| name | necessity-evaluation |
| description | Evaluate the probability of necessity (PN) for a causal factor — would the conclusion fail if this factor were absent? |
| execution | subagent |
| prompt | ./prompt.md |
| input | artifact (string), factor (string), conclusion (string) |
| dependencies | {"sops":["spawn-agent"]} |
Necessity Evaluation
Scores probability of necessity: P(Y would not hold | X absent).
Execution
Subagent — spawned via subagent-spawning/spawn-agent.
Why Subagent
Necessity evaluation requires careful counterfactual reasoning about absence, isolated from sufficiency judgments.
Input
- artifact: The original artifact
- factor: The factor to evaluate for necessity
- conclusion: The conclusion that may depend on this factor
Output
- pn_score: Probability of necessity (0.0–1.0)
- reasoning: Why this factor is/isn't necessary
- alternative_paths: Other ways the conclusion could hold without this factor
- confidence: Confidence in the PN estimate
Budget
One unit = one necessity evaluation per factor.
Available SOPs
Optional, no fixed order; the final leaf is always a sop.
| SOP | When to use |
|---|
| spawn-agent | Spawn a customized CC subagent with full MCP tool access. Used by SOPs that declare execution: subagent. |
