Using Occam's razor to choose the simplest explanation.

Slice through complexity and sharpen up with Occam’s razor

If you ask the general public about science, you might hear that science is concerned with complex outcomes, preferring these over simplicity. But, although science is often complex, the outcomes, hypotheses, or ideas don’t necessarily need complexity. In fact, the parsimony principle constitutes one of the pillars of a scientific mindset: Occam’s razor. Used thoughtfully and responsibly, Occam’s razor can simplify the choice between several explanations and hypotheses.

Occam’s razor is a philosophical principle named after William of Ockham, a Franciscan friar who made notable contributions to logic, physics, and theology during his time at Oxford during the 14th century. While the idea is not unique to William of Ockham – since several philosophers used it before him, including Plato – William of Ockham did popularize Occam’s razor.

Ockham’s ideas resonated with his contemporary scholars, and his pursuit of simplicity left a lasting mark, specifically in science. Over time, Occam’s razor became associated with his name as a tribute to his contributions, and it continues to influence critical thinking and problem-solving today.

William of Ockham, who popularized Occam's razor.
William of Ockham. Av Moscarlop. Lisens: CC BY SA 3.0

The principle suggests that in the pursuit of truth, “Entities are not to be multiplied beyond necessity,” or in simpler terms, “The simplest explanation is often the best one.”

However, Occam’s razor is often misunderstood. People sometimes oversimplify it with catchy sayings like “Keep it simple, stupid” or “Choose the simplest solution when in doubt.” Instead, its real purpose is to reject overly complicated explanations that are less likely to be correct.

You’ve probably heard the expression, “If you hear hoofbeats, think horses, not zebras.” Medical students learn this concept early on during their studies to reflect on how, for example, a patient with flu-like symptoms probably caught the flu rather than another obscure flu-like disease. In other words, the simplest explanation with the fewest number of entities and unproven or previously unknown assumptions probably serves as an explanation.

Understanding Occam’s razor through your reality

One way of depicting Occam’s razor is by imagining a mental list of everything you know and your beliefs. Everything you encounter and reflect upon in this world makes it to the list. The list probably contains bottles, trees, clouds, birthmarks, germs, etc.

Now imagine sitting by the window one day and suddenly asking yourself, “Why does it rain?” Let’s say you come up with two explanations: one involving trolls peeing down on you from the clouds and another involving water-comprising clouds that can’t contain their heavy water drops. 

According to Occam’s razor, you should choose the latter (cloud-related) assumption over the former (troll-related) explanation. Why? Because clouds and their properties already exist in your mental list of beliefs – you’ve either seen them or learned about them somehow. By contrast, trolls don’t comprise the list of beliefs, and you’d struggle to explain where they’re from, how they ended up on the fluffy clouds, how the trolls manage to stand on these fluffy clouds, and so on. Occam’s razor would suggest discarding the troll explanation in favor of the cloud explanation since the former requires more new, unknown, and unproven ideas.

When can you implement Occam’s razor?

You might be asking yourself about the significance of the concept in your reality and your interest in improving critical thinking and problem-solving skills. After all, you don’t believe in trolls, and although the peeing example brought a well-earned smile, you already know the properties of rain and clouds. So what’s the point?

A more realistic scenario would be one where you try to solve problems at work or in your everyday life.

Another big one is the consumption of information. As noted in a previous post on conflicts of interest, biases and hidden agendas are widespread. An analytical mind has to ask the right questions to identify the most logical explanations. For example, you can start asking yourself if the information you consume requires overly complex ideas or explanations to hold up. Give it a shot and analyze arguments concerning the coronavirus origins, religion, vaccine theories, election fraud, or polarizing geopolitical topics, to name a few, with Ockham in mind. Ask yourself: what are the available arguments? And which of these require the most straightforward and known assumptions?

However, as we’ll see, you must do some work before confirming your choice. But first, let’s play a game.

Quick quiz: What would Occam’s razor suggest?

Below, you’ll find five cases representing standard work or study scenarios with two possible explanations that may pop up. Your task is to find the explanation that Occam’s razor would likely suggest as the most likely explanation. Read the five examples, write down your answers, and reveal the correct answer – according to Occam’s razor – once you’re done with this article. Let’s start!

Case 1. Office IT Problem:

Your computer is suddenly freezing and crashing frequently.


Explanation 1: A complex and rare virus has infected your computer.

Explanation 2: The computer’s hardware is overheating due to dust buildup.

Case 2. University Research Findings:

You’ve conducted a study, and the results show a significant but unexpected correlation between two variables.


Explanation 1: The variables have a hidden, complex causal relationship.

Explanation 2: The correlation is a statistical anomaly or due to random chance.

Case 3. Office Project Delays:

A project at work is consistently missing deadlines.


Explanation 1: The team is not managing their time effectively, and there are internal coordination issues.

Explanation 2: An external and highly unusual factor, such as unforeseeable market fluctuations, is causing the delays.

Case 4. Classroom Test Results:

Some students perform exceptionally well on a test in a university course while others struggle.


Explanation 1: The high-performing students are exceptionally talented, while the struggling students are not.

Explanation 2: The test questions were ambiguous or poorly designed, leading to variable results.

Case 5. Lab Experiment Inconsistencies:

In a scientific experiment, you observe inconsistent results despite controlling all variables.


Explanation 1: There is a yet-undiscovered natural phenomenon causing the inconsistencies.

Explanation 2: Human error during data collection or equipment calibration caused the discrepancies.

Criticisms of Occam’s razor

Before embracing Occam’s razor wholeheartedly for solving problems, remember it’s not an absolute rule. It’s a rule of thumb, a heuristic that encourages us to favor the simplest explanations over complex ones to reach the truth. So, it doesn’t relieve you from critical thinking altogether.

Blindly adhering to Occam’s razor can make you overlook more complex or nuanced explanations that may align better with the intricacies of reality. Although simplicity can help you identify the most plausible explanations, you should apply Occam’s razor carefully, assessing individual problems carefully and thoughtfully. Each situation requires careful consideration of the specific problem and the available evidence. So, while you don’t want to seek overly complex explanations, complexity can have value depending on the situation.  

In other words, you want to gather as much information as possible before eliminating possible options. Looking at two or three options and choosing between these while neglecting other viable ones isn’t scientific. Still, it’s an all too common practice in a fast-paced, debate-styled information landscape in which we barely have time to dig into the available information.  Instead, using Occam’s razor requires considering the most essential explanations available.

Divine creation over evolution

Although you may criticize Occam’s razor – and many experts do – it sometimes gets a bad rep for the wrong reasons.

For example, some would claim that religion and a divine creation would be simpler than evolution from common ancestors. Before Charles Darwin proposed the evolution theory, his grandfather, Erasmus Darwin, proposed a similar theory. However, Erasmus’s proposal had to compete with the presumably more straightforward “divine creation” explanation. So what’s going on here? According to this perspective, the counterargument to Occam’s razor may state that “a supernatural creator might seem like a pretty complex assumption today, but it wouldn’t have looked that way in the devout Victorian age.” You can find the article here.

Using Occam's razor to criticize divine creation.
Image by Sabine Zierer from Pixabay

However, the criticism encounters two main problems – in my humble opinion. Firstly, like cloud trolls peeing rain on your head, divine creation would require too many unknowns and unproven beliefs. An honest derivation of the divine creation requires you to confirm several unknowns, such as the creation and location of God, the creation timeframe, and traces of these. Ultimately, the explanation requires more complexity than is immediately apparent.

Secondly, and this point addresses the argument more specifically, you should see Occam’s razor as a context-dependent (temporal) procedure. The comparison between Erasmus’s theory and the prevailing views of divine creationism in the “devout Victorian age” may not be a fair scientific comparison. Historical context, prevailing beliefs, and the level of scientific understanding play a significant role in evaluating the complexity of theories. Several factors, beyond simplicity, influence the scientific community’s acceptance of an idea. Like it or not, scientists adhere to societal beliefs – sometimes dogmatic – apart from evidence and the ability of an explanation to effectively account for multiple observed phenomena, known as explanatory power.

The criticism argues based on dogmas and norms during the Victorian age and the resulting scientific decisions. The factual scientific evidence for evolution hides in the background of the decision-making and societal norms at that time. So, in this case, the criticism portrays an unfair picture of Occam’s razor since societal decisions don’t define scientifically sound discussions.

Francis Crick cautions against the use of Occam’s razor in biology

Francis Crick once stated, “While Occam’s razor is a useful tool in the physical sciences, it can be a very dangerous implement in biology. It is thus very rash to use simplicity and elegance as a guide in biological research.”

We can assume that Francis Crick, one of the leading researchers defining the structure of DNA, refers to the overuse of Occam’s razor in biology. The quote suggests that the complexity of biological mechanisms (sometimes) requires complex explanations. When argued in the context of overuse, the criticism holds since exaggerated reliance on simplicity can misrepresent reality.

However, biology is not necessarily immune to the use of Occam’s razor but, once again, a matter of context. Specifically, explanations we have accepted today may seem complex after the fact. However, the final, complex “full picture” doesn’t define the scientific processes and discussions to get there. Reaching our complete understanding of biological knowledge required several stages of collecting data in which scientists applied Occam’s razor (or not). The biological findings we see today – after the fact – are more complete and seem more complex, but the path there might have required simple explanations over more complex ones.

Simply speaking, Occam’s razor resembles Snapchat Stories. It’s valuable when capturing the moment but loses relevance as time passes and new things are discovered. Hypotheses keep changing the more we learn, and, as a result, so does the complexity of our understanding. In other words, investigate the problem and its explanations thoroughly and make quality decisions based on the existing data while keeping it simple – and use it with care. I hope that makes sense.

Results: The game

Case 1. Office IT problem:

Choice based on Occam’s razor:

Occam’s Razor suggests choosing Explanation 2 – the hardware overheating due to dust buildup – because it involves fewer assumptions (no need to assume a rare virus) and is a more straightforward, more common issue.

Case 2. University research findings:

Choice based on Occam’s razor:

Occam’s Razor suggests choosing Explanation 2 – that the correlation is a statistical anomaly – because it doesn’t require introducing a complex, hidden causal relationship that lacks empirical evidence.

Case 3. Office project delays:

Choice based on Occam’s razor:

Occam’s Razor suggests choosing Explanation 1 – internal coordination issues – because it involves fewer assumptions and is a more common problem in project management.

Case 4. Classroom test results:

Choice based on Occam’s razor:

Occam’s Razor suggests choosing Explanation 2 – poorly designed test questions – because it doesn’t require assuming innate talent differences and is a simpler explanation for variable test results.

Case 5. Lab experiment inconsistencies:

Choice based on Occam’s razor:

Occam’s Razor suggests choosing Explanation 2 – human error – because it involves fewer assumptions and is a more common cause of inconsistencies in controlled experiments.

How many correct answers did you get?

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