Occam's razor, or the law of parsimony, states that the simplest explanation for any given data is most likely the correct one.

Some have attempted to use Occam's razor in a metaphysical sense, to say that, for example, God is unlikely because to assume that God exists introduces additional, and unlikely, complexity. However, I'm wondering how this can be applied. The Wikipedia article for Occam's razor gives a few justifications, but the only justifications that seem to work for metaphysics are the mathematical ones (correct me if I'm wrong), for all the others are either empirical, which is not related to metaphysics, or "aesthetic," which does not seem to be very rigorous.

The mathematical justification seems to state that because the probability of the assumptions needed, for example, to say God exists is less than 100%, each additional assumption decreases the probability of God. However, I have a few questions about this.

  1. Why assume that the probability of any two given metaphysical ideas are the same? For example, how can you assign any probability to whether or not God exists? Why assume a uniform distribution any more than any other distribution?

  2. Why assume that the assumptions to be made have a non-100% probability? Of course, you could then say that they are not really assumptions, but how could you justify that they really are assumptions at all?

  3. Why is there a distinction between "positively defined" and "negatively defined" assumptions? For example, to say that God does not exist, you would have to assume that there is no being that exists that is all-powerful, no being that exists that is all-knowing, etc. It seems fairly easy to come up with additional assumptions that have to be made even in a "negatively defined" case, and how can you meaningfully assign probabilities to these assumptions?

I've also seen justifications based on minimum description length and Kolmogorov complexity, but I don't see how these computationally-based ideas have anything to do with metaphysics. How can one say that a metaphysical reality is in any way defined in a computational sense? Do simple statements that can be said to define metaphysical realities, such as x is true, y exists, etc., somehow link to computation?

While I don't really see any problems to these objections, I assume that there is at least some validity in using Occam's razor in a metaphysical way, given that so many well-known (and lesser-well known) atheists, such as Richard Dawkins, base their beliefs off of it. So what, if anything, is wrong with my objections?

  • 1
    Empirical is not unrelated to metaphysics, it is a basis of it, although not the only basis if one is not an empiricist. What we are looking for is a plausible and parsimonious explanation of the totality of our experience, empirical and otherwise, if any. If we can find an equally plausible, but more parsimonious, metaphysical picture without God then we are justified in dropping him from the picture. it is a pragmatic justification, not a metaphysical one.
    – Conifold
    Commented Jun 19, 2019 at 22:49
  • "the simplest explanation for any given data is most likely the correct one." So wouldn't that mean Occam's Razor can't be used metaphysically? ... there's no data by definition. What would be an example of a mathematical justification for something metaphysical? With regard to god I need to know, and is not defined above, what 'exists' means? How does something exist in supernatural domain since supernatural (metaphysical) means unmeasurable? Does the statement 'god is metaphysical' or 'god does not participate in the natural world' mean that god does not exist? Commented Jun 20, 2019 at 4:41
  • Occams' Razor is used all the time in metaphysics. It tells us nothing about whether there is a God but it does lead us to believe there are not two of them. The suggest that the correct 'explanation of everything' will be the most parsimonious. As metaphysics is all about reductution it is bound to be a search for the most parsimonious theory, Thus, for instance, we can reject Democtritus' 'atoms and void; model for having way too too many theoretical entities. .
    – user20253
    Commented Jun 28, 2019 at 15:37
  • I don't think there is anything wrong with your mathematical observations but as I suggest in my answer the Razor has metaphysical applications to the problem of universals, a problem neither mathematical nor necessarily involving God and not specially tied to aesthetics even if as some suppose there are aesthetic universals. 'The' problem of universals ? There are many but it's clear with which problem Ockham was primarily concerned. Best - GLT
    – Geoffrey Thomas
    Commented Dec 20, 2019 at 13:47
  • I feel the question here is confused. There is a general question about Occam's Razor and a specific question about God. The latter is easy since the Razor tells us nothing about God, while the former is more interesting.
    – user20253
    Commented Dec 20, 2019 at 14:10

10 Answers 10


Let me point out, first, that Occam's Razor is not a law; it's a rule-of-thumb that has more to do with pragmatics and aesthetics than necessity. It's a good rule of thumb, sure, but it is based on an a priori belief that the universe as a whole conforms to what human minds count as parsimony.

That being said, the main issue with applying Occam's Razor to metaphysics (or to anything, really) is that the concept of parsimony is sensitive to context. Parsimony is a conservation issue — by which I mean it tries to create a constant, minimal, necessary and sufficient ground for a field of knowledge — and so we need to consider what qualities we are trying to conserve before we can apply it fruitfully. In the atheist/theist divide pointed at above, atheists generally focus on the material/physical universe to the exclusion of everything else, and within that context it may very well be more parsimonious to assume there is no God. Theists, by contrast, are not overly concerned about the physical world. They focus on the social/moral world — the world of human experience and behavior — and within that context it may very well be more parsimonious to assume there is a God. God may be an unnecessary explanation for the Big Bang, but are Newton's Laws useful and relevant to an understanding of ethics?

The conflict between these groups is seemingly endless because both sides refuse to engage the context of the other: theists dismiss valid statements of science, while atheists reject theological moral, philosophical, and experiential arguments out of hand. There will not be a resolution to the issue until all those involved are willing to engage a larger context, and we cannot really talk about parsimony until that occurs.

  • 2
    A sensible answer. Reminds of another comment by @CriglCragl that «Western thought is still stuck in the idea religious claims are epistemological»
    – Rushi
    Commented Jul 29, 2019 at 16:31
  • Good answer, but I want to nitpick: "Theists, by contrast..." should necessarily assume that there is a god instead of "may very well", by definition of their own 'theist' quality.
    – user31740
    Commented Aug 19, 2019 at 13:16
  • @William - well, yes, you're right as a matter of definition, but I was talking about the parsimony of the reasoning. Think of it this way... If there was a person with no opinion who was trying to decide whether God existed, then context matters. if s'he is focused on the material/physical world then the idea of God might seem extraneous; if s'he is focused on the social/moral world then the concept of God might seem elemental. S'he would come to beliefs accordingly. Commented Aug 19, 2019 at 14:36
  • @TedWrigley - I would agree with your point. But a person focused on the material world still has to explain what it is and where it came from, so I'm not sure this is a good example.
    – user20253
    Commented Dec 20, 2019 at 14:13
  • 1
    @TedWrigley - There are plenty of theories that don't work. I see no use for them.
    – user20253
    Commented Dec 21, 2019 at 12:41

An interesting point about your question is that Occam first applied the Razor - though the term is not his - to a metaphysical issue, the problem of universals.

Ockham was a nominalist - he denied the existence of "universals." What are they? Let us begin with what they are not. Universals contast with particulars. Particulars are the individual things that populate the universe - you, the hive of the bees in the park, the Eiffel Tower, Planet Earth. Universals are supposed to be the properties that multiple individual things have in common. For example, Socrates and Plato are particulars, and both philosophize. Does that mean that the statement "Socrates and Plato both philosophize" describes three things - the two men plus the universal to which the two individuals belong? Ockham's answer is no. According to Ockham, the two individuals exist and there is Socrztes's philosophizing and Plato's as well. Each of these properties is unique to the individual who has it. There is no universal here - there exists no property of philosophizing that is shared among the particulars. It is the human mind's invention of concepts (in this instance, the concept of philosophizing) that fosters the illusion that universals exist. (Elliott Sober, Ockham's Razors, ISBN 10: 1107692539 / ISBN 13: 9781107692534. Published by Cambridge University Press 2015-07-23, Cambridge, 2015: 9-10.)

This shows how the Razor can be used metaphysically whether considers it a correct use or not. Sober further refers to Ockham's use of the Razor in connexion with the problem of change, of explaining what happens when change occurs. I take change to be in broad terms another metaphysical issue, not least because universals can be invoked in handling it.


I'm not sure this is exactly what you're asking, but it's very much possible to use Occam's razor with religion.

Of these two hypothesis:

  • Humans made a mix of the beliefs and legends of their time about the world and its origin, based on their current knowledge, it stuck orally, and eventually got written in a book that was then described as the original word of God.

  • God spoke to humans, and purposely gave an incomplete and incorrect depiction of the world (no mention of viruses or bacteria, plants created before the sun and moon[1]), and gave incoherent or plain arbitrary recommendations ("never cook a young goat in the milk of its own mother" [2]) instead of recommendations that could be actually useful ("wash your hands regularly and keep you waste far from your house").

which one seems more simple? And if you try to find reasons for God to give factually wrong information in the Bible, that would make your hypothesis even more complex and Occam razor would favor the first one even more.

This doesn't prove God doesn't exist of course, but here Occam's razor can be used for question related to religion (is the Bible man-made or the true word of God?) that can be used for a reasoning about the existence or God.

Though it's not a metaphysical question, and IMO I don't think Occam's razor can be used for something purely metaphysical in the sense that we have no data on any of the hypotheses we want to test.

[1] : Genesis somewhere

[2] : Exodus 23:19

  • Besides the Bible references would you have references to others taking a similar view about Occam's razor? These would support your answer and give the reader a place to go for more information. Welcome! Commented Jun 28, 2019 at 16:31
  • @FrankHubeny My source video is in French, but it has English captions. Here's the link. Occam's Razor is not directly mentioned but he uses Bayesian inference reasoning and it's closely related to Occam's Razor Commented Jul 1, 2019 at 19:19

The same Occam who has a razor named after him also said:

Only faith gives us access to theological truths. The ways of God are not open to reason, for God has freely chosen to create a world and establish a way of salvation within it apart from any necessary laws that human logic or rationality can uncover.

For nothing ought to be posited without a reason given, unless it is self-evident (literally, known through itself) or known by experience or proved by the authority of Sacred Scripture.



He believed that science was a matter of discovery and saw God as the only ontological necessity.

from Wikipedia

For Ockham, the only truly necessary entity is God; everything else, the whole of creation, is radically contingent through and through. In short, Ockham does not accept the Principle of Sufficient Reason.


Emphases added to the original showing Occam using his razor in the context of his calling...


  1. Occam was a theologian
  2. Occam's razor is named after said theologian

People wanting to affirm the second and ignore the first are suffering from acute tunnel-vision or mendacity.

Thought experiment

Here's a list of musicians who objected to Trump using their music.

If William of Occam – the theologian – were alive and found all the great anti-theists using his name to justify their godlessness would he say "It's ok! " or would he issue "cease&desist" orders?

Hint: Check what tough letters he sent the pope for not following the injunctions to poverty in holy-scripture.

  • 1
    I am downvoting the answer because it doesn't directly adress the question and ends with an unrelated afirmation, besides the bad formatting.
    – user31740
    Commented Jul 28, 2019 at 17:39
  • Be my guest 😀😆😈. Yet I appreciate the comment @william. (most down voters hide under anonymous cowardice)
    – Rushi
    Commented Jul 28, 2019 at 17:46
  • @william added emphasis to show the connection with the question. IOW to show how the theologian William of Ockham used his razor as a justification of his faith
    – Rushi
    Commented Jul 28, 2019 at 17:51

The short answer is that it is simply not justified. When it comes to metaphysics, it makes no sense to talk about the likelihood of God. What does it mean for God to have a 60 or 80 or 90% chance to exist? It seems meaningless and ill defined.

The real flaw with theories that you seem to be positing as complex is not parsimony. The real problem is that there is no direct evidence of them. There is no observation or explanation that shows us that God, complex or otherwise, is operating in the world. On the other hand, physical laws, whether blind or otherwise, atleast do exist. One cannot deny their existence and so we operate on the assumption of their existence and don’t postulate entities that we have no evidence of.

No observation that is possible under known physical laws can ever serve as evidence for a process that we cannot observe or detect.


If you are amenable to the musings of Immanuel Kant, I would offer his remarks on exactly this question:

We are not discussing the above-mentioned assertions regarding the immaterial unity of the soul and the existence of a Supreme Being as dogmata, which certain philosophers profess to demonstrate a priori, but purely as hypotheses. In the former case, the dogmatist must take care that his arguments possess the apodeictic certainty of a demonstration. For the assertion that the reality of such ideas is probable is as absurd as a proof of the probability of a proposition in geometry. Pure abstract reason, apart from all experience, can either cognize nothing at all; and hence the judgements it enounces are never mere opinions, they are either apodeictic certainties, or declarations that nothing can be known on the subject. Opinions and probable judgements on the nature of things can only be employed to explain given phenomena, or they may relate to the effect, in accordance with empirical laws, of an actually existing cause. In other words, we must restrict the sphere of opinion to the world of experience and nature. Beyond this region opinion is mere invention; unless we are groping about for the truth on a path not yet fully known, and have some hopes of stumbling upon it by chance.

As for simplicity proper, two things:

  1. A particular consideration regarding the divine nature. Classically, the divine nature is supposed to be partless in some exceedingly important sense. For some, it is enough to say that God doesn't have spacetime parts. For others, it's not enough unless one goes on to say that God doesn't have nonspacetime parts either, where "nonspacetime" is a rough placeholder for the kinds of seemingly disparate terms that occur in analytic/scholastic theology. The argument is this: if there is no necessary being, then there must be an explanation for why there is no necessary being. But if a being actually were necessary, there would be a simple reason why it was as it was, and why it existed: automatically, by default, trivially. If a necessary being didn't exist, though, then also by default, the explanation for what could prevent a truly necessary being from existing would be a more complicated, and in the end absurd-seeming, explanation than the explanation for why a necessary being simply does exist.

  2. In another, mathematically robust sense, abstract simplicity is too generically simple to be concretely simple. Or, the predicate "simple" is not absolute, but must be qualified; perhaps, as with God, there is a point in asking about absolute simplicity nevertheless, but if we mean to juggle whichever metaphysical poems and dialectical experiments there appear to be (and like Legion, they are many...), then perforce at some point, and then many points, we will run into the problem of a supposedly per se simpler explanation that is actually simpler modulo only one important factor, but another explanation is the simpler in terms of yet a different important factor. We see this, most clearly, in the impossibility of deciding whether logic or mathematics is truly more fundamental or all-encompassing (or both), and then whether specific kinds of logic or mathematics are the ultimate elements of our intellectual world (set theory? type theory? category theory? graph theory? algebra? geometry, after all? geometrical logic? first-order logic? zeroth-order logic? n-ordered logic? n-ordered arithmetic? philosophy itself, somehow, no less?).


Good question and I empathize with you. A few points that I feel are relevant:

  1. Mathematically, probabilities are positive proper fractions. You might need to study properties of (proper) fractions if you want to make any headway into the problem.
  2. A specific example from which you may abstract away ad lib. "I need at least 6 chairs, Jalal", said Julio.
  3. A probabilistic interpretation of the novacula Occami is fine, but it's unlikely 🙂 that William of Occam knew anything about mathematical probability.

In fact, Occam (Ockham) himself acknowledged that there is a problem here. In reference to transubstantiation, Ockham disagrees with Aquinas, as described in by McCord Adams (page 164):

Aquinas to the contrary notwithstanding, neither reason, the Bible, nor the determinations of the saints force an endorsement of transubstantiation. It must be upheld only because Innocent III's council and other decretals pronounce in favor of it. Miracles should not be multiplied without necessity. But sometimes in the soteriological realm, it pleases God to violate Ockham's Razor! The nominal definition Ockham offers in his Sentence commentary merely conjoins the items theological consensus had settled upon.

[D11] transubstantiation is the succession of substance to substance (of S2 to S1) where S1 ceases to exist in itself and S2 comes to exist under S1's accidents.

(emphasis added).


Occam's razor is widely misunderstood and misapplied. You might want to consider it in terms of probabilities. If you make n independent assumptions to explain an outcome, with probabilities P1, P2, P3...Pn, then the probability of them all being correct is the product of the individual probabilities, so each time you add another assumption the overall probability of your explanation being correct decreases. As a general rule, therefore, an explanation with fewer assumptions might be more probable than one with more, but that depends on the probabilities of the assumptions being broadly comparable. An explanation with a large number of highly probable assumptions can be more likely than an explanation with only one low-probability assumption. You cannot apply Occam's razor blindly- you must make intelligent assessments of the plausibility of the assumptions in the competing theories.

The problem, therefore, in applying Occam's razor to many metaphysical problems is that the probabilities involved are anyone's guess. Occam's razor is as much subject to the 'garbage in, garbage out' rule as any other reasoning procedure.


Metaphysics and Ockham's razor... I love it. Like a cosmic game of "Name That Tune". With host, Peter E.

"Occam's razor, or the law of parsimony, states that the simplest explanation for any given data is most likely the correct one" - Per Peter E.

"Metaphysics is a branch of philosophy concerned with explaining the essence of things, of the fundamental nature of being and the world and the principles that organize the universe. Metaphysics is supposed to answer the question "What is the nature of reality?" - Per Philosophy.SE/Metaphysics... here.

How few entities might be minimally required to explain all of reality?

Well, Peter E. I propose to Name That Tune... erm, I mean... Explain That Reality... in 1 single non-changeable fundamental entity. (blows on nails, and polishes them on his shirt... there cannot be a candidate answer with fewer than 1 entity)

So Gods, and Dawkins, and all else aside. Focusing on Metaphysics and fundamental reality...

... yes. I suggest sincerely... Reality explained with candidate entity.

Single Candidate Entity

Candidate Universal Fundamental Unit

Identical Copies Populating a lattice


All Spinning In Harmony

Spin Field

From Which All Else is "Emergent"


It is similar to the past suggestions made by Louis de Broglie at the Solvay Conference in 1927 and later repopularized by David Bohm:

Pilot Wave Theory

"In theoretical physics, the pilot wave theory, also known as Bohmian mechanics, was the first known example of a hidden-variable theory, presented by Louis de Broglie in 1927. Its more modern version, the de Broglie–Bohm theory, interprets quantum mechanics as a deterministic theory, and avoids issues such as wave–particle duality, instantaneous wave function collapse, and the paradox of Schrödinger's cat by being inherently nonlocal."

But better. Because it is "voluminous" and therefore more plausible. See, imagine David Bohm's "group wave" as being a deflated balloon.. and inflate it mathematically...

Inflate the deBroglie/Bohm "group wave"

Cool eh? An actual candidate answer to "What is the nature of reality?"... and a total win, if William of Ockham has a say in the matter.

Might be wrong. But if there is a better and more plausible candidate answer to the metaphysical composition of reality... I am unaware of it.

If there is an observation that is not compatible with a reality based on fricitonless spinning immutable wave-sphere-shaped fundamental units, then the suggested candidate answer is incorrect.

IF not... It wins the "Name That Tune Reality Style" with 1 (one) entity. (replicated, and in motion, interacting with nearest neighbours, nothing else).

I leave it in your hands to decide what to think...

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