How Occam's Razor Works

William of Ockham, 14th-Century English Monk, Foundational to Modern Science Through Rational Theology and Nature Inquiry

William of Ockham was a 14th-century English Franciscan monk whose reasoning and independent thinking became foundational to modern science. Ockham was a devout man but also a rationalist and an independent thinker at a time when rationalism and the Church were at odds. He challenged not only Church teachings but also the Church's wealth and worldly power, even arguing that religious orders should adhere to the same vow of poverty that monks, including himself, did.

Monk William of Ockham Challenged Church's Wealth and Power

Ockham’s criticism was radical in that he bluntly confronted Church leaders for accumulating money and political power, advocating instead for poverty among church members. His ideas and his sustained critique of authority brought him into direct conflict with Pope John XXII.

Controversial Rationalism of William of Ockham

Ockham’s rationalism was unusual for his time. He questioned the deep-seated medieval synthesis, a view championed by Thomas Aquinas, which held that all human understanding and knowledge ultimately derived from God. Instead, Ockham insisted that things are recognized as such by human cognition, not by divine origin or will. While remaining a believer, he separated rational inquiry from theology, arguing that rationalism should not be applied to God, who should be approached solely through faith, not reason. This position created controversy but laid critical groundwork for separating science from religious doctrine.

William of Ockham's Excommunication and Subsequent Asylum in Munich

Due to his relentless challenges, William of Ockham was excommunicated in 1328 along with several fellow Franciscans. Fleeing, he sought and received asylum in Munich under the protection of Emperor Louis IV. Ockham did not submit meekly; he wrote papers denouncing Pope John XXII as a heretic—a bold and dangerous move. Ultimately, Ockham's ideas gathered support, even though he paid a steep personal price for his defiant and rational stance.

Occam's Razor Principles

Ockham's Concise Distillation of Aristotle's Ideas

Although the core notion of Occam’s Razor predates Ockham—with roots in Aristotle and the medieval scholars who followed—Ockham distilled earlier thoughts into a clear, concise aphorism accessible even today. He summarized centuries of philosophical development with the principle: “plurality should not be posited without necessity.” Put simply, he cautioned against adding elements to an explanation unless they are absolutely required.

Aristotle on Simplicity: Fewer Means Indicate Perfection

Aristotle first articulated the idea that simplicity signals perfection, suggesting that the more perfect something is, the fewer means it requires for its operation. Medieval scientists and theologians like Robert Grosseteste echoed and expanded upon this: the best explanations or demonstrations use the fewest assumptions or premises to account for observed phenomena.

Medieval Theologian-Scientists' Influence on Ockham's Principle

Ockham wasn’t the only thinker in his era advocating this approach; theologians such as John Duns Scotus further developed the principle of parsimony, and philosophers between Aristotle and Ockham championed simplicity. Ockham, however, made the idea famous by restating it in an immediately graspable and practical form—a “razor” for scraping away unnecessary complications.

Occam's Razor: Rooted In Empiricism Over Abstract Reasoning or Doctrine

William of Ockham Rejected Aquinas's Medieval Synthesis, Claiming all Human Knowledge Wasn't Traceable to God

Ockham fundamentally challenged the dominant medieval synthesis by Thomas Aquinas, which traced all causality—and with it, all knowledge—back to divine will. Aquinas applied both philosophical and theological reasoning, asserting that every effect could be traced to God as the ultimate cause.

William of Ockham: Understanding From Cognition/Sensory Perception, Not God's Will; God Approached by Faith, Not Rational Methods

Ockham, by contrast, argued that our concepts arise from our own cognition and sensory perception. He did not c ...

Empiricism, Asserting Sensory-Experienced Phenomena As Real and Knowable, Became a Scientific Cornerstone Alongside Occam's Razor

Josh Clark and Chuck Bryant discuss how modern science is fundamentally based on combining Occam’s razor—choosing the simpler explanation among competing hypotheses—with empiricism, the view that our senses are the path to knowing what is true. They explain that William of Ockham is often seen as an empiricist, someone who asserted that things must be experienced through the senses to be accepted as real.

Bryant humorously lists the senses—if something can't be seen, smelled, tasted, or felt, it’s not accepted as real. This empirical approach means that if there’s no empirical evidence, the claim is dismissed. Clark notes that modern scientific practice relies on these two principles: favoring simplicity and requiring sensory verification.

Clark brings up Ernst Mach, an early physicist who doubted the existence of molecules and atoms. Mach argued that because these entities were undetectable by human senses at the time, they shouldn't be considered real. Bryant defines this attitude as positivism, an extreme form of empiricism rooted in Occam’s razor, where only what can be proved empirically is recognized as existing.

Occam's Razor vs. Theology: Simplicity Depends On Perspective

The hosts explore how Occam’s razor enters territory well beyond science and empiricism, particularly in debates about theology and the existence of God. Bryant lays out how creationists often use Occam’s razor to argue that God creating the universe in seven days is simpler than the scientific explanation of the Big Bang and evolution. For creationists, Occam’s razor thus counts as proof of God’s existence because, in their view, divine creation is the simplest explanation.

Clark notes that, conversely, atheists employ Occam’s razor to argue against ...

Occam's Razor Misused to Disprove Arguments By Favoring Simpler Explanations

Many Misuse Occam’s Razor to Claim Simpler Explanations Are True

Josh Clark and Chuck Bryant discuss a common misuse of Occam’s razor, where people claim that the simplest explanation is the true one and use this claim to dismiss more complex ideas. For example, Bryant describes people explaining photographic “orbs” as nothing more than a camera error or flash reflecting off water vapor, dismissing any other explanations, such as ghosts, solely because the alternative is more complex. Similarly, Bryant jokes about insisting that Oswald acted alone in the Kennedy assassination simply because that is the simplest explanation.

Intended As a Guide, Not a Tool For Establishing Truth or Disproving Ideas

Clark emphasizes that using Occam’s razor to disprove other people’s points is a complete misuse of its original intent. The principle was never designed to prove or disprove ideas; rather, it is a heuristic, a rule of thumb, to guide thinking toward simplicity. It suggests not to complicate matters unnecessarily, but it does not declare that a more complex explanation must be false. Clark clarifies that a true skeptic uses Occam’s razor to consider explanations, not to claim one is proven true or another is disproven. The principle is subjective, helping compare theories rather than decide absolute truths.

Skeptics Should Use Occam's Razor to Compare Explanations Without Claiming one Is Proven or Another Disproven

Clark further explains that instead of claiming something is disproven because it isn’t the simplest answer, skeptics should use Occam’s razor to compare the plausibility of explanations. For example, when encountering a photo with an unexplained orb, a skeptic would acknowledge that while scientific explanations like light refraction are simpler and empirically supported, the existence of ghosts is not categorically disproven—just less supported. Clark asserts that skepticism means remaining open-minded to even seemingly fantastical explanations, while still logically preferring the explanation that rests on fewer and better-established assumptions.

Einstein vs. Lorentz: Occam's Razor In Choosing Relativistic Explanations

Lorentz and Einstein Agreed On Time Dilation Math Near Light Speed but Differed In Explaining It

Chuck Bryant points out the example of physicists Lorentz and Einstein, both of whom mathematically concluded that as something approaches the speed of light, time dilates. However, their explanations diverged.

Lorentz Linked the Effect To Ether Changes, an Unobservable and Empirically Unsupported Substance

Lorentz attributed the phenomenon to changes in the ether, a hypothesized, unobservable substance filling space whose existence could not be measured.

Einstein's Theory Simplified by Avoiding Unverifiable Ether

Einstein, on the other hand, achieved the same mathematical results while avoiding any reference to the ether. He famously dismissed its involvement, favoring explanations grounded only in observable phenomena.

Einstein's Framework Accepted For Elegant Explanation Without Unnecessary Assumptions

As a result, the scientific community adopted Einst ...

Occam's Razor Subjective; Lacks Objective Criteria for 'Simplest' Explanation

Chuck Bryant and Josh Clark discuss how Occam's Razor relies on subjective judgment when determining what qualifies as the "simplest" explanation. For instance, in the case of a mysterious light in a photograph, one person may say "ghost" is the simplest explanation, while another counters with "photographic mishap." The debate itself reveals there is no clear, objective standard—whether "ghost" or "mishap" is deemed simpler is a matter of opinion. Bryant emphasizes that there is “no right or wrong here,” and Clark notes that the absence of a universal metric for evaluating simplicity makes the principle inherently judgment-dependent. Different domains may weigh factors like number of assumptions, explanatory power, or familiarity differently, but no single scale for simplicity exists across all fields, making the application of Occam’s Razor always a matter of perspective.

Universe's Simplicity Might Be a Human Projection, Not an Objective Reality

Clark contends that the preference for simplicity is a human value, not an absolute truth about the universe. Simplicity as a guiding principle or as a mark of perfection is a man-made concept. The universe may be any degree of complex, and just because humans prefer or notice simplicity does not mean nature is organized around that ideal. For example, photosynthesis is a complicated process, yet it may actually be the simplest way for plants to produce food given the constraints of the natural world. Similarly, biological features that appear superfluous—like a shark’s extra fin, a cow’s multiple stomachs, or humans’ two kidneys—could be essential for the functioning of larger systems, even if humans do not fully understand their necessity. The lack of comparison points—such as a cow with just one stomach—means we cannot objectively declare one configuration simpler or better.

Some Scientific Questions Defy Occam's Razor Due to Equally Simple Explanations or Lack of Guidance

Some scientific questions cannot be resolved by Occam’s Razor at all, especially when competing explanations are of similar simplicity. Clark uses historic astronomy as an example: the Ptolemaic (geocentric) model, where Earth is at the universe’s center, and the Copernican (heliocentric) model, with the Sun at the center, are mathematically comparable in complexity. Thus, Occam’s Razor can’t determine which is correct—empirical observation is needed. Clark emphasizes that complexity is not a sign of error: just because an explanation is more complex does not make it incorrect, nor is the simpler always more accurate. Therefore, Occam’s Razor is limited in its ability to dictate truth across all fields.

Choosing Simpler Ai/Ml Models Offers Practical Advantages

When engineering artificial intelligence or machine learning systems, choosing simplicity often brings real-world benefits. Engineers frequently prefer simpler models, such as decision trees with fewer splits, because these systems are less likely to malfunction and require less comput ...