Philosophy 101: The 5 Major Branches of Philosophy Explained

This article explores the philosophical branches, the types of knowledge that exist within the philosophical discourse.

Sep 5, 2023By Antonio Panovski, BA Philosophy

what are the branches of philosophy


Out of all the sciences, philosophy is the most undefined field of study of them all. We can reach an agreement that every special science is defined by its subject of investigation and its methods of examination. However, that’s not the case with philosophy. Some would even argue that, among other things, this lack of a definition is what stops philosophy from becoming a real science.


Although there is no consensus about the definition of philosophy, the branches of philosophy do have a definition. Examining these philosophical disciplines can help explain what philosophy really is. That’s why in this text, we’ll discuss what each discipline is about, and show how they contribute to our understanding of philosophy as its own field of study separated from the sciences.


1. Examining the Universe: Metaphysics

Copy of the bust of Plato, original by Silanion, c.370 BC, via Wikimedia Commons.


One of the first questions ever posed, not just in the field of philosophy but also in science in general, is the question about Being, the question about the first principle, the root cause of all of existence. The discipline that deals with the question of Being is metaphysics or ontology. We can define metaphysics as the study of the existent as existent, or simply define it as the study of Being.


Philosophers of the ancient cosmological period investigated the question of Being. The cosmological period is the period of forming ancient philosophy, and in it, the focus was on uncovering the underlying nature of reality.

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Roughly speaking, there are two schools of thought within metaphysics, each identifying Being in their own way.


Materialism sees Being as made out of material components. For example, Thales thought that Being is water, Heraclitus thought that Being is fire, and so on.


On the other hand, idealism sees Being and the world as made out of something idealistic or spiritual. The famous philosopher and mathematician Pythagoras saw the number as the first underlying principle, while Plato thought that ideas were the first Beings because they are eternal. Material things, says Plato, can be destroyed and perish, but ideas cannot.


Furthermore, there are two variations of idealism: objective and subjective. Plato’s stance is considered to be objective idealism, while the philosopher George Berkeley held the subjective position, claiming that the world surrounding us is a collection of sensations: the content of consciousness.


The Red Tower by Giorgio de Chirico, 1913, via Guggenheim.


Another important distinction exists according to how many Beings fundamentally exist.


Monism states that Being can be only one principle and one basis of reality, which serves as the root cause of all of existence. Heraclitus, who we’ve mentioned before, is a monist. He states that fire and nothing else can be considered the fundamental cause of the universe. Fire is the first and only principle from which everything else is created, and the last point of everything, as everything, eventually, finds its way back to fire in the end.


Dualism states that the universe is based in two primordial principles. Rene Descartes thought that two substances existed in the world: the first one is the mind, and the second is the body. One substance thinks, and one has an extension.


Lastly, pluralist philosophers see the world as containing many Beings. Plato was a pluralist-oriented thinker, as he saw ideas as being the basic underlying principle, and furthermore, there exists an infinite number of ideas. Another pluralist thinker is the ancient philosopher Democritus who believed that Beings are atoms, and there are infinitely many atoms, which means there exists an infinite number of Beings.


2. Examining Knowledge: Epistemology

Portrait of John Locke by Sir Godfrey Kneller, 1697, via The Hermitage Museum.


When being faced with the question of what exists in the world, it’s almost inevitable to ask: how do these thinkers know about Being? How did they get the knowledge of what exists in the world and what doesn’t? How do we know what they’re saying is true?


This is the point where we go from metaphysics to the next branch of philosophy – epistemology, or gnoseology. The term “gnoseology” is derived from the Greek words gnosis, meaning knowledge, and logos, meaning a study, a science. Gnoseology is the field of study that investigates the source, means, criteria, possibilities, and limits of human knowledge.


There are various approaches to what knowledge is and how it is acquired. Rationalism is a branch of epistemology that sees human reason, the “ratio,” as the source of all knowledge and as the ultimate instrument we use when acquiring knowledge. Aristotle and Plato are rationalists, seeing the human mind as able to understand everything in the universe.


Empiricism, on the other hand, claims that all knowledge is acquired through experience, and sees experience as the source of all our knowledge. John Locke and David Hume were empirically oriented thinkers, stating that people are born as a “tabula rasa” – a blank slate with no impressions on it, and that all the knowledge that we acquire throughout life is indeed gained through experience.


These two approaches are strongly opposed, and it’s a debate that’s been going on for centuries, not being able to reach an agreement on whether we gain knowledge from experience, or whether there are some principles in the human mind that are the source of all our knowledge.


Portrait of René Descartes by Frans Hals, c.1649, via Louvre.


There’s also another approach to epistemology – irrationalism. Irrationalism sees the ultimate source of our knowledge as something irrational, and here there are two different sub-categories: voluntarism (taking the will as being the only real source of knowledge), and intuitionism (taking intuition as the proper means of acquiring knowledge).


Epistemology also explores the limits of human cognition and knowledge. Here, there are three basic approaches: dogmatism, agnosticism, and skepticism.


Dogmatism sees human knowing abilities as perfect and argues that man can indeed know the world to the fullest. As opposed to dogmatism, agnosticism claims that humans cannot know the world to the fullest, as we are severely limited in our cognitive abilities. Skepticism serves as a medium option between the two. It just doubts the possibility of getting to know the world, it does not say anything positive or negative. It may be possible to know the universe, but it may be impossible as well. Who knows?


3. Examining Reason: Logic

Bust of Aristotle by Lysippos, after 330BC, photograph by Jastrow, via Wikimedia Commons.


Another branch of philosophy that is closely linked to epistemology is logic. Logic is the study of correct reasoning. The term originates from the Greek word logos, meaning word, reason, thought, or science.


The ancient Greek philosopher Aristotle founded logic, and it was he who formed and developed its foundations and principles. However, he did not have the intention of establishing logic as a separate discipline and science. He did not see it as a science at all! Instead, he thought of it as a mental skill used for reasoning.


Aristotle paid close attention to the way that we think, noticed the principles of our reasoning, and followed the path to how we make conclusions. Introspecting his own thoughts and carefully taking notes was how logic came to be. That’s why he named the book containing the logic corpus Organon, which means an instrument, a tool, or an organ used for reasoning. Whether logic can be considered a separate and distinct scientific discipline or is simply a skill, remains an open question to this day.


Logic includes both formal and informal logic. Formal logic investigates how conclusions follow from premises in a topic-neutral way. It’s a set of formal rules and principles within a system that determines the validity and truthfulness of an argument or conclusion.


On the other hand, informal logic is associated with informal fallacies, critical thinking, and argumentation theory. Arguments in formal logic are expressed in formal language, while arguments in informal logic are expressed in informal language. Logic is a complementary part of any given science, but it plays a central role mostly in philosophy, mathematics, computer science, and linguistics.


4. Examining Morals: Ethics

Bust of Epicurus, late 3rd century – early 2nd century, photograph by Marie-Lab Nguyen, via Wikimedia Commons.


Ethics is one of the most central disciplines of philosophy. Ethics can simply be defined as a moral philosophy, as it’s concerned with what is morally good and bad, or morally right and wrong. We can also define it as the study of the righteous and virtuous way of living. It’s the study of how man should live his life to be in accordance with what is allowed and what isn’t. It’s a branch of philosophy that teaches us how to be in harmony with nature and our surroundings.


Lots of philosophers have given their thoughts on how to live the best possible life. Aristotle based his ethics on the virtue of the “golden mean” as the highest human value. He says that man has to live his life in accordance with the golden mean – nothing too much, and nothing too little. For example, modesty is the golden mean between selfishness and extreme generosity.


Epicurus believed that the role of ethics is to help men with their mental struggles. The goal of ethics is a happy human life. In order to do that, Epicurus says that we have to let go of all of our fears, so that we can lead a happy and purposeful life.


Virtue and Humility by A. N. Mironov, 2018, via Wikimedia Commons.


Ethics is a very valuable field of study not just in philosophy, but in science in general. It teaches man how to act and behave, and as such, helps him to become an autonomous human being.


There are three major areas of study within ethics:


  1. Meta-ethics: the study of the nature, scope, and meaning of moral statements.
  2. Normative ethics: the study of the practical means of determining a moral course of action. Normative ethics addresses questions such as “What should be done?”
  3. Applied ethics: its focus is what a person is obligated (or permitted) to do in a certain specific, real-world situation.


5. Examining Beauty: Aesthetics

Immanuel Kant by Johann Gottlieb Becker, 1768, via Wikimedia Commons.


Aesthetics is another important branch of philosophy. It can simply be defined as the study of beauty, taste, and art. It examines aesthetic values and deals with such notions as the beautiful, the ugly, the sublime, and so on. It’s a way of establishing the meaning and validity of critical judgments concerning works of art. We can also stumble upon the definition that it’s a study of the mind in relation to the sense of beauty.


Aesthetics has been around since the ancient period, and various approaches have been proposed throughout the years. Some philosophers thought that beauty is objective and universal and that there are certain standards a piece of art should possess in order to be considered beautiful. Other philosophers saw beauty as something that is subjective and relative, and that beauty is in the eye of the beholder. Hence, the reason everyone has a concept of beauty of their own, and the reason why someone might think of something as beautiful, while others may see it as ugly.


Flowers by Andy Warhol, 1964, via MoMA.


Another aspect of examination in the field of aesthetics is the definition of what art really is. Can nature be considered art, or is it only artificial, i.e., man-made pieces that represent art? If it’s only the man-made pieces that are art, does that mean that every artifact made by man is art? What standards should a piece of art possess in order for it to be considered an artistic piece?


In regard to these questions, there are various approaches. We will only give an example here. Some say that it’s the piece’s ability to imitate that contributes to the piece becoming an artwork. For example, painting nature on a canvas is a representation and imitation of reality. Thus, a painting of nature can indeed be considered an artwork, as it imitates something from the real world. Therefore, it’s this imitating ability that becomes the definitive property of the artwork.


Overview of the Branches of Philosophy

Portrait of Bertrand Russell, 1957, via National Archives of the Netherlands.


The disciplines mentioned above constitute what is widely known as traditional philosophy. They’re the branches that have defined philosophy since its starting point in ancient Greece, and they have been around ever since. It’s also worth mentioning that these are not the only branches of philosophy. That’s why it’s important to mention other relatively new disciplines: the history of philosophy, the philosophy of history, political philosophy, the philosophy of religion, the philosophy of language, the philosophy of law, the philosophy of science, and many more.

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By Antonio PanovskiBA PhilosophyAntonio holds a BA in Philosophy from SS. Cyril and Methodius University in Skopje, North Macedonia. His main areas of interest are contemporary, as well as analytic philosophy, with a special focus on the epistemological aspect of them, although he’s currently thoroughly examining the philosophy of science. Besides writing, he loves cinema, music, and traveling.