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Modern Categorization of Thought: the 3 Branches of Philosophy

Updated: Aug 24

By trying to understand our thoughts, we are trying to understand ourselves.
The three branches of philosophy are metaphysics (What is reality?), epistemology (How do we know reality?), and ethics (What do we do with reality?)

By trying to understand our thoughts, we are trying to understand ourselves. That’s why knowing the branches of philosophy and what they state is so crucial. In this postmodern era of social media apps, short attention spans, and increasing apathy, losing interest in the art and science of careful reflection and inquiry (also known as philosophy) is missing out on nearly three thousand years of self- and societal- improvement, and is in a sense a losing of ourselves - or, at least, a potential of what we can be!

"The love of Sophia giving birth to science and technology" | AI art via MidJourney by Steve Ross

Sure, we enjoy the rendering of philosophy in the form of science and tech (philosophy led to the creation of both those things), but if we don’t harness the source of those byproducts (the source being “friends with wisdom”) then we miss out on that creative and life-giving impetus for ourselves. What other distinctive aspects of man like science and technology can philosophy render for us today?

Steam engine used in Hellenistic Alexandria before the Industrial Revolution. The Greeks used their philosophy to create science and then technology, the Romans capitalized this for their engineering, and the Renaissance brought it all back for the modernity which we live in today. | Image via

Furthermore, why let other philosophers have all the fun? As we have noted earlier, anyone can do philosophy. All you need is wonder! All you need is a child-like mind to turn things over in your head and ask the basic questions of “Why?”

So, how do we categorize nearly three millennia of these questions as a starting point for questions of our own? Or maybe other philosophers have asked questions that we ourselves have asked before, and maybe their answers are some that we can take up and use for ourselves for the time being?

What classification method has been used so far that we can enjoy today?

To Categorize to Understand

Aristotle is the one who truly started placing different notions and physical objects into categories in order for us to understand them and study them more. The entire scientific classification of organisms that students and biologists use today is owed to him. But, what are the modern groupings of philosophical questions? What do the branches of that tree look like?

A chart showing how Aristotle placed organisms into plant categories and animal categories.
Aristotle's Classification of Living Things via

Though they have developed over time and sometimes in overlap with each other, the three branches of philosophical discussion as we survey the past 2,600 years on the matter can be listed as the following: metaphysics, epistemology, and ethics. Each one deals with its own unique inquiry.

As I word it, metaphysics wrestles with the question, “What is reality?”, while epistemology wrestles with, “How do we know reality?” Finally, ethics seeks to put it all together and find the practical meaning of it all by addressing, “What do we do with reality?”


After Aristotle wrote a series of books on the nature of mutability and immutability, an editor shortly afterwards labeled one group of works “Physics” and another group of works “Metaphysics” - the former regarding things that change and the latter regarding things that do not change. Meta means “after” in ancient Greek; so the moniker “After Physics” was actually appropriate being that this body of work did come after the work of “Physics.” However, the ocean of thought that expanded under that moniker and under that name encompasses broader subjects of inquiry than what that ancient philosopher discussed in his books which bear said title.

Also, a metaphysician is not necessarily a New Age bookstore owner either. This type of metaphysics deals with something a little bit broader, more mainstream, and something regarding the everyday, and even the “purely rational.”

Metaphysics wants to answer the question, any question regarding, “What is reality?” In our Space and Information Age, it may seem as though such a philosophical inquiry is unneeded- since all that can be known is known [insert sarcasm.] But, although science continues to emerge, there are many questions that are still unanswered. Questions like these:

  • What is the fundamental nature of reality?

  • Are some things “more real” than others?

  • Could the quantum realm help explain spiritual experiences?

  • Does God exist?

  • Are we inside someone else’s mind?

  • Could another universe be inside my mind?

  • When does personhood commence for the individual human being?

  • Is the future just as concrete as the past?

  • How many prosthetics can a person get before he is not a person anymore? (This goes into “transhumanism” or technological integration in general including the ever-increasing reliance on apps and AI.)

  • How many transplants can a person get before he is not the same person anymore?

  • What is the difference between artificial life and real life?

  • Can AI become a person?

  • Is 3D-printed biomass the same thing as naturally rendered biomass?

  • Is there some type of life force that somehow gains a presence in the world?

  • How synthetic can a biomass be before the life force does not attach itself to it?

  • Can AI become gods?

  • Does the way in which an entity processes information categorize it as life or non-life?

  • What is the appropriate language for God or to describe God?

  • Is man just animals and animals just machines?

  • If all is just machines, what is the meaning to life?

  • Can meaning in life be found more in being or more in doing?

  • What was before the universe that we know and measure today?

  • Are other universes possible? If so, what possible natures could they have?

numbers and mysterious math symbols collectively floating together like a tunnel through space and time.
Mathmatical platonism: numbers existing both independently of and in connection with space and time | AI art via MidJourney by Steve Ross
  • What is the proper nature of numbers? (Are they real and independent of space and time, are they real in the sense that they’re a concept and a “story” of space and time but are non-abstract in nature, or are they truly both non-abstract and not true or real even though we find them to be useful in space and time?) How “real” are numbers or math in general?

  • Is there an end to the relationship of a circles’ circumference to its diameter also known as pi (3.141592…)?

  • What is love?


First coined in 1854 by Scottish philosopher Jamer Ferrier, “epistemology” covers a realm of thought that goes back millenia. Etymologically, the term conjoins the meanings of “knowledge” (episteme) and “the study of” (logos). The most famous of the epistemological philosophers and certainly the most influential in our time is Rene Descarte who wrote in 1641 what the script of the Matrix would have been based on in 1999.

Image of Rene Descartes next to an image of an early copy of Meditations.
Deductive reasoning and Western individualism go back largely to Descartes' statement in his Meditations, "I think, therefore I am." | Image via

Descarte poked and prodded at the nature of reality and more pointedly our understanding of it by thinking about the question, “How do I know that I exist?” No matter what answer he threw at that question he was left unsatisfied until he devised the answer, “I think, therefore I am.” Put in another way, “How can I know that I exist?....Well, if I don’t exist, then I couldn’t even think about such a question. I know I must exist, because I think!” This philosophical thought process, recorded in the Meditations, assuaged his theological angst on whether he could accidentally stop believing in the true God of heaven and earth. But this answer also ushered in an age of Enlightenmentarian philosophy, the Industrial Revolution, and the Space Age.

Struggling with the ultimate question, “How do we know reality?”, epistemology also encompasses inquiries like the following:

  • How do you know that you know what you think you know?

  • Are there some things we cannot know?

  • How do we know what the limits of our knowledge are without knowing what is on the other side of those limits?

  • What is the best way to sift reliable knowledge from unreliable knowledge?

  • How do I know that I exist? (Can I trust my senses?)

  • Am I dreaming right now? What if I am inside someone else’s dream? How would I know?

  • Can I get information outside of the five physical senses?

  • How do I know that I am living a balanced life?

  • Are feelings the ultimate barometer of awareness?

  • Can the human consciousness speak with and be aware of God?

  • Is it possible to know when a civilization, a movement, or a relationship has reached its zenith? Is it possible to know warning signs of its decline?

AI art of six verticle cosmic paintings.
"All dimensions of the universe" | AI art via Midjourney by Steve Ross | Metaphysics posits that there may be multiple dimensions beyond our physical capabilities of sensing them. Epistemology explores our ability to know these things without the aid of said senses. Can there be realms that are beyond our ability to read or sense? And if so, how deep is that expanse?
  • How much math regarding physics can we trust where scientific technology currently falls short [for example, theoretical physics deals with things too big (hyperspace) or too small (superstrings) for our current scientific instruments to measure yet the math suggests may be there].

  • How do we know when a regularity that we see in nature is a meaningful pattern and not a case of pareidolia or coincidence?

  • Is the mind of a human truly capable of comprehending all types of math or physics that can exist?

  • Is there a knowable end of pi?

  • How do you know you’re in love?


Although ethics and morals are used interchangeably in common parlance, the two actually have distinct definitions and usages in philosophy. In our course of study, the term ethics regards the systematic structure behind how we think about morals. Whereas the term morals regards the actual behavior and specific manifestations of ethics in the day to day.

In short, morals are more practical (tractionable and action-oriented) and ethics is more philosophical (it’s discussion-oriented and abstract…therefore, perhaps a little bit easier to talk about.) Morals are something that we have to live out day-to-day whether if we think about them or not. Ethics can be left unfinished, in mid-conversation, and no one would get failed for it!

All in all, ethics regards the inquiry, “What do we do with reality?” Here are some examples of ethical questions:

  • What is the right way to live?

  • How do we construct rules for living without being too rigid?

  • How do we construct rules for living without being too flexible?

  • What is the best way to structure society?

  • What is the best way to preserve civil society?

  • How much can we influence society regarding right behavior without our becoming tyrannical or violating other people’s rights to behave how they see fit?

  • How much should be “live and let live” without becoming negligent of societal responsibility?

  • Is it possible to have a tolerant society without becoming intolerant of the “intolerant”? (c.f., Karl Popper’s “Paradox of Tolerance”.)

A cover of Plato's Republic and a copy of the U.S. Constitution
The top-down, authoritarianism in Plato's Republic verses the amendable Constitution written by the Framers and ratified by the States | What is the greatest way to organize ourselves is a topic of ethics | Images via Penguin Classics and Getty Images
  • Theoretically, the state “withers away” in both a Marxist utopia (where the state forces society into perfection) and, what I call, an “enlightened anarchy” (where civil society outgrows the need for the state). If the need for civil governance of any form can be truly outgrown and done away with, in which scenario is this most likely to happen?

  • What ought to be the goal of human life: happiness, fulfillment, service?

  • Can we approach ethics without religion?

  • Can we approach ethics without experience?

  • Is morality like math? (Euclidean geometry or general relativity?)

  • What is a good type of love? Can there ever be a bad type of love?

  • What is the right forum in which to talk about love, its boundaries, and its permissible forms?

  • Is change as reform the same thing as change for change’s sake?

  • To what degree should civil government reflect the culture of the people it is entrusted to represent?

  • Do the tradeoffs of the death penalty as a deterrent outweigh the undeniable possibility of wrongful execution of justice in outlying cases? In which less-than-ideal system of justice can society benefit the most?


So, which bucket of philosophical thought do you want to explore first? Which one do you resonate with most? Is it the nature of reality, the nature of knowledge, or the nature of morality? Structuring thought is important in order to better understand it and interact with it more. Maybe a new branch of philosophical thought can emerge; but for now we have our hands full already with metaphysics, epistemology, and ethics!

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