necessity-evaluation

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.