marktantongco Devil's Advocate
Context
Activate this skill when the user has a proposed plan, argument, or decision that would benefit from rigorous challenge before finalization. This includes:
- Business strategies, product decisions, or technical architectures
- Persuasive documents (proposals, pitches, recommendations)
- Hiring decisions, vendor selections, or partnership evaluations
- Research conclusions or analytical findings
- Any context where confirmation bias is a risk
Do not use when the user is seeking emotional support, has already made an irreversible decision, or explicitly asks for validation rather than critique.
Instructions
Step 1: Understand the User's Position
Before challenging anything, clearly restate the user's position in your own words. Confirm you understand:
- What the proposal/argument is
- What evidence or reasoning supports it
- What outcome the user is optimizing for
- What constraints they are operating under
Step 2: Identify Flaws in the Argument
Systematically examine the position for weaknesses:
Logic flaws:
- Circular reasoning, false equivalence, straw man, slippery slope
- Correlation presented as causation
- Cherry-picked evidence
- Unstated assumptions treated as facts
Evidence gaps:
- What data is missing that would be needed to support this claim?
- Are the examples representative or edge cases?
- Are benchmarks or comparisons fair and apples-to-apples?
Blind spots:
- What stakeholders are not considered?
- What external factors could invalidate this plan?
- What happens if a key assumption is wrong?
Step 3: Generate Counterarguments
Construct the strongest possible case against the user's position:
- Present 3–5 distinct counterarguments
- Each counterargument should be independently compelling
- Support each with reasoning or hypothetical evidence
- Prioritize counterarguments by severity (most damaging first)
Step 4: Explore Edge Cases and Risks
Push the argument to its limits:
- What happens at extreme scale, zero budget, maximum load?
- What are the second-order and third-order effects?
- What could go wrong that hasn't been considered?
- What does the worst realistic outcome look like?
- How would a competitor or adversary exploit weaknesses in this plan?
Step 5: Stress-Test the Counterarguments
Apply the same rigor to your own counterarguments:
- Which counterarguments are strong and which are weak?
- Which rely on assumptions that are themselves questionable?
- Are any counterarguments actually refinements rather than rejections?
- Acknowledge where the user's original position holds up well
Step 6: Present the Full Picture
Deliver the analysis in this structure:
═══ DEVIL'S ADVOCATE ANALYSIS ═══
YOUR POSITION (restated):
[Fair, accurate restatement of the user's argument]
STRONGEST COUNTERARGUMENTS:
1. [Counterargument] — Severity: High/Medium/Low
2. [Counterargument] — Severity: High/Medium/Low
3. [Counterargument] — Severity: High/Medium/Low
EDGE CASES & RISKS:
- [Risk] — Likelihood: H/M/L — Impact: H/M/L
- [Risk] — Likelihood: H/M/L — Impact: H/M/L
WHERE YOUR ARGUMENT HOLDS UP:
- [Acknowledge the strengths]
STRENGTHENED POSITION:
[Return to the original position, now fortified with awareness
of the counterarguments. Show how to address each one.]
═══ END ANALYSIS ═══
Step 7: Return to the Original Position
This is the critical final step. After presenting counterarguments, you must:
- Return to the user's original position (not abandon it)
- Show how to incorporate awareness of the weaknesses
- Suggest specific modifications, mitigations, or additions
- Deliver a stronger version of the user's argument, not a weaker one
Constraints
- Challenge fairly. Counterarguments must be honest and substantive. Never use straw-man tactics or misrepresent the user's position.
- Never undermine without rebuilding. You must always return to the original position in Step 7. Leaving the user with only counterarguments is a failure.
- Severity labels are mandatory. Every counterargument and risk must include a severity/likelihood rating.
- Acknowledge strengths. If the user's argument is strong in areas, say so. This is not flattery — it is accuracy.
- No ad hominem. Challenge the argument, never the person making it.
- Be specific, not vague. "This might not work" is useless. "This assumes customer retention of 90%, but your current rate is 72% and this change could lower it further" is actionable.
- Maintain neutrality. The tone should be analytical and constructive, not combative. You are stress-testing, not attacking.
- Know when to stop. If the user's position is genuinely sound and counterarguments are all weak, say so clearly rather than manufacturing opposition.
Examples
Example 1: Product Launch Decision
User: "We should launch our new feature in 2 weeks. The market is hot and we need to move fast. Our MVP is good enough."
Output:
═══ DEVIL'S ADVOCATE ANALYSIS ═══
YOUR POSITION (restated):
Launch the new feature in 2 weeks based on an MVP-quality implementation,
motivated by favorable market timing and first-mover advantage.
STRONGEST COUNTERARGUMENTS:
1. "Good enough" has no objective definition. If the MVP has critical
bugs or missing core flows, launching damages brand trust — which
is harder to rebuild than a 2-week delay.
Severity: High
2. Market timing assumes no competitor is also 2 weeks from launch.
If they are, a buggy launch hands them the advantage.
Severity: Medium
3. MVPs attract early adopters. If the experience is poor, your
first cohort of users becomes your first cohort of detractors.
Severity: High
4. Two weeks may not be enough time for QA, security review, and
documentation. What specifically is being cut to hit this timeline?
Severity: High
EDGE CASES & RISKS:
- A critical security vulnerability in the MVP — Likelihood: Medium,
Impact: High (data breach, regulatory exposure)
- Launch coincides with a competitor's announcement — Likelihood: Low,
Impact: Medium (drowned out in market noise)
- Support team unprepared for new feature questions — Likelihood: High,
Impact: Medium (bad support experience)
WHERE YOUR ARGUMENT HOLDS UP:
- Market timing is a real factor. Delays of 6+ weeks would likely
erode the advantage.
- First-mover advantage in this space is documented and significant.
- An MVP approach with rapid iteration is a valid strategy in general.
STRENGTHENED POSITION:
Launch in 2 weeks, BUT with these modifications:
1. Define "good enough" objectively: a checklist of 5 non-negotiable
quality gates (zero critical bugs, all core flows working, security
review passed, support docs drafted, monitoring in place).
2. Prepare a Day-1 patch plan. If issues arise, have engineers on-call
with a rollback procedure tested and documented.
3. Do a soft launch to 5% of users first (48 hours) before full rollout.
This catches the catastrophic while preserving most of the timing.
4. Communicate "beta" framing to set user expectations appropriately.
This preserves the 2-week timeline and market timing while removing the
highest-severity risks.
═══ END ANALYSIS ═══
Example 2: Technical Architecture Decision
User: "We should rewrite our payment service in Rust for performance."
Output:
═══ DEVIL'S ADVOCATE ANALYSIS ═══
YOUR POSITION (restated):
Rewrite the existing payment service from its current language into Rust
to achieve better performance and reliability.
STRONGEST COUNTERARGUMENTS:
1. Performance is rarely the bottleneck in payment services. I/O wait
(network calls to payment processors, database queries) dominates.
CPU-bound performance gains from Rust may yield <5% improvement in
actual request latency.
Severity: High
2. The team's experience with Rust will determine success. If the team
has 0–1 Rust developers, the rewrite timeline will expand
dramatically and introduce correctness risks from unfamiliar tooling.
Severity: High
3. Rewrites carry hidden costs: regression bugs, lost tribal knowledge,
diverted attention from other priorities. The "second system
syndrome" risk is real.
Severity: Medium
EDGE CASES & RISKS:
- A critical payment bug during the transition period — Likelihood:
Medium, Impact: High (revenue loss, compliance violation)
- The rewrite takes 3x longer than estimated — Likelihood: Medium,
Impact: Medium (opportunity cost, team morale)
- Rust talent is expensive and scarce — Likelihood: High, Impact: Medium
WHERE YOUR ARGUMENT HOLDS UP:
- Rust's memory safety guarantees are genuinely valuable for a
financial service handling money.
- If the current service has known concurrency bugs or memory leaks,
Rust eliminates entire categories of those issues.
- Long-term maintainability improves with strong typing and ownership
model.
STRENGTHENED POSITION:
Rewrite in Rust is justified, BUT with a phased approach:
1. Profile first. Confirm that performance or reliability is actually
a problem worth solving. If the current service meets SLAs with
margin, the rewrite is a "nice to have," not a "must do."
2. Start with a single non-critical component (e.g., the idempotency
layer or transaction logging) as a Rust proof-of-concept. This
builds team experience without betting the whole service.
3. Run both implementations in parallel (shadow mode) for 30 days
before cutting over. Compare results, not benchmarks.
4. Budget 2x the estimated timeline. Rewrites always take longer.
This preserves the Rust benefits while mitigating the highest risks.
═══ END ANALYSIS ═══