What is Hickam’s Dictum?

Hickam’s dictum is the counterargument to Occam’s razor. Whereas Occam’s razor is a heuristic that tends to narrow down decision-making to the simplest variables, Hickam’s dictum believes a situation must be tackled by looking at multiple variables.

Understanding the Hickam’s dictum

Occam’s razor is used in the medical industry to imply that multiple symptoms in a patient can be attributed to a single disease.

Hickam’s dictum counters this argument, believing the patient’s multiple symptoms to be, in most cases, the result of several diseases.

Hickam’s dictum is based on an aphorism usually stated as “patients can have as many diseases as they damn well please.

This line is attributed to John Hickam, an American physician who worked at Grady Memorial Hospital in Atlanta in his early career and then became chairman of medicine at Indiana University between 1958 and 1970.

Hickham’s dictum and diagnostic parsimony

In contemporary medicine, Occam’s razor is often discussed by doctors in the context of diagnostic parsimony.

This principle advocates that doctors look for the fewest possible causes to account for all symptoms when diagnosing an injury, illness, or disease. 

This approach has limited use in modern medical practice, however, with the actual process of patient diagnosis consisting of multiple hypotheses that must be tested and modified as necessary.

Hickam’s dictum asserts that as doctors carry out this process, no potential diagnosis should be excluded on the basis that it does not appear to satisfy the principle of Occam’s razor. 

Note that Occam’s razor does not require that the doctor necessarily choose the simplest diagnosis.

Instead, it encourages the practitioner to find an explanation that accounts for all evidence without making undue assumptions.

With the above in mind, Occam’s razor can be a useful diagnostic tool – but it is by no means infallible. In medicine, the simplest answer – or the one with the fewest number of diagnoses – is not always the correct answer. 

Hickam’s dictum and statistical analysis

That Hickam’s dictum can serve as a counterargument to Occam’s razor is down to statistical analysis.

Stats show that patients are more likely to have multiple diseases and less likely to have one, rarer disease that accounts for all their symptoms. 

Some patients with multiple diseases may also receive a diagnosis that each disease has an independent cause rather than all diseases being attributable to a single source.

That is, each disease is derived from separate events (or a combination of events) to which the patient has been exposed. 

When doctors diagnose a patient with one rare disease, they make a critical assumption that is often unrelated to the patient’s symptoms and is statistically unlikely in any case.

Conversely, when the patient is diagnosed with three common conditions to which they may already be predisposed, the doctor minimizes the introduction of new assumptions that can lead to an incorrect diagnosis.

Hickam’s dictum in business

As the volume, variety, and velocity of modern datasets increases, the probability that a business will encounter Hickam’s dictum increases in turn.

Data can now be combined to diagnose and solve problems in a way that was once unimaginable, so the relative simplicity of Occam’s razor may be less useful in some instances.

With that said, most businesses will benefit from a combination of advanced data analytics (Hickam’s dictum) and Occam’s razor where they default to the simplest explanation possible.


Take McDonald’s, for example, where almost every process has been recorded and standardized to increase efficiency and profits.

In fact, the company is a master of solving problems with simple solutions and then turning them into systems. 

Many restaurants contend with the problem of sourcing trained cooks and chefs, but McDonald’s solves this issue with simple menu items that can be quickly and easily prepared by anyone.

Indeed, the company could take a high school student off the street with zero experience and teach them to prepare a Big Mac in a matter of days. 

There are also systems in place to ensure the food is made to a consistent standard, such as those that dictate the correct temperature of the fryer.

The bathrooms in McDonald’s restaurants are also clean and functional and its systemized employee training program is respected around the world.

McDonald’s and data

While McDonald’s is a systemized company, it is not afraid to make decisions and solve problems based on data collected from its vast network of restaurants. Based on this data, for example, the company identified three areas of improvement:

  1. The design of the drive-thru itself.
  2. The information provided to customers in the drive-thru, and
  3. The nature of the people waiting in line to order. 

By analyzing the data, McDonald’s was able to determine what times of day customers were most likely to visit and add extra staff to reduce wait times.

But it has also introduced AI that analyzes local buying patterns based on factors such as events, celebrations, weekends, or even whether it is payday for employees in the area.

Based on these patterns, the AI recommends relevant food and drink suggestions on the drive-thru screen for that specific restaurant and time of day.

The point is there that to improve its drive-thru experience, McDonald’s did not default to the simplest or most likely solution (reducing wait times).

Instead, by analyzing data from its restaurants, the company determined that its inadequate drive-thru experience could be explained by multiple, less-common “diagnoses” that may have otherwise been overlooked.

Key takeaways:

  • Hickam’s dictum, used in the medical industry as a counterargument to Occam’s razor, believes multiple symptoms can be attributed to one disease.
  • In contemporary medicine, Occam’s razor is often discussed by doctors in the context of diagnostic parsimony. This principle advocates that doctors look for the fewest possible causes to account for all symptoms when diagnosing an injury, illness, or disease. 
  • Hickam’s dictum is a counterargument to Occam’s razor because it is based on statistical evidence. Stats show that patients are more likely to have multiple diseases or comorbidities and less likely to have one, rarer disease that accounts for all their symptoms.

Connected Thinking Frameworks

Convergent vs. Divergent Thinking

Convergent thinking occurs when the solution to a problem can be found by applying established rules and logical reasoning. Whereas divergent thinking is an unstructured problem-solving method where participants are encouraged to develop many innovative ideas or solutions to a given problem. Where convergent thinking might work for larger, mature organizations where divergent thinking is more suited for startups and innovative companies.

Critical Thinking

Critical thinking involves analyzing observations, facts, evidence, and arguments to form a judgment about what someone reads, hears, says, or writes.

Systems Thinking

Systems thinking is a holistic means of investigating the factors and interactions that could contribute to a potential outcome. It is about thinking non-linearly, and understanding the second-order consequences of actions and input into the system.

Vertical Thinking

Vertical thinking, on the other hand, is a problem-solving approach that favors a selective, analytical, structured, and sequential mindset. The focus of vertical thinking is to arrive at a reasoned, defined solution.

Maslow’s Hammer

Maslow’s Hammer, otherwise known as the law of the instrument or the Einstellung effect, is a cognitive bias causing an over-reliance on a familiar tool. This can be expressed as the tendency to overuse a known tool (perhaps a hammer) to solve issues that might require a different tool. This problem is persistent in the business world where perhaps known tools or frameworks might be used in the wrong context (like business plans used as planning tools instead of only investors’ pitches).

Peter Principle

The Peter Principle was first described by Canadian sociologist Lawrence J. Peter in his 1969 book The Peter Principle. The Peter Principle states that people are continually promoted within an organization until they reach their level of incompetence.

Straw Man Fallacy

The straw man fallacy describes an argument that misrepresents an opponent’s stance to make rebuttal more convenient. The straw man fallacy is a type of informal logical fallacy, defined as a flaw in the structure of an argument that renders it invalid.

Streisand Effect

The Streisand Effect is a paradoxical phenomenon where the act of suppressing information to reduce visibility causes it to become more visible. In 2003, Streisand attempted to suppress aerial photographs of her Californian home by suing photographer Kenneth Adelman for an invasion of privacy. Adelman, who Streisand assumed was paparazzi, was instead taking photographs to document and study coastal erosion. In her quest for more privacy, Streisand’s efforts had the opposite effect.


As highlighted by German psychologist Gerd Gigerenzer in the paper “Heuristic Decision Making,” the term heuristic is of Greek origin, meaning “serving to find out or discover.” More precisely, a heuristic is a fast and accurate way to make decisions in the real world, which is driven by uncertainty.

Recognition Heuristic

The recognition heuristic is a psychological model of judgment and decision making. It is part of a suite of simple and economical heuristics proposed by psychologists Daniel Goldstein and Gerd Gigerenzer. The recognition heuristic argues that inferences are made about an object based on whether it is recognized or not.

Representativeness Heuristic

The representativeness heuristic was first described by psychologists Daniel Kahneman and Amos Tversky. The representativeness heuristic judges the probability of an event according to the degree to which that event resembles a broader class. When queried, most will choose the first option because the description of John matches the stereotype we may hold for an archaeologist.

Take-The-Best Heuristic

The take-the-best heuristic is a decision-making shortcut that helps an individual choose between several alternatives. The take-the-best (TTB) heuristic decides between two or more alternatives based on a single good attribute, otherwise known as a cue. In the process, less desirable attributes are ignored.


The concept of cognitive biases was introduced and popularized by the work of Amos Tversky and Daniel Kahneman in 1972. Biases are seen as systematic errors and flaws that make humans deviate from the standards of rationality, thus making us inept at making good decisions under uncertainty.

Bundling Bias

The bundling bias is a cognitive bias in e-commerce where a consumer tends not to use all of the products bought as a group, or bundle. Bundling occurs when individual products or services are sold together as a bundle. Common examples are tickets and experiences. The bundling bias dictates that consumers are less likely to use each item in the bundle. This means that the value of the bundle and indeed the value of each item in the bundle is decreased.

Barnum Effect

The Barnum Effect is a cognitive bias where individuals believe that generic information – which applies to most people – is specifically tailored for themselves.

First-Principles Thinking

First-principles thinking – sometimes called reasoning from first principles – is used to reverse-engineer complex problems and encourage creativity. It involves breaking down problems into basic elements and reassembling them from the ground up. Elon Musk is among the strongest proponents of this way of thinking.

Ladder Of Inference

The ladder of inference is a conscious or subconscious thinking process where an individual moves from a fact to a decision or action. The ladder of inference was created by academic Chris Argyris to illustrate how people form and then use mental models to make decisions.

Six Thinking Hats Model

The Six Thinking Hats model was created by psychologist Edward de Bono in 1986, who noted that personality type was a key driver of how people approached problem-solving. For example, optimists view situations differently from pessimists. Analytical individuals may generate ideas that a more emotional person would not, and vice versa.

Second-Order Thinking

Second-order thinking is a means of assessing the implications of our decisions by considering future consequences. Second-order thinking is a mental model that considers all future possibilities. It encourages individuals to think outside of the box so that they can prepare for every and eventuality. It also discourages the tendency for individuals to default to the most obvious choice.

Lateral Thinking

Lateral thinking is a business strategy that involves approaching a problem from a different direction. The strategy attempts to remove traditionally formulaic and routine approaches to problem-solving by advocating creative thinking, therefore finding unconventional ways to solve a known problem. This sort of non-linear approach to problem-solving, can at times, create a big impact.

Bounded Rationality

Bounded rationality is a concept attributed to Herbert Simon, an economist and political scientist interested in decision-making and how we make decisions in the real world. In fact, he believed that rather than optimizing (which was the mainstream view in the past decades) humans follow what he called satisficing.

Dunning-Kruger Effect

The Dunning-Kruger effect describes a cognitive bias where people with low ability in a task overestimate their ability to perform that task well. Consumers or businesses that do not possess the requisite knowledge make bad decisions. What’s more, knowledge gaps prevent the person or business from seeing their mistakes.

Occam’s Razor

Occam’s Razor states that one should not increase (beyond reason) the number of entities required to explain anything. All things being equal, the simplest solution is often the best one. The principle is attributed to 14th-century English theologian William of Ockham.

Mandela Effect

The Mandela effect is a phenomenon where a large group of people remembers an event differently from how it occurred. The Mandela effect was first described in relation to Fiona Broome, who believed that former South African President Nelson Mandela died in prison during the 1980s. While Mandela was released from prison in 1990 and died 23 years later, Broome remembered news coverage of his death in prison and even a speech from his widow. Of course, neither event occurred in reality. But Broome was later to discover that she was not the only one with the same recollection of events.

Crowding-Out Effect

The crowding-out effect occurs when public sector spending reduces spending in the private sector.

Bandwagon Effect

The bandwagon effect tells us that the more a belief or idea has been adopted by more people within a group, the more the individual adoption of that idea might increase within the same group. This is the psychological effect that leads to herd mentality. What in marketing can be associated with social proof.

Read Next: BiasesBounded RationalityMandela EffectDunning-Kruger EffectLindy EffectCrowding Out EffectBandwagon Effect.

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