Collective fallacies field guide
What goes wrong when more than one mind is involved: 253 entries in twenty families, each marked with what actually stands behind it.
A group is not a mind with more information. It is a mechanism, and it has failure modes of its own.
Nothing here is explained by the people in the room being biased. Each of these failures is available to a room of careful, well-intentioned, individually rational people.
Twenty families, seven parts, one tag on every entry
The families group entries by the mechanism they share rather than by the setting they are usually met in, so an incentive failure in a school system sits beside the same failure in a hospital and a bank. The A to Z index is Appendix A, where every row links to its entry.
What stands behind it
The six are mutually exclusive and decided in that order reversed: is it advice, is it a derivation, is it a proposed structure, is it a named regularity — and only if it is none of those does the empirical record decide between replicated and disputed.
A third of it is models
Counted honestly, and printed on the opening slide rather than buried in the limits: this is what the collection is made of.
Where the weight sits
Targets, agreement and projects carry a fifth of the guide between them — which is a fact about where organisations actually go wrong.
A bias is something that happens to you. A fallacy of this kind is something a structure does to everyone in it.
The practical consequence is what to do on finding one. A bias is answered by changing what the person meets: the default, the format, the sequence, the time available. A collective fallacy is answered by changing what the group is: who is in the room, what order they speak in, what the measure is attached to, who can stop the work, and what happens to the person who says the uncomfortable thing.
Nobody in the room has to be wrong for the room to be wrong
That is the whole subject. Every entry here is a way for careful people, each behaving reasonably, to produce an outcome none of them would have chosen.
The room
What happens when people decide together, and how a group reaches a position none of its members holds.
How a group reaches a position none of its members holds
The room agrees, the decision is taken, and afterwards nobody can find the person who wanted it.
Abilene paradox
A group can take a course of action that every member privately opposes, because each mistakes the silence of the others for agreement.
Pluralistic ignorance
A group sustains a norm that most of its members privately reject, because each believes the others accept it.
Preference falsification
People state a public position they do not hold in order to avoid social cost, so public opinion can diverge sharply and invisibly from private opinion.
Spiral of silence
People who believe their view is losing ground in public become less willing to express it, which makes the view appear weaker still.
The emperor’s new clothes
When admitting the obvious would mark a person as incompetent or disloyal, a plainly false claim can be maintained in public by everyone at once.
The common-knowledge problem
Coordinated action often requires not merely that everyone knows a fact, but that everyone knows that everyone knows it, and no exchange of fallible messages can establish that.
Groupthink
A cohesive group under pressure is said to suppress dissent and converge early on a course of action worse than any member would have chosen alone.
Group polarisation
After discussing an issue with like-minded others, people hold more extreme versions of the views they arrived with.
Risky shift
Groups were long held to take riskier decisions than their members would take alone, a claim the later evidence did not sustain.
Hidden profiles
When the information needed for the best decision is divided among members, groups discuss what they already share and miss the answer.
The devil’s advocate paradox
Dissent that is assigned rather than felt reassures a group without changing its mind.
HiPPO effect
Where evidence is thin or unwelcome, the question is settled by the most senior person in the room.
Authority gradient
The steeper the perceived power difference in a team, the less likely the junior member is to say what they have seen.
Asch conformity
People will state an answer they can see is wrong when everyone ahead of them has stated it.
Milgram obedience
Ordinary people continued to deliver what they believed were dangerous shocks because a man in a laboratory coat asked them to.
Deindividuation
Anonymity does not release restraint so much as hand control of behaviour to whatever the local norm happens to be.
False consensus in groups
Members of a group over-estimate how many colleagues share their reading of a decision, and score silence as agreement.
What happens to work as the group grows
Adding people to a task changes who is answerable for it, and the arithmetic is not what the headcount suggests.
Social loafing
Individual effort falls as a group grows, whenever no one can see who contributed what.
Free-rider problem
When a benefit cannot be withheld from those who do not pay for it, the rational move is to let someone else pay.
Sucker effect
People withdraw effort not from laziness but to avoid being the one who carries someone who is not pulling.
Bystander effect
The more people who witness a situation that calls for help, the less likely any one of them is to act.
Collective action problem
A group of people who all want the same outcome will not act to produce it, because each does better letting the others pay for it.
Coordination neglect
Organisations divide work competently and then fail to put it back together, because division is visible and integration is not.
Bikeshedding
A committee will spend more time on the item it understands than on the item that matters.
Dunbar’s number
A cognitive limit of about 150 is said to cap the number of stable relationships a person can hold, and so the size of any group that runs on relationships alone.
Social facilitation
The presence of other people speeds up performance on a task you have mastered and degrades it on one you have not.
Accountability sinks
A structure that breaks the link between a decision and anyone who can be asked about it, so complaints arrive nowhere.
Meeting cost blindness
The cost of a meeting is the time of everyone in it, and no budget records that, so meetings are treated as free.
What reaches the top, and what does not
Every layer between the work and the decision is a place where bad news can be softened, delayed or stopped.
MUM effect
People withhold bad news from those it concerns, even when they had nothing to do with it and no reason to fear blame.
Shooting the messenger
The bearer of bad news is judged worse for having borne it, and everyone watching learns not to be next.
Organisational silence
Organisational silence is the collective withholding of concerns and dissent, produced by shared beliefs about what it is safe to say rather than by individual timidity.
Psychological safety
Psychological safety is a belief shared within a team that speaking up with a question, a doubt or an admitted error will not be held against you.
The error-reporting paradox
Where reporting is safe, reported error rates rise, so a falling error count is as likely to mean that people have stopped telling you as that the work has become safer.
Watermelon reporting
A programme is reported green at every level while the work underneath it is red, because each reviewer rates the report rather than the thing.
Upward filtering
Each layer of a hierarchy passes on the version of events it can defend, so the account that reaches the top is not the account that was sent.
Semmelweis reflex
An institution rejects a finding, and often the person who brought it, because accepting it would indict the practice the institution already follows.
The whistleblower’s dilemma
The person who reports serious wrongdoing carries the cost alone while the benefit is spread across everyone else, which is why most people who see it say nothing.
Sycophancy
Agreement supplied upward because it is rewarded, which leaves a leader with a record of confirmation and no record of dissent.
Information hoarding as power
Where one person or unit is the only route to something the organisation needs, withholding it is a rational way to hold position.
The measure
What a number does once it becomes a target, what payment does to willingness, and the games structure forces on rational people.
What a number does once it becomes a target
The largest family in the guide, and the one a school system meets most often.
Goodhart’s law
A measure that was informative while nobody was trying to move it stops being informative once people are required to move it.
Campbell’s law
The more a quantitative indicator is used to make decisions, the more it will be corrupted and the more it will distort the process it was meant to monitor.
Lucas critique
A relationship estimated under one policy regime cannot be used to predict what a change of regime will do, because the behaviour that produced it will change too.
Surrogation
People replace the thing they care about with the measure of it, and then stop being able to tell the difference.
Metric fixation
The belief that measurement can replace judgement, that published numbers secure accountability, and that people are best motivated by rewards tied to those numbers.
McNamara fallacy
Measure what is easy, disregard what is not, then treat what cannot be measured as unimportant and finally as non-existent.
Cobra effect
A reward offered for reducing something creates a supply of the thing, so the scheme increases what it was meant to suppress.
Ratchet effect
When current output sets the next target, people hold back: good work today is paid for with a harder standard tomorrow.
Rewarding A while hoping for B
Organisations routinely pay for one behaviour while hoping for another, and then are surprised to get the one they paid for.
Teaching to the test
Instruction moves toward the specific form of the examination, so scores rise faster than the learning they are supposed to represent.
Curriculum narrowing
Time and attention move to the tested subjects, so the curriculum shrinks to the shape of the accountability measure.
Cream-skimming
When performance is judged on outcomes, providers raise the average by selecting the cases most likely to succeed and quietly shedding the rest.
The audit society
An account of how checking spreads until organisations reshape their work to produce the traces an auditor can verify, and verification of the traces replaces knowledge of performance.
Tick-box compliance
Organisations adopt the visible form of a requirement while the practice it was meant to change stays exactly where it was.
The benchmarking trap
Copying the practices of measured high performers makes organisations more alike without making them better, because the practices were never what produced the performance.
League-table effects
Publishing ranked institutional results changes behaviour inside the institutions, improving the published measure and pulling effort towards whoever sits nearest the line.
Simpson’s paradox
An association present in every subgroup can reverse when the subgroups are pooled.
Ecological fallacy
An association measured between groups need not hold, and can reverse, for the individuals inside them.
What payment does to willingness
Paying for something that was being done freely can cost more than the payment.
Overjustification effect
Rewarding an activity someone already chose to do can reduce the chance they choose it again once the reward stops.
Motivation crowding-out
Paying people for something they were doing out of duty, reciprocity or identity can reduce how much of it they do.
The fine that became a price
A penalty attached to a behaviour can license it, by converting a moral obligation into a service with a stated price.
Pay-for-performance failure
Paying for measured output reliably raises the measured output, and reliably degrades everything the measure leaves out.
Forced ranking
Grading a workforce against a fixed distribution and cutting the bottom band, a practice whose claimed benefits rest largely on simulation rather than measurement.
Non-promotable tasks
Work that has to be done but earns nobody a promotion, distributed not by skill but by who is expected to say yes.
Presenteeism
Attending work while ill, produced by the structure of cover and absence rules rather than by dedication.
Effort withdrawal
The response to a perceived unfairness that neither complains nor leaves, but quietly reduces what is given.
Misreading what motivates others
People believe others are moved by money and security while believing themselves moved by interest and mastery.
Bad outcomes from rational players
Not a failure of judgement. A structure in which every individually sensible move adds up to a worse result for everyone.
Prisoner’s dilemma
A two-player game in which defection pays better than cooperation whatever the other side does, leaving both worse off than if both had cooperated.
Stag hunt
A game with two stable outcomes — everyone cooperates, or everyone plays safe — in which the safe outcome can win despite being worse for all.
Chicken and brinkmanship
A contest in which a threat works only if the other side believes you will not back down, so the advantage goes to whoever can visibly destroy their own ability to back down.
Tragedy of the commons
The claim that a shared resource is inevitably destroyed by its users unless it is privatised or policed, which holds for open access and not for commons.
Ostrom’s design principles
Commons institutions that last for generations share eight design features, most of which work by making monitoring cheap and defection visible.
Tragedy of the anticommons
When too many parties each hold a right to exclude, a resource is used far too little, which is the mirror image of the commons.
Moral hazard
Once someone else carries the cost of an outcome, the party who controls it takes less care, and no bad faith is required.
Adverse selection
When one side knows more about quality or risk than the other, the better-than-average side withdraws and the market can unravel to nothing.
Principal–agent problem
When one party acts for another, cannot be fully observed and does not share its objectives, no contract removes the resulting loss; it can only be traded against risk.
Rent-seeking
Where a prize can be won by effort rather than earned by production, the effort spent competing for it is pure loss, and it can consume the whole prize.
Concentrated benefits, diffuse costs
A small group with a large stake each will organise; a large group with a small stake each will not, so policy tilts towards the few even when the many lose more in total.
Arms-race dynamics
Each side arms because the other has, so both spend heavily and neither ends up safer than it began.
Red Queen effect
Everyone improves, so nobody gains: effort rises across a whole field while relative position stays exactly where it was.
Winner’s curse
In a contest for something of uncertain but common value, the winner is usually the bidder who overestimated it by the most.
The structure
What organisations do to themselves over time, how the shape of the work follows the shape of the chart, and what gets done to be seen being done.
What organisations do to themselves over time
The named laws: what they claim, where they came from, and why they are believed without ever having been tested.
Parkinson’s law
Work expands to fill the time available for it, and administrative staff grows at a rate largely unrelated to the work there is to do.
Peter principle
Promotion on performance in the current job moves people up until they reach one they cannot do, and there they stay.
Dilbert principle
Poor performers are moved into management because that is where they can do least damage to the work.
Putt’s law
Technical organisations divide into those who understand what they do not manage and those who manage what they do not understand.
Pournelle’s iron law of bureaucracy
In any bureaucracy, those devoted to the organisation itself come to control it, and those devoted to its stated purpose lose influence.
Iron law of oligarchy
Any organisation large enough to need full-time officials tends to be run by them, though the evidence makes this a tendency rather than the iron law Michels claimed.
Shirky principle
Organisations come to protect the problem that justifies their existence.
Goal displacement
A procedure adopted to achieve an end becomes the end, and is defended even where it no longer serves the purpose.
Trained incapacity
The training that makes people competent in the normal case is what stops them seeing the abnormal one.
Rule accretion
Rules are added faster than they are removed, so procedure accumulates until the burden bears little relation to the risks that produced it.
Founder’s syndrome
The habits and informal authority that let a founder build an organisation become the constraint on it once the organisation outgrows what one person can hold.
Span of control
The number of people reporting to one manager fixes how many layers an organisation needs, and the classical answer of five or six was a doctrine rather than a measurement.
The silo effect
Units created to specialise acquire their own goals, measures and vocabulary, and then withhold from each other the information that only the whole organisation can use.
Coordination cost
Each person added to a group adds more links than hands, so the cost of keeping everyone aligned grows faster than the group does.
The budget-maximising bureau
An agency that is the sole supplier of its output to a sponsor who cannot see its costs can secure a budget well above what the service requires.
Structure showing through in the product
The thing an organisation builds ends up shaped like the organisation that built it, whatever the design said.
Conway’s law
Any organisation that designs a system will produce a design whose structure copies the communication structure of that organisation.
The inverse Conway manoeuvre
Since structure shapes architecture, move the team boundaries first and let the system you want follow.
Brooks’s law
Adding people to a late software project makes it later.
The mythical man-month
The man-month is a unit that assumes people and time can be traded for one another, which holds only for work that requires no communication.
Second-system effect
The second system a designer builds is the most dangerous, because it collects every embellishment the first one had no room for.
Bus factor
The number of people who would have to leave before the work could not be carried on, and a warning that the number is usually smaller than anyone thinks.
Not-invented-here
A group discounts knowledge, tools or solutions because they came from outside it, and pays to rebuild what it could have adopted.
Cargo cult
Copying the visible forms of a successful practice while missing the mechanism that made it work, and expecting the results to follow.
Innovation theatre
Activity that displays innovation — labs, hackathons, accelerators, sprints — while the budgets, procurement rules and decision rights that would let anything new be adopted stay exactly as they were.
Compliance and security theatre
Measures that produce the appearance of safety or compliance for an audience while doing little to the risk they are said to address.
Work-as-imagined and work-as-done
The work as described in procedures and the work as actually done diverge, because a procedure cannot contain all the variability the work contains.
Practical drift
Groups quietly adapt written procedure to the conditions they usually face, and the adaptations only collide on the day the groups are coupled tightly together.
Technical debt
A shortcut taken to ship sooner leaves a structure that costs more to change, and the extra cost is paid on every later change until it is repaid.
The big-bang rewrite
Replacing a working system wholesale rather than piece by piece trades a known set of defects for an unknown one, and buys an interval in which nothing ships.
Doing things to be seen to be doing them
Organisations adopt structures because adoption is what a credible organisation does, not because the structure works.
Institutional isomorphism
Organisations in the same field come to resemble one another, not because the shared form works better, but because resemblance secures legitimacy and resources.
Ceremonial conformity and decoupling
Organisations adopt the structures their environment rewards and then insulate the real work from them, so policy and practice run on separate tracks.
The best-practice cargo cult
Copying the visible practices of a successful organisation imports the form without the conditions that made it work, and the conditions are usually what mattered.
Policy-based evidence
Evidence is commissioned, selected and timed to support a decision already taken, so the appearance of an evidence base survives while its function does not.
Performativity
A theory of human behaviour can make itself true, because people use it to act, and the world then moves towards the model rather than the model towards the world.
The garbage-can model
Where goals are unclear and attention is scarce, decisions are made by the chance meeting of problems, solutions, participants and occasions rather than by anyone solving anything.
Vetocracy
When enough actors hold a right to block and none holds a right to decide, the status quo wins by default and reform is bought rather than chosen.
Kludgeocracy
Because layering a new rule on the old ones is politically cheaper than replacing them, policy accumulates complexity, and the cost of that complexity is paid in citizens’ time.
Regulatory capture
An agency created to regulate an industry comes to act in that industry’s interest, not usually through corruption but because the industry is the only constituency that turns up.
The revolving door
Officials move between government and the industries they oversee, and while the connections they carry have a measurable price, the softened enforcement usually attributed to the door has been hard to find.
Bootleggers and Baptists
Durable regulation usually needs two coalitions: one that argues for it on moral grounds in public, and one that profits from it quietly.
The iron triangle
A legislative committee, an agency and an organised interest can close a policy area to outsiders, because each holds something the other two need.
The change
The reformer’s traps, the systems that push back, and why the business case is never the outcome.
The reformer’s traps
Every one of these is a way of being right about the problem and wrong about what removing it will do.
Chesterton’s fence
Do not remove a rule or a structure until you can say what it was put there to do.
The sources of unintended consequences
Purposive action produces outcomes nobody intended, and those outcomes come from a small number of sources that can be listed in advance.
Legibility and high modernism
A state must simplify what it administers into categories it can read, and when the simplification is then imposed as a design, it destroys what made the thing work.
Metis and techne
The practical knowledge built up by doing a particular job in a particular place cannot be written down as a procedure, and is lost when the procedure replaces it.
Policy resistance
A system pushed towards one actor’s goal pushes back, because everyone else acting on it works harder to restore the position they wanted.
Jevons paradox
Making the use of a resource more efficient can increase the total amount of it consumed, because efficiency makes the service it provides cheaper.
Braess’s paradox
Adding a road to a network in which drivers choose their own routes can make every driver slower.
Downs–Thomson paradox
Where travellers can switch between driving and public transport, road speeds settle at the speed of the alternative, so widening the road can leave everyone slower.
Induced demand
New road capacity is filled by traffic that did not exist before it was built, so congestion returns to close to where it started.
Solutionism
The habit of recasting a complex, contested situation as a neat problem that happens to fit the tools already to hand.
Technocentrism
The habit of asking what a technology does to people, as though the technology acted alone and the arrangements around it were incidental.
The archetypes, as mechanisms
A system with a delay, a feedback loop and a limit will defeat a plan that has none of them.
Fixes that fail
A remedy that relieves the symptom quickly sets in motion a slower consequence that returns the symptom, larger.
Shifting the burden
A symptomatic remedy relieves the problem well enough that the fundamental capability is never built, and then cannot be.
Limits to growth
A reinforcing engine of growth eventually meets a constraint, and pushing the engine harder does nothing but raise the cost of hitting it.
Success to the successful
Two parties draw on one pool of resource, and an early advantage to either is converted into the resources that produce the next advantage.
Eroding goals
When performance falls short, the gap can be closed by lowering the goal, and a goal that is allowed to move will move.
Escalation
Two parties each act to restore their position relative to the other, so every move provokes the counter-move that makes it necessary again.
Accidental adversaries
Two parties who gain from cooperating each take a local action that solves their own problem by obstructing the other, and the partnership decays without anyone intending it.
Growth and underinvestment
Growth loads capacity, service quality falls, demand falls with it, and the fall in demand is read as evidence that the capacity was never needed.
Sub-optimisation
Optimising each part of a system on its own measure degrades the whole, because the parts are coupled and their local optima conflict.
The moving bottleneck
Relieving the constraint in a flow system does not remove the constraint; it moves to the next resource, and effort spent anywhere else adds cost without adding throughput.
The utilisation trap
As a resource is loaded towards full capacity, waiting time rises without limit, so the last few percentage points of utilisation cost far more than they return.
Bullwhip effect
Variation in end demand is amplified at each step back up a supply chain, so the stage furthest upstream sees swings many times larger than anything the customer did.
Delay-induced oscillation
A correcting loop that acts on delayed information will overshoot, and if it corrects hard enough relative to the delay the overshoot grows into a standing cycle.
Why the business case is never the outcome
The evidence on large projects is unusually good, unusually consistent and unusually ignored.
The iron law of megaprojects
Large projects come in over budget, over time and under benefit, at a rate that has not improved across the decades for which records exist.
Strategic misrepresentation
Forecasts attached to a proposal are shaped by what will win approval, so the numbers that reach the decision are optimistic by design rather than by accident.
Reference-class forecasting
Forecast a project from the outturn distribution of similar completed projects rather than from an estimate assembled out of its own details.
The optimism bias uplift
Add a mandated percentage to a project’s own cost estimate at approval, set from the outturn of past projects of the same type, and reduce it only as specific risks are actually retired.
The ninety-ninety rule
The first 90 per cent of a project takes 90 per cent of the time, and the remaining 10 per cent takes the other 90 per cent.
Student syndrome
Work that is given a padded deadline is started at the last moment the deadline allows, so the padding is spent before the work begins.
Buffer erosion
Safety time held inside individual task estimates is consumed rather than pooled, so a project can run out of protection long before it runs out of work.
Scope creep
Deliverables grow by increments small enough that none triggers a re-plan, until the total is unrecognisable and the date has not moved.
Requirement churn
Requirements that keep changing after design has begun impose rework whose cost rises with everything already built on the version being replaced.
The pilot paradox
A pilot succeeds on conditions a rollout cannot reproduce, so the better it is run the less its result tells you.
Hawthorne effect
Behaviour is said to change because it is being observed — a claim named after a study whose own data do not support it.
The pilot-to-scale gap
Effects measured in small trials run by the people who designed a programme shrink, often to nothing, when it is evaluated independently at scale.
Initiative fatigue
Initiatives are added faster than they are retired, so each receives too small a share of attention to change anything.
The J-curve of change
Performance falls before it rises after a change, because the supports for the old practice go before the new practice is competent.
The change curve
The five stages of grief, borrowed as a schedule for how staff will react to organisational change, despite failing as a description of grief itself.
The benefits realisation gap
The outputs of a project are delivered while the benefits promised in its business case are never measured, never realised, or quietly redefined.
The failure
How things break, what changes when the decision is delegated, and the story told afterwards.
How systems break
Disasters are rarely one failure. They are a long accumulation of small accepted deviations, meeting one bad day.
Normalisation of deviance
A group repeatedly accepts a departure from its own standard without harm, and the departure becomes the standard against which the next one is judged.
The Swiss cheese model
An accident requires a momentary alignment of holes in several successive layers of defence, so the useful question is why the defences were weak rather than who made the final error.
Normal accidents
In systems that are both interactively complex and tightly coupled, serious accidents are a property of the design rather than a failure of the operators, and cannot be engineered away by adding more safety devices.
Common-mode failure
Redundant components that share a cause fail together, so a reliability figure obtained by multiplying independent failure probabilities can be wrong by orders of magnitude.
Cascading failure
When the load carried by a failed element is redistributed to its neighbours, each with a finite margin, a single local failure can propagate until it takes down a system far larger than itself.
Monoculture fragility
A population of near-identical units is efficient and uniformly vulnerable: one pathogen, exploit or design flaw matched to the shared type takes all of it at once.
The efficiency–thoroughness trade-off
People and organisations continually trade thoroughness for efficiency, and because the trade almost always works, the adjustment that normally produces success is the same one that occasionally produces the failure.
Safety-I and Safety-II
Safety can be defined as the absence of accidents, which directs attention to the rare cases that go wrong, or as the capacity to succeed under varying conditions, which directs attention to the ordinary work that goes right.
High-reliability organisations
A few organisations operate hazardous technologies with far fewer accidents than their risk profile predicts, and the explanation offered is a set of organising practices rather than better technology.
Near-miss discounting
An event that could have caused harm but did not is filed as evidence that the system works, rather than as evidence that it nearly failed.
Broken windows
Visible small disorder, left unrepaired, is held to signal that nobody is watching, and so to invite larger disorder.
The ageing safety case
A safety argument is true of the system as it was when the argument was written, and quietly becomes false as the system, its staff and its demands change around it.
When the decision is handed over
Automation does not remove the human from the loop. It changes what the human is left doing, usually for the worse.
Ironies of automation
Automating the easy parts of a job leaves the operator the hard parts, less practice at them, and the duty of taking over exactly when things are worst.
Automation complacency
Operators monitoring a highly reliable automated system check it less and less, and so miss the rare occasion when it is wrong.
Out-of-the-loop performance
An operator who has not been doing the task loses the picture of its current state, and so recovers slowly and badly when handed control.
Automation surprise
The machine does something the operator did not expect, and the operator cannot work out what it is doing, or why, in the time available.
The moral crumple zone
When a largely automated system fails, responsibility concentrates on the nearest human operator, who had neither the control nor the information to prevent it.
Algorithm aversion
People abandon a statistical forecast after seeing it err, even when it is still more accurate than the human judgement they return to.
Algorithm appreciation
Lay judges often weight advice more heavily when it is labelled as coming from an algorithm than from a person, but the preference reverses by task and fades among experts.
The accountability gap
An automated decision passes through so many hands that no one of them can be held answerable for its outcome, and the system itself cannot be.
Deskilling
Work is reorganised so that the knowledge needed to do it moves out of the worker and into procedures, machines or management, leaving a narrower job behind.
The review, and what it gets wrong
The investigation is where an organisation decides what happened, and it is subject to its own failure modes.
The root-cause fallacy
An accident in a complex system has no single root cause, only a set of conditions that had to coincide, so a search for one will always find something and always stop too early.
Local rationality
People do what makes sense given their goals, their knowledge and their focus of attention at the moment, so an action that looks irrational afterwards was reasonable from inside.
Hindsight in incident review
Once reviewers know how an episode ended, they cannot recover how uncertain it looked beforehand, and the outcome makes the warning signs seem obvious and the decision negligent.
The human error label
Calling an outcome human error names the last person in the chain and ends the inquiry, turning the thing that needs explaining into the explanation.
Just culture
A reporting system works only when staff know in advance where the line falls between an honest mistake, which will be treated as information, and a reckless act, which will not.
The halo effect in business research
Knowing that a company performed well leads observers to rate its culture, leadership and strategy highly, so studies asking what made great companies great are measuring the result rather than the cause.
Survivorship in best practice
Guidance drawn only from organisations that succeeded cannot say which of their practices mattered, because the ones that did the same things and failed were never in the sample.
Regression in company performance
Exceptional company performance is part signal and part luck, so extreme results move back towards the average whatever anyone does, and the practices credited for the peak are blamed for the fall.
The curse of the business book
Companies selected as exemplars by a bestselling management book tend to fall back towards the average soon after publication, leaving the principles drawn from them unsupported.
The people
Belief that becomes fact, who rises and on what, and power at its harder end.
Belief that becomes fact
A belief about a group can make itself true, and a belief about what others believe can move faster than either.
Self-fulfilling prophecy
A definition of a situation that is false to begin with calls out behaviour that makes it true, and the outcome is then read as proof that the definition was right all along.
The Thomas theorem
If people define situations as real, they are real in their consequences, whatever the situation actually is.
Pygmalion effect
Teachers told that particular pupils were about to bloom were reported to raise those pupils’ measured ability, an effect the later evidence has cut down sharply.
Golem effect
Low expectations held by a teacher or a supervisor are said to depress the performance of the people they are held about, the mirror image of the Pygmalion claim.
Labelling theory
An official label applied to a person changes how others treat them and how they come to see themselves, and can produce more of the behaviour it names.
Stereotype threat
People at risk of confirming a negative stereotype about their group are held to perform worse on tests when that stereotype is made salient.
Matthew effect
Advantage compounds: an early lead in resources, credit or recognition attracts more of the same, so small initial differences widen into large ones.
Descriptive and injunctive norms
What most people actually do and what most people approve of are two different norms, and a message that confuses them can push behaviour the wrong way.
The boomerang effect in norm messaging
Telling people how they compare with the average moves those already better than average in the wrong direction, unless the message also says which direction is approved.
Social proof
People take what others around them are doing as evidence of what is correct, so a practice can spread through an organisation on the strength of its adoption count alone.
Information cascade
When people act in sequence and can see each other’s choices but not their reasons, it becomes rational to ignore your own information, and the group converges on a position resting on the first few signals.
Availability cascade
A risk gains public credibility through repetition rather than measurement, because each retelling makes it easier to recall and makes doubt more costly to voice.
Purity spiral
Where status comes from demonstrating commitment and nobody gains by arguing for less, the standard ratchets upward until ordinary members are disqualified by a standard they helped to set.
The Overton window
At any moment only a band of policy options can be advocated by someone who wants to stay in office, and what changes a policy is usually the movement of that band rather than an argument about the option.
Who rises, and on what
Appraisal, promotion and hiring are measurement problems, and they fail in the ways measurement fails.
Halo and horns in appraisal
An overall impression of a person colours every separate judgement made about them, so ratings of distinct qualities move together and carry far less information than their number suggests.
Recency in performance review
Reviews are widely believed to weight the final weeks of the period far above the rest; the appraisal evidence finds that the standing impression does most of the work and that the direction of the timing effect is not fixed.
Leniency, severity and central tendency
Raters differ systematically in where they place people on a scale, some high, some low, some all in the middle, so a rating carries information about the rater as well as about the person rated.
The similar-to-me effect
Raters judge people they perceive as similar to themselves more favourably, and the similarity that does the work is one of attitude and outlook rather than of demography.
Homophily and culture fit
Ties form between similar people far more often than chance allows, so a pipeline built on referral reproduces its own composition, and a criterion called fit turns that pattern into a rule.
The glass ceiling
Women and minority staff move normally through the lower and middle grades and then meet a barrier at senior level that their qualifications, tenure and performance do not explain.
The glass cliff
Women and minority candidates are appointed more often to leadership posts that are already in trouble, so their tenure starts with a raised chance of visible failure.
The queen bee phenomenon
Women who have reached senior posts in a male-dominated organisation distance themselves from junior women and judge them more harshly than their male colleagues do.
Tokenism
Where a group contains only a few members of a visibly different category, those few are treated as representatives of the category rather than as individuals.
The sponsorship gap
Women and minority staff receive advice and encouragement as often as their peers but are less often advocated for by someone with the standing to allocate a post.
Credential inflation
As a qualification becomes more common, the level demanded for a given job rises, so more education buys the same position.
Up-or-out
An organisation promotes from within on a fixed clock and requires anyone not promoted by the deadline to leave.
The harder end
The smallest family, and the one where the cost falls on a person rather than on a budget.
Abusive supervision
Subordinates perceive a sustained pattern of hostile verbal and non-verbal conduct from their supervisor, excluding physical contact.
Trickle-down hostility
Hostile treatment a manager receives from their own superior is passed down the hierarchy, so conduct at the top of an organisation reappears at the bottom.
Petty tyranny
A manager uses the authority of a small post to control and belittle subordinates in ways that serve the manager rather than the work.
Mobbing
One person is singled out for sustained hostile acts by a group of colleagues, so that the harm comes from the pattern and its duration rather than from any single act.
The toxic handler
Someone absorbs and neutralises the anger, anxiety and disappointment that decisions elsewhere in the organisation generate, at a cost that appears in no account and no job description.
Dark-triad leadership
The claim that narcissism, Machiavellianism and psychopathy are concentrated at the top of organisations and account for much of the harm done there, which the measured literature supports far more weakly than the claim is made.
Court politics
Where one person holds wide discretion, the organisation reorganises itself around access to that person, and proximity becomes the currency the formal structure no longer describes.
Managing up as displacement
Effort spent shaping how a manager sees the work is rewarded about as well as the work itself, so substituting the first for the second is a rational response to how appraisal is built.
The empty-chair problem
The people a decision is about are absent when it is made, so the standing remedy is to seat them, or someone who is accountable to them and can lose the argument on their behalf.
The crowd and the operator
The same mechanisms past the walls of any one organisation, and the same mechanisms operated deliberately.
When it spreads beyond the organisation
The same mechanisms at the scale of a town, a profession or a country, where the correction arrives late or not at all.
Mass psychogenic illness
Physical symptoms spread through a group by observation and expectation rather than by any organic agent, most often in closed settings such as schools and factories.
Moral panic
A group or condition is defined as a threat to shared values and the reaction runs ahead of any measured harm, leaving behind institutional changes that outlast the episode.
Deviancy amplification
The reaction to a behaviour increases the behaviour, because the response isolates the people labelled and makes the label the most available identity they have.
Speculative mania
A credit-fed price rise in which the reason to buy is that others are buying, running through a standard sequence to a point at which everyone tries to sell at once.
Tulip mania
The Dutch bulb trade of 1636–37 is the standard illustration of mass financial madness, and most of the detail usually given for it was invented two centuries afterwards.
Witch-hunt dynamics
An accusation system in which denial counts as evidence of guilt and confession buys leniency in exchange for naming others will grow until an authority changes the rules of evidence.
Rumour transmission
A rumour is not a message decaying as it passes down a chain but a group building an explanation for something it needs explained, and its accuracy depends on whether the network contains anyone who can check it.
The urban legend
A story told as true, set locally and sourced to a friend of a friend, which persists because the versions that provoke disgust or fear are passed on more often than the versions that are accurate.
The recovered-memory panic
Therapeutic techniques adopted from the late 1980s to recover repressed memories of abuse are the same procedures that in the laboratory reliably generate confident memories of events that did not occur.
The satanic panic
A circulating legend of organised ritual abuse acquired investigative and therapeutic machinery that produced the accounts it was looking for, and no verified instance was ever found.
Conspiracy cascade
A belief spreads through a closed network by cascade and then seals itself, because the evidence that would refute it is issued by the sources the belief has already disqualified.
Millenarian disconfirmation
The claim that believers respond to a publicly failed prophecy by proselytising harder rests on one contaminated case study, and later surveys of failed prophecies find it is not the usual response.
Folie à deux
A delusion held by two people in a closed relationship, sustained less by transmission from one mind to the other than by the absence of anyone outside able to contradict it.
Crowd psychology
The idea that a crowd dissolves individual judgement into a primitive collective mind comes from Le Bon and has no evidential support; systematic study finds crowd action patterned and bounded by shared identity.
The mechanisms, operated on purpose
Everything in the first nineteen families can be run deliberately, and this family is how.
Astroturfing
A campaign funded and directed by an interested party is presented as spontaneous public opinion, so that a sponsor’s position appears to be a constituency’s.
Manufacturing consent
A propaganda model in which five structural filters, rather than censorship, make a commercial press system produce coverage broadly aligned with the interests of those who fund and source it.
Agenda setting
Media coverage transfers salience rather than opinion: the issues given most attention become the issues the public names as most important.
The firehose of falsehood
A propaganda pattern defined by high volume across many channels, rapid repetition, and no commitment either to accuracy or to consistency between its own claims.
Fear, uncertainty and doubt
An incumbent defends its position not by making a case but by raising doubts that make any change look risky, so that the safe course is to do nothing.
Dark patterns
Interfaces built so that the choice favouring the operator is easy and the choice favouring the user is effortful, hidden or embarrassing.
Foot in the door
Agreeing to a small request raises the chance of agreeing to a much larger one later, because the first compliance changes how the person describes themselves.
Door in the face
A request large enough to be refused makes a smaller follow-up more likely to be granted, because the retreat reads as a concession that ought to be reciprocated.
Manufactured scarcity
Availability is restricted, or made to appear restricted, so that the thing is valued more highly and decided on more quickly.
Gaslighting
A sustained attempt to make a person distrust their own perception and memory, so that their account of events can be discounted — by others, and eventually by themselves.
DARVO
A person or body answering an accusation denies the conduct, attacks the credibility of whoever raised it, and reverses the roles so that the accused appears as the injured party and the accuser as the aggressor.
Whataboutism
A charge is met not with a defence but with a counter-charge about the accuser or their side, so the question of what happened is replaced by a comparison of records.
Motte and bailey
An ambitious claim that could not survive challenge is advanced under cover of a modest one that can, with the arguer retreating to the modest claim when pressed and returning to the ambitious one when not.
Seven hundred and five works
Every entry names what it rests on, and the reference list holds all of them. Where an entry rests on nothing citable, it says so instead.
Every entry in this guide is indexed, with its definition, at https://www.geraldajam.com/library/glossary/field-guides/collective-fallacies.