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Occam's razor explained simply. The principle of parsimony from philosophy: Searching for the best explanation, find the simplest explanation!

Ockham's razor—a useful tool in logic

„Substantia non sunt multiplicanda praeter necessitatem.”

The principle of „Ockham's razor” is also known as the principle of parsimony (principle of economy). The term is derived from the name of William of Ockham, a brilliant theologian, philosopher, and logician of the Middle Ages. Its basic principle is still a guideline for logical thinking today. It states that of two competing theories that explain a phenomenon and both draw the same conclusion, are equally convincing, and both explain the problem satisfactorily, the logician should always choose the simpler solution. The solution with the fewest elements is most likely to be correct. (The idea is to cut out unnecessary parts, hence the name „razor.”)

An example will illustrate how „Ockham's razor” works:

Suppose you come home and find that your dog has escaped from its kennel and destroyed your couch. Two possible theories come to mind:

(1) You forgot to lock the kennel door, and the dog was able to open it. This is how the dog got free. This explanation requires two entities (you and the dog) and two actions (you forget to lock the kennel door, and the dog opens the door).

(2) A burglar managed to break open the front door, entered the house, and freed the dog from the kennel. He then sneaked away again and covered up all traces of his presence. Finally, he locked the front door again, trapping the dog inside, where it destroyed the couch. This theory requires three entities (you, the dog, and the burglar) and at least eight actions (breaking open the door, entering the house, freeing the dog, covering up the traces, locking the front door again, etc.). It also requires a plausible motive for the intruder, which is completely lacking at this point.

Either theory would be a reasonable and plausible explanation. Both explain the same phenomenon (the couch destroyed by the escaped dog), and both apply the same theory: that the kennel door was somehow opened (instead of a more far-fetched theory involving dog teleportation or aliens).

Which theory is most likely to be correct? If you find no evidence, such as fingerprints or footprints and missing possessions, to support theory No. 2, William of Ockham would say that the simpler solution (1) is most likely correct in this case. The first solution involves only two parts—two entities and two actions. On the other hand, the second theory requires at least eight parts—you, the dog, a hypothetical unknown intruder, a plausible motivation, and various actions. It is unnecessarily complex. „

Ockham's razor stated that the simpler theory is more likely to be correct than a theory that relies on many hypothetical additions to the evidence already gathered.

This is, of course, somewhat simplified, because the „substantia” of scholasticism did not simply have the meaning of elements. But the principle still holds true and also leads to the logically correct decision in our example.

Does that sound like a checkered cap, a pipe, a violin, and Dr. Watson to you? You're right: Sherlock Holmes, or rather his creator Arthur C. Doyle, used the principle incessantly without ever mentioning its real inventor by name. But we've made up for that now.

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https://www.praxis-psychologie-berlin.de/en/wikiblog-english/articles/belief-bias-ursachen-beispiele-und-vermeidung-des-denkfehlers

Occam's razor: Occam explained in philosophy

7 reasons why Occam's razor will become your new favourite tool

Think medieval monks are dry as dust? You thought wrong! William of Ockham left us a principle that will change the way you think forever. Before you delve into the depths of philosophy, here are seven smart facts about why you should immediately pack this „razor” in your toolbox.

1. It is the ultimate principle against complicated messes.

Imagine your mobile phone goes on strike. Do you explain it with a simple software error or with tiny aliens hijacking the memory? Occam's razor says, Start with the simplest solution! The explanation with the fewest additional assumptions is usually the best.

2. It shaves away nonsense—a kind of logical shaver.

The name says it all! The „razor” simply cuts away superfluous assumptions and complicated trains of thought. It is your tool for mental hygiene and shaves complex problems down to the essentials.

3. Everyone uses it—even without knowing the complicated name.

„Keep it simple, stupid!” (KISS principle), „Don't overthink it!” - All these modern sayings are basically the great-grandchildren of Occam's razor. You already know the instinct; now learn the name of the superhero behind it.

4. It's the secret star of shows like „House” or „Sherlock.”

„Whenever you have two possible explanations, take the simplest one first.” Detective series thrive on this. Dr. House would never think of an exotic rare disease first if the symptoms also fit a simple flu. Brilliant thinkers love simplicity.

5 It's your best friend in every decision.

Should you change jobs? Why didn't she answer? Instead of getting lost in confused speculation, ask yourself, what is the simplest explanation? Often the most obvious answer is also the most correct („She's just busy”) and saves you a lot of brooding.

6. Even Aristotle was bothered by this.

The whole argument was about „entities” (to put it simply: things that exist). Does „beauty” really exist, or are there only beautiful things? Ockham said, „Stop cluttering up your world with unnecessary things! There is only what we see.” Radically simple.

7. It will make you the smartest person in (almost) any discussion.

When someone comes around the corner with an ultra-complicated conspiracy theory, you simply ask, „Isn't that a bit… unnecessarily complicated?” You pull out Occam's razor, and bang—you throw an elegant principle into the ring that has survived for 700 years.

Got curious?

That was just the tip of the iceberg! Take a look at the article and find out what centuries-old dispute Ockham ended with his razor, why it doesn't mean that the simplest answer is always the right one, and how it even makes our algorithms better in modern computer science.

Introduction: Entia non sunt multiplicanda praeter necessitatem

The Latin phrase „Entia non sunt multiplicanda praeter necessitate” translates as „Entities should not be multiplied unnecessarily.” This phrase, often attributed to William of Ockham, summarises the essence of Occam’s razor: it is about making as few assumptions as possible in order to explain a situation. The use of Occam's razor helps to avoid unnecessary variables and hypotheses and thus to arrive at a clearer and more comprehensible theory.

What is the principle of parsimony?

The principle of parsimony, also known as parsimony, is at the heart of Occam's razor. It states that when explaining a phenomenon, we should choose the hypothesis that requires the fewest variables and assumptions. A simpler theory is then likely to be correct because it is less prone to error. William von Ockham emphasised that unnecessary entities should be avoided in order to arrive at a clear and efficient explanation.

Occam's Razor

The principle of simplicity is closely associated with the name of the philosopher William of Occam, although similar ideas existed before him. Occam's razor is a powerful tool in science and philosophy. It is used to select the most probable explanation from a set of competing explanations by favouring the explanation with the fewest assumptions. At its core, Occam's razor is about looking at things as simply as possible and avoiding unnecessary complexity.

It is a tool that helps us to choose the most probable explanation by favouring the simplest theory that explains all the relevant facts.

The importance of simplicity in philosophy

The importance of simplicity in philosophy cannot be underestimated. Occam's razor serves as a guide to avoid unnecessary complexity. A simpler theory is often easier to understand and test, which makes it particularly valuable in science. The principle of simplicity helps to focus on the essentials and avoid distractions caused by unnecessary assumptions. It is a tool for recognising that the simplest way is often the best way, a fact that Leibniz also emphasised.

History: What are „entities”?

Even ancient philosophy struggled with the question. For Aristotle, entities (ousia) are essentially the concrete individual things and their respective form or essence, which he regards as the fundamental basis of all reality. This is how he explains how the world we experience actually exists. In doing so, he departs from the theory of ideas of his teacher Plato.

Platonic solution: There is a separate world of ideas (forms). Everything we see in our world (concrete horses, trees, tables) is only an imperfect reflection of these perfect, eternal, and invisible „ideas” or „universals” (e.g., the „horse-ness,” the „table-ness“). The real reality is the ideas; the individual things only become real at all through their participation (methexis) in these ideas.

Aristotelian solution: Aristotle rejects this separate world of ideas. For him, the „forms“ (that which makes a thing what it is) only exist in the individual things themselves. These individual things (or substances, ousia) are the fundamental reality.

The „entities“ in his ontology are therefore primarily concrete, individual things: this person, that horse, that table. Aristotle distinguishes this first substance (the individual things) from the second substance, which refers to the genus or species of the individual (e.g. the genus „man“ or the species „man“).

To summarise: The „entities“ are the individual substances. Universals do not exist separately, but only as immanent forms in these individual things.

The universals controversy

The universals controversy was the central philosophical debate of the High Middle Ages (ca. 11th-14th century). The question was: Do general concepts such as „man“, „justice“ or „beauty“ have their own real existence? Or are they just names or thoughts?

Three main positions crystallised:

1.       Extreme Realism (Platonic Realism):

Thesis: universals really exist, independently and before individual things (universalia ante rem).

Representatives: Above all Anselm of Canterbury. This position was rather uncommon in the Middle Ages, as Plato's theory of ideas was difficult to reconcile with the Christian doctrine of creation.

2.       Moderate realism (Aristotelian realism):

Thesis: universals exist in real terms, but only in the individual things (universalia in re). They are the common form or the common essence that exists in many similar individual things.

Proponent: Above all Thomas Aquinas. He combined Aristotle with Christian theology. The species „human being“ exists in every single human being as its essence. God did not create each person individually, but the nature of man, which is realised in many individuals.

3.       Nominalism (conceptualism):

Thesis: universals do not exist in a real and independent way. There are only individual things.

a.       Extreme nominalism (Roscelin de Compiègne): Universals are mere names (flatus vocis - „breath of voice“), smoke and mirrors without any reference to reality.

b.       Conceptualism: Universals exist as concepts (conceptus) in our minds, which we form through abstraction from experience with similar individual things. They have a mental, but no external reality.

The thinker: William of Ockham (1288-1347)

William of Ockham is probably the sharpest and most influential representative of nominalism (or conceptualism).

His position is the radical application of the principle „Entia non sunt multiplicanda praeter necessitatem“ mentioned in the introduction to the problem of universals:

Criticising realism: Ockham argues that the assumption of real existing universals (whether ante rem or in rem) is completely unnecessary. It multiplies entities for no compelling reason. All we need to observe and explain in the world are individual, concrete things and the signs we use for them.

His solution (conceptualism):

Only individual, concrete substances and their individual, concrete properties (qualities) exist in the external world. There is no „humanity“, only individual people. There is no „redness“, only individual red things.

A universal (e.g. „human being“) is a sign (signum). More precisely: a mental concept (conceptus mentalis) that naturally (not by convention) stands for many individual things.

This concept arises in the mind through a process of abstraction: through the perception of many similar individual things (e.g. many individual people), the intellect automatically forms a general concept that stands for all these individuals.

For Ockham, a universal is therefore only a thought thing (ens rationis), a sign in our mind that fulfils a function in our language and our thinking. It is not an independent metaphysical entity in the world. Ockham effectively ended the universals controversy by dismantling the realist position with his „razor“. His nominalist/conseptualist view that only the individual is real and that general concepts are tools of the mind became the predominant doctrine of the late Middle Ages and paved the way for the empiricist and modern scientific view of the world, which also only works with observable individual phenomena.

His philosophical criticism of unnecessary assumptions and his call for simplicity in the theory of science have endured to this day.

The formulation of Occam's razor

Occam’s razor, although often attributed to William of Ockham, already existed in a similar form before him. However, it owes its popularity to Occam’s consistent application of the principle of parsimony. The formulation that „entities should not be multiplied unnecessarily“ is central to understanding how Occam’s razor should be used to arrive at the simplest explanation.

The classical definition

The classical definition of Occam's razor states that, among competing hypotheses, the simplest theory with the fewest assumptions should be favoured. This definition emphasises the importance of parsimony and simplicity in the search for the best explanation of a phenomenon. Occam's Razor helps to avoid unnecessary variables and hypotheses, resulting in a simpler and more understandable theory. I support you in integrating this philosophically based insight into your everyday life.

Variations of the formulation

There are different variations of the formulation of Occam's razor, but all emphasise the principle of simplicity. Some versions state that the simplest explanation is the most probable, while others emphasise that unnecessary entities should be avoided. Regardless of the exact wording, the core idea remains: Look for the simplest answer and favour it. Using Occam's Razor will help you recognise the essentials.

Principle of economy instead of principle of variety

Occam's Razor has had a far-reaching influence on scientific theory. It serves as a guideline for the development and evaluation of scientific hypotheses. Scientists use Occam's razor to choose between competing theories and favour those that make the fewest assumptions. The principle of simplicity helps to make complex issues easier to understand. A simpler theory is often easier to test empirically.

The principle of parsimony, which is opposed to the principle of diversity, is the core of Occam's razor. Instead of maximising the variety of explanations, the principle of parsimony focuses on finding the simplest explanation that takes all relevant facts into account. William of Ockham argued that unnecessary complexity should be avoided as it often leads to error and confusion. The simplest theory is often the most probable.

Modern applications of Occam's razor

Occam's razor is widely used today in various disciplines. From computer science to decision-making, it serves as a tool to simplify complex problems and find efficient solutions. The simple logic that favours the simplest explanation has proven invaluable in bringing clarity to confusing situations. The use of Occam's razor is a philosophy of clarity.

Comparison with other philosophical approaches

Occam's razor stands in contrast to philosophical approaches that emphasise complexity and complexity. While some philosophical schools celebrate the diversity of possible explanations, Occam's razor favours the simplest theory that can explain all observed phenomena. This philosophically grounded approach has implications for the way we form and evaluate scientific hypotheses and helps us to avoid unnecessary assumptions. William of Ockham taught that we should make do with the simplest explanation.

Ockham in modern philosophy

Occam’s razor also plays an important role in modern philosophy. It is used to evaluate metaphysical theories and to ensure that philosophical arguments are as simple and clear as possible. Occam’s razor helps to avoid unnecessary complexity and to focus on the essential questions. William of Ockham taught us that we should avoid unnecessary entities. I support you with clarity in understanding this principle.

Influence on problem solving

The impact of Occam's razor on problem solving is significant. By encouraging us to eliminate unnecessary variables and assumptions, it helps us to focus on the core elements of a problem. This leads to more efficient and effective solutions. William of Occam's Razor helps us to find the simplest theory that explains all the relevant facts, an approach that has applications in many fields.

Occam's razor in computer science

In computer science, Occam's razor is used to simplify algorithms and models. The simplest solution is often the most efficient and robust. This is particularly important in certain areas where Occam's razor helps:

·         avoid unnecessary complexity

·         develop generalisable solutions

The simplest explanation is often the most probable.

Application examples of the principle

Occam's razor is used in many areas. It is particularly useful in the following situations:

·         In science, to choose between competing hypotheses.

·         In medicine, it helps with diagnosis by finding the simplest explanation for a patient's symptoms.

In addition, Occam's Razor can help us in everyday life to simplify complex problems and make more efficient decisions. Occam's Razor is a tool for looking at things simply.

Occam's razor can also be used in practical decision-making. When we are faced with a difficult choice, the principle can help us to simplify the options and choose the most likely solution. By eliminating unnecessary assumptions and focussing on the essential facts, we can make more informed and efficient decisions. Keeping things simple helps when making decisions.

FAQ

What does Occam's razor say?

Occam's razor says that when there are competing hypotheses, the simplest theory with the fewest assumptions should be favoured. This principle of parsimony helps to avoid unnecessary complexity and to concentrate on the most probable explanation. Occam's Razor is a tool to consider facts as simply as possible.

What is the principle of parsimony?

The principle of parsimony, also known as the principle of parsimony, is the core principle of Occam's Razor. It states that we should choose the hypothesis that requires the fewest variables and assumptions. A simpler theory is often more likely to be correct because it is less prone to error. The simplest theory is often also the most elegant.

Why razors? So, what does the principle of parsimony have to do with a razor?

The term „razor“ metaphorically refers to cutting off or eliminating unnecessary assumptions and entities. Just as a razor removes whiskers, Occam's razor removes unnecessary complexity to find the simplest and clearest explanation. Using Occam's razor helps to focus on the essentials.

What is the fallacy of Occam's razor?

The fallacy of Occam's razor is to assume that the simplest explanation is ALWAYS the right one. Occam's razor is a useful tool, but it should not be used blindly. It is important to consider all relevant facts and ensure that the simplest theory can explain all observed phenomena. Occam's Razor should be used judiciously.

If Occam's Razor is not correctly translated by „the simplest answer is most likely“, what should the principle be?

A more precise formulation of Occam's razor would be: „Among competing hypotheses that explain a phenomenon, the one that makes the fewest unnecessary assumptions should be favoured.“ It is not about finding the simplest answer, but the explanation that manages with the fewest additional variables. This often makes it easier to test a simpler theory empirically.

So „multiplying entities“ would simply mean having more of them?

Yes, „multiplying entities“ in the context of Occam's razor means introducing more assumptions, variables or concepts into an explanation than are absolutely necessary. Occam's razor advises against assuming unnecessarily many entities, as this makes the theory more complex and less probable. Using Occam's razor helps you to recognise the essentials.

So, if the situation is unclear, I ask, which of the theories is the simplest, i.e. where do the fewest connections need to be proven in order for it to be true?

Exactly. If the facts are unclear, you should favour the theory that requires the least amount of additional evidence to be accepted as true. The theory with the fewest assumptions and variables is usually the simplest and therefore the most likely. Keeping things simple is the key here.

How to use Occam's razor correctly?

To use Occam's razor correctly, there are a few steps:

1.       First, identify all competing hypotheses that can explain a phenomenon.

2.       Then analyse each hypothesis and identify the assumptions it makes.

3.       Finally, choose the hypothesis that makes the fewest assumptions and still explains all the relevant facts.

Using Occam's razor helps to make complex issues easier to understand.