; internal tables and states do not dictate the language or navigation.
Go deeper: Meaning
The domain may require rules, integrations and exceptions. The team must absorb that complexity and present it as understandable decisions. Internal tables, states and services should not dictate the user's language or navigation.
Consequence
Explanation
Internal concepts are translated into the mental model of the person using the product. The system resolves what it can with the available context, and an exception is shown only to the person who actually must decide it.
Go deeper: Consequence
Translate internal concepts into the person's language and mental model.
Resolve dependencies, defaults and sequences where there is sufficient context.
Expose an exception only to those who genuinely have to decide it.
Example
A shipping service needs to know whether a package is domestic or international. Instead of asking, it infers this from the destination address and requests customs information only when applicable.
Counterexample
Opening an explanation with file paths, configurations, or commands before the person understands what they are for.
Sign of non-compliance. Asking the user to first choose an internal record type, where that distinction has no meaning for them, exposes the data schema as though it were a human need.
Decision test
These questions separate the steps that exist for the person from those that exist for the system.
Does this step exist because of a user need or because of the system's structure?
Are we showing a technical entity that could be translated or inferred?
Does the person need to understand this rule in order to make a good decision?
Source
Manifesto core v2.1, section PRINCIPLE 3 · P03. Download the core