rationales

Rationales are the sets of reasons and the logical basis for beliefs, decisions, policies, designs, or actions. The term comes from the Latin ratio, meaning reason or calculation, and in English it denotes the justification that underpins a conclusion or proposal. A rationale typically explains what problem is being addressed, why a particular approach is appropriate, what goals are intended, and how success will be evaluated. It may also reveal underlying assumptions, constraints, and expected trade-offs.

Rationales are used across many fields. In research and public policy, a rationale describes why a study or intervention is needed, what gaps it aims to fill, and the anticipated outcomes. In design and engineering, the design rationale documents the reasons for choosing a specific solution, the alternatives considered, the criteria used to decide, and the implications for implementation and maintenance. Design rationales often accompany requirements and decision records to support future changes.

Capturing rationales can take multiple forms, including narrative descriptions, decision logs, design rationale documents, or structured methods such as argument maps and traceability approaches. Effective rationales are explicit, evidence-informed, and linked to evaluation criteria or project requirements. They should clearly separate assumptions from conclusions and acknowledge uncertainty where it exists.

Rationales support accountability, transparency, and knowledge transfer by making the reasoning behind actions explicit. They help new team members understand past decisions and facilitate future revisits when conditions change.