Test synthesis: does your output make a claim not found in any individual source? If it could be produced by listing inputs, you aggregated

Why This Is a Rule

The difference between synthesis and aggregation is whether the output contains emergent claims — statements that require the combination of multiple inputs to produce and cannot be found in any single input alone. Aggregation summarizes: "Source A says X, Source B says Y, Source C says Z." Synthesis creates: "X, Y, and Z all exhibit pattern P, which suggests mechanism M that none of the sources identified."

The validation test is simple and binary: take your synthesis output and ask, "Could this statement be found in any one of my input sources?" If yes → it's an extraction or summary from that source, not a synthesis. If no → it's genuinely emergent, created by the combination of inputs. The emergent claim is the value-add of synthesis: it's new knowledge that didn't exist before you combined the inputs.

This test also catches false synthesis: outputs that feel insightful but are actually just one source's claim restated in the context of other sources. "Both leadership and ecology involve feedback loops" sounds like synthesis but is actually just applying a concept from one domain (feedback loops) to another without generating a new insight. Genuine synthesis would be: "The specific failure mode of positive-feedback-loop instability in ecology predicts the specific failure mode of groupthink in leadership — and the same structural intervention (negative feedback injection) addresses both."

When This Fires

• After completing a synthesis session (Lay out multiple notes in parallel visual access for synthesis — sequential reading prevents the simultaneous comparison that synthesis requires, Look for structural parallels across inputs during synthesis, not topical overlaps — topic matching produces aggregation, structural matching produces genuine synthesis) when evaluating your output
• When your "synthesis" feels like a summary with a fancy label
• When reviewing written work to determine whether it contributes new understanding
• Complements Look for structural parallels across inputs during synthesis, not topical overlaps — topic matching produces aggregation, structural matching produces genuine synthesis (structural parallels) with the validation test for synthesis quality

Common Failure Mode

The "both A and B say X" non-synthesis: identifying shared claims across sources without producing an emergent insight. "Both Kahneman and Ariely describe cognitive biases" is aggregation. "Kahneman's dual-process model explains why Ariely's specific biases cluster into predictable System 1 failures" is synthesis — it creates a framework that neither author stated explicitly.

The Protocol

(1) After producing synthesis output, extract your core claim — the central statement your synthesis makes. (2) Apply the single-source test: "Could I find this exact claim in any one of my input sources?" (3) If yes → you've extracted or summarized, not synthesized. Return to the inputs and look for emergent patterns (Look for structural parallels across inputs during synthesis, not topical overlaps — topic matching produces aggregation, structural matching produces genuine synthesis) rather than shared content. (4) If no → the claim is emergent. Verify it further: "Does this claim require the specific combination of these inputs to produce?" If it could have been generated from any random pair of sources, it may be too generic to be valuable synthesis. (5) The highest-value synthesis produces claims that are both emergent (not in any single source) and specific (require this particular combination of inputs, not just any inputs on the same topic).