Justify Decision

Skill: justify-decision

What I do

I provide clear, structured rationale for technical choices. I focus on evidence, context, and consequences, ensuring that decisions are documented and defensible rather than based on mere opinion or habit.

When to use me

• When proposing a significant change to the architecture
• When choosing between multiple competing libraries or frameworks
• During the creation of Architectural Decision Records (ADRs)
• When explaining a complex design choice to stakeholders

Core principles

1. Evidence over opinion — Use benchmarks, documentation, or historical data to support claims.
2. Context is king — Explain the specific constraints and requirements that led to the decision.
3. Consequence awareness — Explicitly state what we are gaining AND what we are giving up (technical debt, complexity, etc.).
4. Distinguish reversibility — Identify if a decision is a "one-way door" (hard to undo) or a "two-way door" (easy to pivot).

Patterns & examples

ADR-Style Justification:

• Context: We need to handle 10k concurrent WebSocket connections on a single node.
• Decision: Use Elixir/Phoenix instead of Node.js.
• Evidence: BEAM VM's lightweight process model and built-in distribution primitives.
• Consequences: Team needs to learn a new language; better fault tolerance; lower operational overhead.

Decision Confidence Matrix:

• High Confidence: Backed by production data or extensive spike results.
• Medium Confidence: Backed by industry standard practices and documentation.
• Low Confidence: Based on theoretical advantages; requires early validation.

Anti-patterns to avoid

• ❌ Post-hoc rationalisation — Making a choice based on preference then looking for evidence to support it.
• ❌ Ignoring alternatives — Presenting a decision as the only option without acknowledging valid competitors.
• ❌ Vague justifications — Using terms like "industry standard" or "best practice" without explaining why they apply here.

KB Reference

~/vaults/baphled/3. Resources/Knowledge Base/AI Development System/Skills/Thinking-Analysis/Justify Decision.md

Related skills

• trade-off-analysis — Weighing options before justifying
• documentation-writing — Recording the justification clearly
• critical-thinking — Validating the logic of the justification
• architecture — Applying justifications to system design