What Are the Three Main Parts of Metaphysics?


Vincent White

Metaphysics is a branch of philosophy that seeks to understand the nature of reality. It explores questions about existence, causality, time, space, and the relationship between mind and matter.

Metaphysics is divided into three main parts: ontology, cosmology, and epistemology. In this article, we will take a closer look at each of these parts.


Ontology is the study of being or existence. It examines what exists and how things exist. The word “ontology” comes from the Greek words “ontos” meaning “being” and “logos” meaning “study.”

Ontology investigates questions such as: What is real? What are the fundamental building blocks of reality? Are there different kinds of things that exist?

Some philosophers argue that there is only one kind of thing that exists – physical matter. This view is known as materialism or physicalism. Other philosophers argue that there are other kinds of things that exist besides physical matter – such as mental states or abstract concepts like numbers and ideas.


  • Materialism asserts that everything in existence can be explained by physical laws.
  • Dualism asserts that there are two fundamental types of entities in the universe – mind and matter.
  • Idealism asserts that reality is fundamentally mental or spiritual in nature.


Cosmology is the study of the universe as a whole. It explores questions such as: What is the origin of the universe?

What are its properties? What are its ultimate fate and destiny? Cosmology deals with both scientific and philosophical questions.


  • The Big Bang theory proposes that the universe began as a singularity approximately 13.8 billion years ago.
  • The Steady State theory proposes that the universe has always existed and is continuously expanding.
  • The Multiverse theory proposes that there are multiple universes, each with its own set of physical laws.


Epistemology is the study of knowledge and belief. It examines questions such as: What is knowledge?

How do we acquire knowledge? What are the limits of our knowledge? Epistemology tries to understand how we can distinguish between true and false beliefs.


  • Rationalism asserts that reason is the primary source of knowledge and that certain truths can be known a priori.
  • Empiricism asserts that all knowledge comes from experience and observation.
  • Skepticism asserts that we cannot know anything for certain.

In conclusion, metaphysics is a fascinating field that explores fundamental questions about reality. The three main parts of metaphysics – ontology, cosmology, and epistemology – provide different perspectives on these questions. Whether you are a philosopher or simply interested in exploring the nature of reality, metaphysics offers plenty to ponder.