The Fundamental Principles of Human Understanding

The Greeks, Kant, Hume, Locke, Kierkegaard and the Spheres of Human Understanding: Logic, Physics, Ethics, Metaphysics

All knowledge, all human understanding, can be said to be of four types: physical (empirical), logical (reason), ethical (philosophy in-action), and metaphysical (pure philosophy).

The Greeks, Kant, Hume, Locke, and others including in some ways Kierkegaard all agree that the core three expressed by the Greeks, that is Logic, Physics, and Ethics, are generally suitable to any good theory of human understanding.

However, Kant [essentially] argues for a fourth term in his master work Fundamental Principles of the Metaphysic of Morals, the Aristotelian term metaphysics (which contains knowledge that is “pure philosophy”).

From that we can create a simple model of the “four fundamental principles of human understanding”: physical (empirical, what is), logical (reason, logic-and-ethics in-thought), ethical (morals-and-ethics in-action), and metaphysical (pure metaphysic morals, or pure philosophy, what should be).

Great, so all knowledge should be able to fit in that model and thus it should work as a general metaphor for all walks of life, especially the social sciences and philosophies where things get a little ethereal (but were categorization and models are needed none-the-less; like with the political left-right).

We can summarize all the above to say: Natural Philosophy contains physics (here understood as all physical things, not Newton’s physics) and logic (pure reason like the pure practical reason of mathematics and theoretical physics) and Moral Philosophy contains ethics (like a lawyer’s rule-set) and metaphysics (the potentially unprovable pure morals behind the lawyer’s rules; pure philosophy).

Below we have taken this basic concept presented above and worked it into models and modernized definitions beyond just an ordered list. The primary goal won’t be to prove we can have knowledge of metaphysics (the most prickly concept here, as it has been long known), rather it will be to offer useful models and toolsets for those who want to explore the different spheres.

A justification for considering metaphysics: The reality is, our forefathers from the Greeks to the Enlightenment thinkers have already worked out how to explain the world with only physics, logic, ethics… still, I think it is important that we not forget metaphysics, despite its frustrations (less we all “unbalance the scales”). We don’t ignore dark matter just because we can’t prove it, we don’t ignore quantum physics just because it is ruled by odd probabilistic laws, why ignore metaphysics?

An Introduction into the Spheres of Knowledge and Some Core Principles of Human Understanding

Each of the spheres of human understanding (which from here forth we’ll simply call physics, logic, ethics, and metaphysics) is unique (if it wasn’t, it wouldn’t be a different “sphere”).

The empirical is easiest to confirm (as we sense it directly). This is the preferred knowledge type and the core of most knowledge from Lockean principals to those of the Scientific Method.

Next comes logic, things like F=ma or 1+1=2. Those facts aren’t as tangible (if they were they would be empirical), but they are confirmable. We constantly use reason, symbols, and other logic in practice, so we can feel pretty comfortable with this one.

The simplest example of proving logic is a type of knowledge is that F=ma is not empirical, but rather pure reason, yet any engineer can confirm this Newtonian principle with perfect accuracy with every structure they build). We can know force equals mass times acceleration indirectly via empirical data and testing… even though we can’t know it directly. In this same way, we can also know facts about ethics and metaphysics.

The ethical is harder to define, but we can see it in the way lawyers act, or the way a solider adheres to a code of honor, or to the way a King leads the charge into battle. To the extent that we have “ethical knowledge” (such as that contained in the Constitution), we can confirm this is a sphere of understanding (more on this later).

Lastly, the most ethereal, the metaphysical is the hardest to confirm knowledge of. It is the equivalent to trying to define empty space. What is it that drives our ethics? Is it logic or the purely physical? Can we confirm knowledge about morality empirically, or is this one sphere always going to remain ethereal? Those are all good questions.

We can seek to prove that we can have useful facts about of the types of knowledge by finding the places where the realms of knowledge “cross forks“, like we did with logic and empirical data with F=ma, and this will theoretically allow us to confirm aspects of the more elusive non-empirical ethics and metaphysics… but that subject is secondary to this introduction (especially given the history of moral philosophy, which shows us these questions are still generally unanswered and to what degree they are answered the answer is “we can’t prove facts about pure philosophy”).[1][2]

Understanding the Spheres of Human Understanding: Physics, Logic, Ethics, and Metaphysics

Without further ado, synthesizing all the above works, we can say these terms can reasonably be placed into a model like this.

Spheres Empirical (sphere of facts based on experience) Rational (sphere of facts about ideas)
Natural Philosophy (sphere of facts based on experience) Physics (Pure Empiricism) Logic (Pure Reason)
Moral Philosophy (sphere of facts about ideas) Ethics (Philosophy-in-Action) Metaphysics (Pure Philosophy)

This is to say:

  • Physics: Is that which is. It is detectable with the senses (or theoretically with measuring technologies). The study of the purely physical was once called naturally philosophy and now is called “the natural sciences” (i.e. not only Einstein‘s physics, but natural science; the knowledge of all things physical).
  • Logic: That which is, but is a thing of pure reason (it describes “what is”). It is not directly detectable with the senses, but it correlates perfectly with the physical. F=ma is pure logic, but it is also a simple equation that explains local gravity. 1+1=2, if it didn’t, computers wouldn’t work. These are logical rules that govern the physics. It is what we call theoretical science and mathematics, it is the logic of the physical.
  • Ethics: Is that which ought to be, applied to the physical (like when a judge or lawyer acts upon the law). It is what separates a human from reptiles. It is free-will, it is action. It is what we call ethics and law. All the practical moral sciences.
  • Metaphysics: Is that which ought to be, but is a thing of pure philosophy (it describes not “what is”, but what is behind that, the true nature of things). There is a reason the Greeks didn’t define this term, it is ethereal. But like Kant implies in his Foundation of the Metaphysics of Morals, this pure philosophy is important in the same way pure reason is important. Where pure reason tells us about physics, metaphysics tells us about ethics.

An example of the difference between ideas and experience: “All bachelors are unmarried” (idea) vs. “A bachelor is sitting in the chair” (experience). We know the bachelor is in the chair because we see him sitting there. We only know all bachelors are married because they are bachelors (we can’t go around confirming each of the world’s bachelors is unmarried via our senses). We know this logically because it is necessary for the sentence to be true, but it tells us nothing specifically about our world (it is a fact about an idea, not a fact about the world). It is redundant, what Hume calls a tautology. We don’t want to look for tautological proofs to prove facts about ideas, we want to look for testable Synthetic a priori: facts about ideas that are true even though we can’t confirm them directly. This is to say we want to 1. look for “Synthetic a priori” that we can 2. test and prove through indirect empirical evidence.

TIP: Note that “logically” one can make a case that we can’t confirm facts about pure philosophy empirically (even if we can have a metaphysical “Synthetic a priori”, we can’t prove it). This is the stance Kant takes, he doesn’t think we can create a discipline out of the metaphysical “Synthetic a priori” knowledge because it can’t be tested empirically, but he does believe that we can know facts about pure philosophy. I tend to think there should be some theoretical way to indirectly prove metaphysical “Synthetic a priori” knowledge (by crossing forks with ethics, logic, and physics)… but that is probably out of scope for this article.

Ex. We can empirically and logically show that the non-aggression principle is true, and from this we can construct ethical laws from the natural laws of self defense. However, one can’t prove empirically with certainty that “killing in self defense is correct”. Likewise, we can say that which does the greatest good for the most people and the least harm (utilitarianism) is grounded enough in reason to create an ethical moral first principle… but we can’t make the leap to saying, it is a fact: “the meaning of life is happiness“. These “moral” statements of pure philosophy aren’t so easily proven, but physics, logic, and ethics are enough to hold them up in court and the social contract (they are good and useful facts, but not empirically provable with certainty). We can use the concept of “fairness” liberally, but we can’t confirm it exactly. Still, we can argue that “knowledge of justice” is a useful “knowledge of pure philosophy”. Pure philosophy can contain “Synthetic a priori” (so to speak), but not empirically provable principles and propositions.

Shouldn’t metaphysics and physics be in the same category and logic and ethics? One would think that the relationships between these four should be that physics is the “what is” of facts and metaphysics “the what is” of ideas, and then ethics and logic are the intellectual (non-physical) aspects of these. But the relationship between the four isn’t a duality, it is a quadrality in balance. So Physics is what is, logic is what we know, ethics is action, and metaphysics is what we can know about the morality of that action. I’m very certain the above is the correct way to display things. That said, these are all terms created by Humans, the core of what they explain is more important than the names.

TIP: Kierkegaard’s three spheres (or “three stages of life”) are related to this theory. He categorizes human experiences regarding happiness as aesthetic, ethical, and religious. To equate that to this theory, physical pleasures are aesthetic, logical and ethical pleasures are ethical, and metaphysical pleasures are religious. See theories on happiness as the meaning of life.

TIP: Other aspects of this theory are worked out on our page on our “Western Classical Element Theory as a Metaphor” and our“Separation of Powers Metaphor”. See those pages as well. At some point i’ll attempt to combine all this, for now, the theory spans several pages.

The Elements of Government and the Spirit of the Laws

An infographic displaying a model for the separations of power (a related metaphor).

Understanding Kant, Hume, and Others Via the Above Theory

In the above chart, we can understand why Hume says physical pure empirical data is the only real truth.

Physics is the most factual, it is the only one that exists purely in the sphere of empirically confirmable facts (the physical world).

Likewise, we can understand why Hume assumed that pure logic could not tell us about the world.

We can also see why Kant was able to cross Hume’s fork and show that logic could tell us about the world (where F=ma most certainly tells us about the world even though we can’t touch it).

Those points are easy to get, it is having that same discussion about ethics and metaphysics that gets tricky (although both Kant and Hume attempt, rather successfully, to do this… they do not come away with as rock-solid answers as they do with physics and logic).

Here we can see that, theoretically and logically, what is true for physics and logic should be true for ethics and morals by some measures and impossible by others.

Morals should be able to tell us about ethics. That is, we should be able to construct “correct” ethical laws from moral metaphysics (rationally, given what we can do with physics and logic).

However, I think it is a bit more complicated. I think we need physics and logic as a foundation, and then from that point we can pair ethics and metaphysics to tell us facts about the world.

When we act with ethics, we effect the physical, AND we can use logic to create ethical laws based on physical results (as anyone with a law degree knows).

We can from just physics, logic, and ethics create laws like the non-aggression principle and utilitarianism, creating first principles of morality without ever discussing metaphysics! That is a neat parlor trick, for sure, and [as Hume eludes] infinitely useful for conveying moral ideas to non-philosophers… but it also implies that we can’t have knowledge about pure philosophy, and I don’t think that is correct and neither did Kant (indeed, I’ve rather said it is a whole sphere of knowledge).

So how can we know something about something that we can’t know directly? In some respects it is in the same way we can know facts about logic even though we can’t hold a logic in our hands.

These spheres intersect and react with each other (speaking metaphorically). So we wouldn’t be looking for facts about metaphysics in metaphysics, we would be looking to see the shadows dancing on the physical wall, we would be looking for the intersection to see where the forks cross.

A sphere by its definition is its own thing. If it was not partly its own thing, then it would not be a different sphere.

However, if the spheres did not intersect in any way, then there would be no pathway between them.

If pure metaphysic philosophical morals could tell us nothing about ethics, then our ethics would be based only on physics and logic.

But wait in this lies the answer, if the empirical and natural is a reflection of the moral in any way, then as any good empiricist like Locke or Hume knows, we have a workaround without ever having to get refer to Aquinas and his Divine laws.

We simply say, “that which is physics” tells us about the the ethical laws using reason (using logic).

Still, from this we can extrapolate, that that which we glean from the physical, logical, and ethical is a shadow of the metaphysic dancing on the cave wall. We know we can’t hold it in our hand directly, like an equation, so it shouldn’t be looked for in that way.

We may not be able to have testable certainty [more like probabilistic quantum quasi-certainty if anything] about “the metaphysics of morals”, but we can have good theories that work and we can have what we can generally call “facts about pure philosophy”. That is a little weaker than F=ma, but that is what one can expect from the purely incorporeal.

All around us sits empty space, it is there, it has properties, we can point to it with logic, but it is ethereal and uncertain. Metaphysics is like the empty space of human understanding. It is there, just hard to poke with a stick directly.

Finding all the place’s where the metaphysic fork does cross into other spheres is a tall order, but it gives us reason to state that:

All knowledge, all human understanding, can be placed in four groups: Physics, Logic, Ethics, and Metaphysics… with each type having its own complexities in terms of proving absolutes about what exactly we know.

Where we can be the most certain about physics, and via that empirical data we can confirm our logic, through our logic and physics we can begin to confirm aspect of ethics and metaphysics.

There are some known-unknowns and unknown-unknowns here… but this is about categorizing knowledge, not knowing everything that is or ought to be (confirm dark matter and empty space; and if there is still no metaphysical moral certainty, at that point we can talk; even physics has an opposite but true force, just like many of the standard model particles and interactions).

There is plenty of physics we still don’t know, to assume we would know all of metaphysics given its much more ethereal nature is a little optimistic. Not knowing something proves nothing, not knowing is where the desire for understanding comes from, it is not a logical argument for the non-existence of a thing. If morals weren’t “a thing”, if the only things that were mattered, why do people act morally, go to church, or dedicate their lives to principles that go beyond what is purely physical, logical, or rational. What is empathy? What is faith? etc. Religion isn’t pure metaphysics, but its core of spirituality is in its sphere (and the church itself and its doctrine is that which takes the metaphysic and brings it into the physical realm, using the symbols of logic no less).

NOTE: Given the metaphysical sphere is the most elusive, and thus the hardest to talk about or pin down, we can see how it is the easiest to forget. Probably one of the biggest vices of our modern liberal capitalist Republics is the general moving away from metaphysics (morality, faith, spirituality… religion). Having freedom of religion is vital, but freedom from spirituality is a bit more troublesome. A modern political argument might consider the physical, the logical, and perhaps even the ethical (typically in that order; with sometimes “ethics” being based more on physics and logic than its moral side, with “law” being almost a synonym for “the will of the stronger faction“)… but rarely does it consider the moral first. When we discuss healthcare, it is about dollars and sense, not the morality of healing the sick for example (see these comments). This problem is not so easily solved, and perhaps it is better not to solve it than try to solve with too heavy a hand (i.e. Church states aren’t the answer, at least not one’s that push a very specific doctrine… as philosophy requires liberty, as Hume says in his essays on Human Understanding). Still, it is worth noting as it directly pertains to this subject. Liberty, equality, laws, rights, and morality are mutually dependent subjects, like the spheres of human understanding, different, complicated, but undeniably linked.

MUSING: When I hear [er um, read] Aleksandr Solzhenitsyn say “Men have forgotten God”, I don’t take him to mean it literally (even if he did mean it literally), instead I believe it is best translated to “people have, in their satisfaction with our new way of life, forgotten the importance of the metaphysics of morals“. If we don’t have a moral compass guiding our ethics, then it is physics and logic that guide our ethics… that at best gives us a technocratic set of morals, and that isn’t I think what Locke and Mill were getting at. To the extent we can find morals using reason and empirical data, great, but we aren’t looking at physics and logic, we are looking at the shadows of the moral forms dancing on the cave wall. We all love us some Aristotle, but lets not totally forget Plato.


  1. Analytic / Synthetic Distinction – The possibility of metaphysics
  2. Kant’s Critique of Metaphysics

"The Spheres of Human Understanding" is tagged with: Elements, Epistemology, Ethics, Human Brain, Immanuel Kant, Metaphysics

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