abductive-reasoning

abductive-reasoning is a skill for Claude Code, Codex from fzfclee/consulting-skills. It costs 49 tokens per session (708 once invoked), scanned A, original, Apache-2.0.

A reasoning method for choosing the most plausible explanation when facts are incomplete, unclear, or support several possibilities. It ranks explanations rather than proving one.

In plain words
What is it for?
Use it to compare competing explanations, identify missing evidence, and decide what information would change the conclusion.
Why use it?
It helps separate what the evidence actually supports from guesses when diagnosing an unexpected result or event.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to compare competing explanations, identify missing evidence, and decide what information would change the conclusion.

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Install with agentmods
npx agentmods add skills/fzfclee/consulting-skills/abductive-reasoning
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add fzfclee/consulting-skills --skill abductive-reasoning
Clone the repo
git clone --depth 1 https://github.com/fzfclee/consulting-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for abductive-reasoning

README.md
[![agentmods](https://agentmods.dev/badge/skills/fzfclee/consulting-skills/abductive-reasoning/github.svg)](https://agentmods.dev/skills/fzfclee/consulting-skills/abductive-reasoning)
Your own site
<a href="https://agentmods.dev/skills/fzfclee/consulting-skills/abductive-reasoning"><img src="https://agentmods.dev/badge/skills/fzfclee/consulting-skills/abductive-reasoning/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for abductive-reasoning

Your own site · 80×15
<a href="https://agentmods.dev/skills/fzfclee/consulting-skills/abductive-reasoning"><img src="https://agentmods.dev/badge/skills/fzfclee/consulting-skills/abductive-reasoning.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 708 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00049 $0.00708
Opus 5 $0.00024 $0.00354
Sonnet 5 $0.00010 $0.00142
Haiku 4.5 $0.00005 $0.00071

Measured 12d ago against content hash 4e5144b6b2d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

abductive-reasoning scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/abductive-reasoning/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Abductive Reasoning

Use this skill to choose the most plausible explanation when evidence is incomplete.

Method Notes

  • Abductive reasoning asks: what explanation would best account for the facts we see?
  • The output is a ranked explanation, not proof.
  • It is useful when stakeholder behavior, market signals, failures, or events can be explained in several ways.
  • A good abductive diagnosis names what each explanation explains, what it fails to explain, and what evidence would change the ranking.

Required Inputs

Collect or infer these inputs before execution:

  • surprising fact, event, behavior, or outcome
  • known evidence
  • candidate explanations
  • missing evidence
  • decision consequence if the explanation is wrong

If an input is missing, mark it as missing, state the assumption used, and add a validation action.

When Not To Use

Do not use when a formal rule already determines the conclusion. Use deductive-reasoning instead. Do not use when the task is broad pattern discovery; use inductive-reasoning first.

Step-by-Step Execution

Step Required input How to execute Output
State the puzzle Surprising fact or outcome. Define what needs explaining. Explanation question.
List evidence Facts, signals, timing, observations. Separate strong facts from interpretations and missing evidence. Evidence list.
Generate explanations Candidate causes, motives, mechanisms. Create plausible explanations without settling too early. Explanation candidates.
Score explanatory fit Evidence and candidates. Rate how well each explanation accounts for the facts, timing, and contradictions. Fit table.
Check parsimony and risk Candidates, assumptions, downside. Prefer explanations that require fewer unsupported assumptions, while noting high-risk alternatives. Plausibility ranking.
Identify discriminating evidence Top explanations. Define evidence that would clearly separate one explanation from another. Validation tests.
State working explanation Ranking and confidence. Choose the best current explanation and action implication. Working diagnosis.

Read the full file on GitHub · 77 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 77 lines · 49 tokens per session scan A 4e5144b6b2d4

Subscribe to this mod's changes

abductive-reasoning is a skill published in the GitHub repository fzfclee/consulting-skills (4 stars, last pushed 23d ago), licensed Apache-2.0. It adds 49 tokens to every session and 708 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.