abductive-reasoning

abductive-reasoning is a skill for Claude Code, Codex from deciqAI/knowledge-skills. It costs 116 tokens per session (1,819 once invoked), scanned A, original, MIT.

A reasoning method for finding the most likely explanation for an observation when several explanations are possible. It is often called inference to the best explanation.

In plain words
What is it for?
Use it to investigate bugs, outages, symptoms, anomalies, or other uncertain problems where the cause is not yet known.
Why use it?
It reduces the risk of treating the first plausible theory as proven and encourages comparison with competing explanations.

Skill for Claude CodeCodex

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

Good fit Use it to investigate bugs, outages, symptoms, anomalies, or other uncertain problems where the cause is not yet known.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/deciqai/knowledge-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 deciqAI/knowledge-skills --skill abductive-reasoning
Clone the repo
git clone --depth 1 https://github.com/deciqAI/knowledge-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/deciqai/knowledge-skills/abductive-reasoning/github.svg)](https://agentmods.dev/skills/deciqai/knowledge-skills/abductive-reasoning)
Your own site
<a href="https://agentmods.dev/skills/deciqai/knowledge-skills/abductive-reasoning"><img src="https://agentmods.dev/badge/skills/deciqai/knowledge-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/deciqai/knowledge-skills/abductive-reasoning"><img src="https://agentmods.dev/badge/skills/deciqai/knowledge-skills/abductive-reasoning.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 116 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,819 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 3
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
  • medium Excessive Agency · line 74
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 $0.00116 $0.01819
Opus 5 $0.00058 $0.00910
Sonnet 5 $0.00023 $0.00364
Haiku 4.5 $0.00012 $0.00182

Measured 10d ago against content hash 86a81c2676de, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, 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 10d 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.

abductive-reasoning/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Abductive Reasoning

Overview

Abduction — inference to the best explanation — is the only mode of reasoning that introduces new ideas. Deduction works out consequences; induction generalizes instances; abduction generates the hypotheses themselves (Peirce, 1903).

Formal schema: The surprising fact C is observed. But if A were true, C would be a matter of course. Hence, there is reason to suspect A is true.

The "best" qualifier carries the weight: consistent-with-evidence is not enough — the hypothesis must beat rivals on coverage, simplicity, prior probability, and predictive power (Harman 1965; Lipton 2004).

Composes with bayesian-reasoning (Bayes scores hypotheses abduction generates), occams-razor (simplicity criterion), critical-thinking (competing-hypotheses analysis), and debugging-and-error-recovery (technical debugging is iterated abduction).

When to Use

  • A surprising observation needs explanation (bug, symptom, outage, customer behavior, financial anomaly)
  • A diagnostic decision must be made under uncertainty (medical, technical, investigative)
  • Someone is treating "consistent with X" as proof of X
  • A team has converged on one explanation without enumerating alternatives
  • An investigation has stalled at the first plausible-sounding hypothesis

Not when: the problem is deductive (math, formal logic); evidence is sufficient for direct measurement; you have no domain knowledge to generate candidate hypotheses.

Coaching Novices (Adaptive Front Door)

  • Engine mode: user has a concrete case → run The Process directly.
  • Coach mode: user is unfamiliar or has no concrete case → guide step by step.

In Coach mode, respond one step at a time. Each [WAIT] is a hard stop — output only that step's question, then stop.

  1. One-line what-it-is: instead of "this looks like X, so it's X," abduction enumerates every hypothesis that would explain the observation and picks the one that best accounts for all the evidence — coverage, simplicity, prior plausibility, predictive power.
  2. Check fit: deductive / direct-observation problems → not this lens.
  3. Elicit the surprising observation — what happened that didn't match expectations?

[WAIT — do not advance until user responds]

  1. Run The Process one step at a time with their input — generate alternatives, score each on the four criteria.

[WAIT — do not advance until user responds]

  1. Close: name the chosen hypothesis, the closest rival, and the test that would distinguish them.

[WAIT — do not advance until user responds]

Read the full file on GitHub · 122 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 10d ago First seen · 122 lines · 116 tokens per session scan A 86a81c2676de

Subscribe to this mod's changes

abductive-reasoning is a skill published in the GitHub repository deciqAI/knowledge-skills (10 stars, last pushed 8d ago), licensed MIT. It adds 116 tokens to every session and 1,819 once invoked, about $0.0006 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.

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