I. Definition

Ontology is the study of being. It focuses on several related questions:

  • What things exist? (stars yes, unicorns no, numbers . . . yes?)
  • What categories do they belong to? (are numbers physical properties or just ideas?)
  • Is there such a thing as objective reality?
  • What does the verb “to be” mean?

Some of these questions may seem painfully abstract and not very useful, but they are and always have been enormously important to some philosophers, especially to those who believe in foundationalism. Foundationalist philosophers believe that to arrive at truth it is necessary to start with the most fundamental issues—to be sure about the foundations of philosophy–and then work our way up from there to more specific questions. If you believe in foundationalism, then probably the most important questions are ontological questions!

Ontology is also highly relevant to religions and spirituality. No matter what your beliefs about spirituality, they have an ontological dimension. All of the following are ontological statements:

  • Everything is made of atoms and energy
  • Everything is made of consciousness
  • You have a soul
  • You have a mind


II. Ontology vs. Metaphysics

Ontology is generally considered to be a sub-field of metaphysics. Metaphysics has many definitions, but it means something like “the study of the fundamental nature of reality.” Clearly, this is closely related to ontological questions. There’s an overlap between ontology and metaphysics, which covers questions like “what is existence?” or “how do things exist?”

However, as a rule of thumb we can say that ontology asks what questions, while metaphysics asks how questions.


The difference between ontology and metaphysics may be easier to understand if we look at a made-up world. Take a fantasy world like J.R.R. Tolkien’s Middle-Earth. Its ontology is different from ours because it has all kinds of things in it like elves, orcs, and dark lords, that don’t exist in our world. But its metaphysics are different because it has a fundamentally different nature, involving magic. Middle-Earth doesn’t just have different things in it; the things play by different rules. Ontology studies the things, while metaphysics studies the rules.


III. Ontology vs. Epistemology

Ontology and metaphysics both get confused with epistemology, but epistemology is easier to separate out. Epistemology is the study of knowledge, of how we know what we know. Whereas ontology and metaphysics are about reality, epistemology is about how human consciousness can interact with that reality.

Ontology Metaphysics Epistemology

Do souls exist? Are they the sort of things that obey physical laws?


Is there a God?

What physical laws would have to be true in order for souls to exist?


What rules, if any, govern God’s actions?

How can we know whether souls exist?


Can human beings ever know whether there is a God?

IV. Famous Quotes About Ontology

Quote 1

“Beyond the fiction of reality, there is the reality of the fiction.” (Slavoj Zizek)

Slavoj Zizek is a Slovenian philosopher, highly influential in certain philosophical circles. (Though other circles dismiss him entirely; that’s philosophy for you!) His ontology is hard to describe in its specifics, but for starters, like many philosophers, he sees a deep split between reality and language. Language separates the world into all sorts of different parts and categories, but those categories are little more than useful fictions. The fictions, though are real–real stories about fictional categories.  Or, in other words, everything we can say about reality is fictional, but language itself is a reality of its own.

Quote 2

“You do not have a soul. You are a soul. You have a body.” (Anonymous)

This quote, often incorrectly attributed to C.S. Lewis, probably comes from a Quaker magazine in the 1890s. It argues for a very particular ontological perspective: souls exist (clearly an ontological claim), but they are not the sort of things that you can have or own (an ontological/metaphysical claim). Bodies, on the other hand, do belong to that category. But the consciousness currently reading these words is a soul.


V. The History and Importance of Ontology

In a sense, ontology is one of the oldest forms of philosophy. An ape climbs a tree hoping to find wild figs; some would say that the ape’s behavior suggests the ontological question of whether there are any figs up there. That’s not a very elaborate or philosophical sort of ontology, but it’s the same general sort of question.

The Greek philosophers were somewhat obsessive ontologists: in their desire for complete knowledge of the world, they tended to categorize things and argue about what the categories should be and what should belong to them. For example, Aristotle made a highly influential argument about the “Ladder of Nature,” which placed non-living beings at the bottom (for example, rocks and clouds), then moved up to plants, then animals, and finally human beings. This is an ontological theory of the natural world, and it had a huge impact on medieval philosophy and far-reaching implications for Aristotle’s moral theory.

This sort of ontology wasn’t practiced only in the West: Arab, Indian, and Chinese philosophers also studied the world around them, deduced general “rules” of existence, and tried to categorize things. Thanks to the global trade networks of the ancient and medieval worlds, these philosophers all influenced one another; Arabs argued about Aristotle, Romans argued about the Indian Vedic traditions, and so on. These traditions of ontology were never entirely separate from each other.

The scientific revolution brought about a deep change in ontology. Many of the early scientists realized that the only way to be certain that they were discovering truths about nature was to forget about anything (at least while doing science) that couldn’t be tested and proven, which seems to include supernatural beings, divine forces, and souls. Only physical laws, matter and energy seem to be measurable and obey reliable laws. Many of them also had religious beliefs, and some of them even carried out experiments concerning the supernatural, but for the most part, they found that it was necessary to assume that only the material world exists in order to carry out sensible experiments and derive laws of nature from them.

This scientific ontology has been so successful in terms of understanding nature and controlling it that it has come to dominate the way we think about everything, including, for some people, religion. For example, there are institutes in the world that seek to “prove” or “disprove” the existence of God by experiment. But this seems a little confused and certainly would have surprised both believers and scientists during the scientific revolution. Most of them would have told you that God, if he/she/it exists, is not the sort of thing that can be proven or disproven by experiment — that God belongs to a different ontological category from the natural phenomena that we observe in science.


VI. Ontology in Popular Culture

Example 1

In the original Star Wars movies, the Force is presented as a semi-mystical or magical force, an “energy field created by all living things” that seems to go beyond natural law as we know it.  But in the prequels The Force is presented in more scientific terms; we learn that there are tiny microorganisms called “midi-chlorians” living in the bloodstreams of human beings. This makes a difference for the ontology of the Star Wars universe because it adds a new kind of being, and it also changes the metaphysics because the Star Wars universe now plays by slightly more familiar, scientific rules.

Example 2

Game of Thrones is a rare example of a fantasy story with a very strange ontology but very realistic metaphysics. In the story, there are dragons, giants, zombies, and all sorts of other fantastic creatures that don’t exist in the real world. However, all these creatures behave according to fairly familiar laws, which gives the series a more realistic feel. At certain points, the show includes magic, but it is relatively rare and always seems surprising because otherwise the show is hyper-realistic. Due to the relative absence of magic, the show can be said to have a pretty realistic metaphysics in spite of its fantasy ontology.


VII. Controversies

Ontology: Should We Even Bother?

Many students fall asleep during ontology lectures. Even many professional philosophers do not practice ontology. They argue that “being” is a vague idea, maybe just an artifact of language, and that there’s no point in analyzing it intensively; the verb “to be” is just a useful tool that human beings have evolved in order to get through their daily lives. It doesn’t have a specific meaning and therefore ontology is searching for something that isn’t there. Some also argue that it’s pointless for philosophers to try and work out what exists in the universe — that instead we should leave that to scientists.

Of course this argument meets stiff resistance from many philosophers, which treat ontology as central; remember the foundationalists from section 1? They would not agree that ontology is pointless.  Moreover, ontology and metaphysics have gained some new energy lately, thanks to the mystifying implications of quantum physics and the science of consciousness, which are turning many scientists into philosophers, and vice-versa.


Ontology asks ____, while metaphysics asks _____.





Ontology is the study of . . .





“You have a soul.” This is primarily a statement about . . .





Aristotle’s ontological theory included the idea of a . . .