Stress Testing

Finding the flaws before they find you.

When to Use

• Before committing engineering time

• Before choosing a roadmap direction

• Before betting on an architecture

• When evaluating a business proposal

• When something "feels risky" but you can't articulate why

Process

• Summarize the plan - Neutral wording, 2-4 bullets

• Extract assumptions - What must be true for this to work?

• Run pre-mortem - Imagine failure, work backward

• Build risk register - Likelihood, impact, mitigation

• Define kill criteria - When should we stop?

• Propose experiments - Cheap ways to validate

Output Contract

Structure every stress-test as:

Plan Summary

[2-4 bullets, neutral wording]

Must-Be-True Assumptions

Pre-Mortem: It's 1 Year Later, This Failed

Risk Register

Kill Criteria

• [Condition that should stop this plan]
• [Another stop condition]

Experiments to Run

• [Cheap test] - Success metric: [...]
• [Another test] - Success metric: [...]

Fundamental Questions

For Any Idea

• What would have to be true for this to work?

• What are we assuming that we haven't validated?

• What's the weakest link in this chain?

• If this fails, what's the most likely cause?

• Who has tried this before, and what happened?

For Claims

• What's the evidence?

• Is the source credible and disinterested?

• What would change my mind?

• What's the null hypothesis?

• Am I being told what I want to hear?

For Plans

• What's the first thing that will go wrong?

• What dependencies are we not seeing?

• What happens if it takes 2x longer or costs 2x more?

• Who's accountable if this fails?

• What's the rollback plan?

Pre-Mortem Technique

The Method

Imagine it's one year from now. The project has failed spectacularly. Now:

• What went wrong?

• What were the warning signs we ignored?

• What did we assume that turned out to be false?

• What did we not plan for?

• Who saw this coming and wasn't heard?

Why It Works

• Gives permission to voice concerns

• Overcomes optimism bias

• Surfaces hidden risks

• Generates specific failure modes

• Removes social pressure to be positive

Questions to Ask

• "What's the most likely way this fails?"

• "What's the most catastrophic way this fails?"

• "What assumption, if wrong, kills this?"

• "What's the thing we're not talking about?"

Common Failure Patterns

Planning Fallacies

• Optimism bias: Best case becomes the plan

• Anchoring: First estimate becomes the baseline

• Conjunction fallacy: Plan requires everything to go right

• Survivorship bias: We only see what succeeded

Ask: What if every step takes 50% longer? What if three things go wrong simultaneously?

Assumption Traps

• Untested assumptions: "Users will love this"

• Implicit assumptions: Things so obvious no one states them

• Stale assumptions: True once, maybe not now

• Borrowed assumptions: "That's how [BigCo] does it"

Ask: Can we list every assumption? Which have we actually validated?

Complexity Blindness

• Hidden dependencies: A needs B needs C needs...

• Integration risk: Parts work, whole doesn't

• Second-order effects: Solving X creates Y

• Coordination costs: More people ≠ faster

Ask: What's the real dependency graph? What happens at the interfaces?

Market Delusions

• "Build it and they will come": They won't

• "We just need 1% of the market": That 1% is fought over fiercely

• "No competition": Either you're wrong or there's no market

• "First mover advantage": Often means first to make mistakes

Ask: Who specifically will buy this? Why haven't they bought the alternatives?

Red Flags

In Communication

• "Trust me on this"

• "It's obvious that..."

• "Everyone knows..."

• "There's no downside"

• "This can't fail"

• "We'll figure it out later"

• Confident timelines for unprecedented work

In Planning

• No contingency budget (time or money)

• Single points of failure

• Success requires perfect execution

• No one is explicitly responsible

• Risks acknowledged but not mitigated

• "We'll move fast and iterate"

In Reasoning

• Confirming evidence only

• Dismissing counterexamples

• Moving goalposts

• Circular logic

• Appeal to authority without substance

• "It worked at [other company]"

In Teams

• No one plays devil's advocate

• Dissent is discouraged

• The loudest voice wins

• Sunk cost driving decisions

• Groupthink in action

• "We've always done it this way"

Stress Tests

The 10x Test

• What if usage is 10x what we expect?

• What if it takes 10x longer?

• What if it costs 10x more?

• What if we have 1/10 the resources?

The Adversary Test

• What would a competitor do to beat this?

• What would a malicious actor exploit?

• What would a hostile regulator target?

• What would a disgruntled user complain about?

The Scalability Test

• Does this work with 10 users? 1000? 1M?

• Does this work with 1 person? 10? 100?

• Does this work in 1 market? 10? 50?

• What breaks first at scale?

The Time Test

• Will this still make sense in 6 months?

• What changes in the environment could invalidate this?

• Are we building for now or for then?

• What's the shelf life of this decision?

The Dependency Test

• What external factors must remain true?

• What happens if [key partner] disappears?

• What happens if [key person] leaves?

• What happens if [key assumption] changes?

Constructive Skepticism

How to Challenge Without Crushing

• "Help me understand..."

• "What if we're wrong about..."

• "I want to stress-test this assumption..."

• "Let's imagine this fails—why did it fail?"

• "What would the skeptic in the room ask?"

Pairing Problems with Possibilities

• "This seems risky because X. Could we mitigate by Y?"

• "I'm worried about A. Have we considered B?"

• "This fails if C. What's our plan for C?"

Knowing When to Stop

• Don't block, flag

• Skepticism serves the decision, not itself

• Once risks are surfaced and considered, step back

• "I've raised my concerns; I'll support whatever we decide"

Biases to Watch

In Others

• Confirmation bias: Seeking only supporting evidence

• Sunk cost fallacy: Continuing because of past investment

• Availability heuristic: Overweighting recent or vivid examples

• Authority bias: Believing because of who said it

• Bandwagon effect: Believing because others do

In Yourself

• Contrarian bias: Disagreeing for its own sake

• Status quo bias: Favoring inaction

• Pessimism bias: Overweighting negative outcomes

• Negativity bias: Remembering failures more than successes

• Cynicism: Assuming bad faith

The Antidote

• "What would change my mind?"

• "Am I being skeptical or just negative?"

• "Is this a real risk or a rationalized fear?"

• "Have I given this idea a fair hearing?"

Decision Points

When to Kill an Idea

• Core assumption is invalidated

• Risk/reward is unfavorable

• Better alternatives exist

• Resources are better spent elsewhere

• The team doesn't believe in it

When to Proceed Despite Concerns

• Risks are known and accepted

• Mitigations are in place

• Upside justifies downside

• We'll learn something valuable either way

• Not deciding is worse than deciding

When to Investigate More

• Key assumptions are untested

• Risks are unclear

• We're missing information

• Expert opinion is divided

• Stakes are high

The Skeptic's Toolkit

Questions

• "What's the evidence?"

• "What are we assuming?"

• "What could go wrong?"

• "Who disagrees, and why?"

• "What would change our mind?"

Techniques

• Pre-mortem analysis

• Red team exercises

• Assumption mapping

• Risk registers

• Devil's advocate role

Outputs

• List of assumptions (tested/untested)

• Risk register with severity and likelihood

• Failure modes and mitigations

• Questions that need answers

• Conditions that would change the decision

The Balance

Skepticism Needs a Counterweight

• Dreaming without skepticism is fantasy

• Skepticism without dreaming is paralysis

• The goal is not to kill ideas but to strengthen them

• Some ideas should survive scrutiny

When to Switch Modes

• Dreaming phase: Suspend skepticism, expand possibilities

• Evaluation phase: Apply skepticism, test rigorously

• Execution phase: Skepticism becomes risk management

• Know which phase you're in

The Ultimate Test

A good skeptic asks:

• "Is this idea stronger for having been challenged?"

• "Are the remaining risks acceptable?"

• "Would a reasonable person proceed?"

If yes, the skeptic's job is done.

Mantras

• "What am I not seeing?"

• "Hope is not a strategy"

• "The market doesn't care about your intentions"

• "Reality is not optional"

• "Better to find the flaw than have it find you"

• "Strong opinions, loosely held"

• "Doubt is not disloyalty"

• "The goal is truth, not comfort"