Mental Health

Mandy Kloppers

How to Use Occam’s Razor

Occam’s razor is one of the most useful, (yet misunderstood,) models in your mental toolbox to solve problems more quickly and efficiently. Here’s how to use it.


Occam’s razor (also known as the “law of parsimony”) is a problem-solving principle which serves as a useful mental model. A philosophical razor is a tool used to eliminate improbable options in a given situation. Occam’s is the best-known example.

Occam’s razor can be summarized as follows:

Among competing hypotheses, the one with the fewest assumptions should be selected.

The Basics

In simpler language, Occam’s razor states that the simplest explanation is preferable to one that is more complex. Simple theories are easier to verify. Simple solutions are easier to execute.

In other words, we should avoid looking for excessively complex solutions to a problem, and focus on what works given the circumstances. Occam’s razor can be used in a wide range of situations, as a means of making rapid decisions and establishing truths without empirical evidence. It works best as a mental model for making initial conclusions before the full scope of information can be obtained.

If a person repeats the same action on a regular basis in response to the same cue and reward, it will become a habit as the corresponding neural pathway is formed. From then on, their brain will use less energy to complete the same action.

Scientists choose to opt for the simplest solution as the current data permits, while remaining open to the possibility of future research allowing for greater complexity.

The version used by scientists can best be summarized as:

When you have two competing theories that make exactly the same predictions, the simpler one is better.

Albert Einstein

Albert Einstein referred to Occam’s razor when developing his theory of special relativity. He formulated his own version: “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.” Or, “Everything should be made as simple as possible, but not simpler.”


Modern doctors use a version of Occam’s razor, stating that they should look for the fewest possible causes to explain their patient’s multiple symptoms, and give preference to the most likely causes. A doctor we know often repeats the aphorism that “common things are common.” Interns are instructed, “when you hear hoofbeats, think horses, not zebras.” For example, a person displaying influenza-like symptoms during an epidemic would be considered more likely to be suffering from influenza than an alternative, rarer disease. Making minimal diagnoses reduces the risk of over-treating a patient, causing panic, or causing dangerous interactions between different treatments. This is of particular importance within the current medical model, where patients are likely to see numerous health specialists and communication between them can be poor.

Prison Abolition and Fair Punishment

Punishments should not cause more pain than they prevent. Life imprisonment for murder could be seen as justified in that it might prevent a great deal of potential pain, should the perpetrator offend again. On the other hand, long-term imprisonment of an impoverished person for stealing food causes substantial suffering without preventing any.

Exceptions and Issues

It is important to note that, like any mental model, Occam’s razor is not foolproof. Use it with care, lest you cut yourself. This is especially crucial when it comes to important or risky decisions. There are exceptions to any rule, and we should never blindly follow the results of applying a mental model which logic, experience, or empirical evidence contradict. When you hear hoofbeats behind you, in most cases you should think horses, not zebras—unless you are out on the African savannah.

Photo by Lisette Verwoerd on Unsplash