Ontology vs. Epistemology: Differences & Examples

Instructor: Aida Vega Felgueroso

Aida has taught Spanish at the University in Italy. Spanish is her mother tongue and she has a master's degree in Spanish Language and Literature.

Let's look at two branches of philosophy: ontology and epistemology. In this lesson, we will discuss their differences and similarities and the most influential thinkers of each branch.

Philosophy, the Love of Knowledge

The Greek word philosophy means love for knowledge. A philosopher is someone who loves to know and understand the world. Obviously, the world around us is very large and complex; so philosophy, from its beginnings in ancient Greece, has been divided into various branches focusing on different aspects of the world. Two of these branches are ontology and epistemology.

Pythagoras, who is credited with creating the word philosophy.

Ontology, the Theory of Being

Ontology, in Greek, means study, theory, or science of being, that is, of that which exists.

It is possible to see, from this definition, that ontology is a fundamental branch of philosophy and one of the oldest. Ontology, in practical terms, studies the existence or non-existence of things, and moreover, how things that exist relate to each other.

The questions that ontology poses are some of the oldest questions asked by mankind: Does God exist? Do ideas, memories, and emotions exist? Do numbers exist? And, if God, memories, or numbers exist, how do they relate to trees or stones?

These are not easy questions to answer!

In order to study these concepts, ontology divides all things into two large groups:

  • Concrete Entities: like trees or stones.
  • Abstract Entities: such as God or ideas.

Logically, it is not possible to study the two types of entities in the same way because they have different characteristics.

Ontology, like all branches of philosophy, can relate to different fields of knowledge. For example, the ontology of medicine looks deeply into what disease is, what characteristics it has, and how we perceive it. The ontology of law examines the characteristics of the law and what differentiates it from other systems, such as customs.

Lately, the ontology of computer science has grown so much. It studies the entities that exist within the computer science field and how they relate to each other.

Philosophers Who Dealt with Ontology

Ontology is a very old branch of philosophy. That is why all the philosophers of Ancient Greece dealt with ontology. Pre-Socratic philosophers were ontologists who tried to determine what exists and what does not. For example, Empedocles (490-430 B.C.) said that there are four universal elements, earth, water, fire, and air, moved by the forces, love and hate. All things in the world were born of the relations of these six entities.

Ontologists Aristotle (384-322 B.C.) and Plato (428-348 B.C.) classified these entities into groups and tried to identify common characteristics.

Aristotle and Plato.

In more recent times, the philosophers Husserl (1859-1938), Heidegger (1889-1976), and Hartmann (1842-1906)studied and developed ontology.

Epistemology, the Study of Science

Epistemology means study of knowledge. However, we must bear in mind that for the Greeks there were two types of knowledge:

  • doxa: vulgar knowledge, which is based on subjective observance and opinion. For example: If I look out the window, I know it rains.
  • episteme: rigorous knowledge, which is acquired from objective analysis and study. For example: After studying, I know what causes the rain.

Epistemology deals with the second type of knowledge. That is why it is sometimes said that epistemology is the branch of philosophy that studies science.

Philosophers Who Dealt with Epistemology

As with ontology, epistemology was also studied from the beginning. Therefore, we can find examples of epistemological questions from the philosophers of antiquity.

But the greatest contribution to epistemology comes later. The French philosopher René Descartes (1596-1650) is often considered one of the founders of modern epistemology. His views are based on a principle that is known as epistemological fundamentalism. This is a thesis that says that human knowledge has to rely on truths that can not be denied.

Descartes was able to enunciate an irrefutable truth. He expressed it in Latin: Cogito, ergo sum. That is, I think, therefore I am. If a person doubts, it is undeniable that he thinks. Therefore, if a person thinks, he must necessarily exist. From this statement, Descartes' attempted to build the criteria that could establish some truths as undeniable.

In reality, it is very difficult to establish truths that can not be contradicted. The world around us certainly seems real, especially concrete entities that we can touch, feel, and see. However, it is possible for illusions to be sensed, such as mirages that are interpreted by our eyes. How did epistemologists get around this contradiction?

In the 20th century, Karl Popper (1902-1994) introduced a concept that helped to further develop epistemology.

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