The first period of philosophy concerned nature and the cosmos. The second period turned to knowledge itself, and to ethics and politics.

After a hundred and fifty years of debate yielding various contradictory yet reasonable views, people began to doubt human knowledge itself. Meanwhile, as the Greeks expanded outward and colonized new lands, they encountered foreign peoples with vastly different customs and ways of life.

All of this led the Greeks to ask two questions:

1. Can humans truly acquire certain knowledge? 2. Is there a universally valid moral and political ideal—something that holds true everywhere?

These two questions are connected: if people cannot obtain certain knowledge, if those holding completely different views are all equally correct, then on what grounds can we demand that others follow our ways, that people with different customs obey our laws?

(I) The Sophists

First to take the stage were the Sophists, who offered these representative answers to the questions above:

1. Skepticism (Gorgias)

Nothing exists; even if something exists, you cannot know it; even if you can know it, you cannot communicate this knowledge to others.

Gorgias could be called the ancestor of all nitpickers. Whatever definite view you hold, he’ll keep asking “why?” If you heard it from someone else, how do you know you grasped their original meaning? That’s the problem of whether knowledge can be shared. If you observed it yourself, how do you know your perception matches reality? That’s the problem of whether existence can be known. And even if your perception is sound, how do you prove the thing actually exists and isn’t just your imagination? That’s the problem of whether anything exists at all.

If Gorgias only asked questions without stating views, he’d be hard to refute. The answers require generations of effort to develop. But by stating his own position clearly, he also gave others something to attack: if everything you say is true, how did you arrive at this very claim? And how are you communicating it to us?

2. Relativism (Thrasymachus): Justice is the advantage of the stronger.

Justice represents the interest of the strongest. Anyone holding other views is naive and childish.

In today’s world where social Darwinism thrives, this has become gospel truth for many. “Political power grows out of the barrel of a gun.” “Might makes right.” And so forth.

3. Perspectivism (Protagoras): Man is the measure of all things.

“Man is the measure of all things” admits multiple interpretations. From an epistemological angle, it can mean: things never show themselves as they truly are; they always present themselves from a human perspective, revealing only one facet. A brick is building material to a construction worker, a weapon to a thug. We are all blind men touching an elephant—each can only grasp the part before him. Since everyone’s understanding is based on their own perspective, are all views equally valid? Or is there no such thing as right and wrong anymore? But then how do we know everyone’s talking about the same brick, touching the same elephant? Is it because perspectives can shift and overlap?

For concrete objects, we can freely switch perspectives. But when we turn to society, when switching perspectives becomes as hard as switching class positions, can we even communicate anymore? Just as a rural farmer can’t imagine whether the emperor uses a gold hoe or silver hoe, urban residents can’t fathom how six hundred million people live on a thousand yuan a month. And it’s not just class—gender, race, age, education, intelligence all create similar gaps. Human joys and sorrows do not connect. If we insist perspectives are absolute, communication between groups and individuals becomes impossible. The very foundation for rational political discourse vanishes—so how can we speak of universally valid moral and political ideals?

From a normative angle, “man is the measure of all things” can also mean that the value and meaning of phenomena are relative to humans. Things themselves are neither good nor evil; good and evil are relative to individuals or groups. Good and evil are human constructs. So who ultimately gets to set the standard for good and evil? If individuals are the standard, we run into the previous problem—losing the foundation for rational political discourse. If society is the ultimate judge of normative questions, does that mean values and norms are valid only for the society that produced them, and inapplicable elsewhere? Laws that work for Greece don’t work for Persia; systems that work for Europe and America cannot work for China?

These three positions remain remarkably resilient even today. But fundamentally, Sophist views are demoralizing. Skepticism denies from the ground up that humans can obtain certain knowledge. Relativism denies that people can rationally build good societies. Insisting on absolute perspectives inevitably fragments and scatters people’s hearts. Yet politics and law demand unified opinions and actions. So the Sophists gradually lost public support. Someone had to stand up and refute them, or civilization couldn’t go on.

(II) Socrates: Virtue is Knowledge

Enter the great Socrates. How did he refute the Sophists? He affirmed the existence of universal good and justice. His famous saying: Virtue is knowledge.

In his view, human virtue lies in fully realizing one’s true potential. For him, knowledge isn’t just empirical facts—it includes normative knowledge about good and evil, and ultimately knowledge of the self: “Know thyself.”

Socrates believed virtue is knowledge, and can be learned. Right knowledge leads to right action. If you truly grasp justice, you’ll necessarily act justly, which makes you a just person. And right action necessarily produces happiness. Those people who “understand many great truths yet still can’t live well” don’t exist in Socrates’s world—that just means you’ve picked up scattered opinions from others without truly grasping and integrating the underlying principles. Socrates’s notion of happiness encompasses more than ordinary worldly happiness; it’s closer to inner peace, wholeness of character.

(III) Plato: The Theory of Forms

Socrates held that we can learn to recognize norms like good and justice. But what exactly are these norms? Do they exist objectively? Or only in our minds?

Why does this matter so much? It connects directly to our opening question—is there universal law? If Forms exist objectively, then whether you’re in Greece or Persia, East or West, as long as people use reason to investigate, they’ll eventually reach the same destination—discovering the universally and objectively existing “Good” and “Justice.” And then the theoretical foundation for world unity becomes rock-solid.

Plato’s Theory of Forms is exactly such a theory: The universe divides into two realms—the realm of Forms and the realm of sensible things. Forms can’t be grasped through the senses, only understood through reason. Like mathematical circles and triangles, these perfect concepts don’t exist in the physical world. Reality contains only approximations—things in the world are transient, changeable manifestations of these concepts. Compared to fleeting appearances, the Forms themselves are universal and unchanging. They don’t exist merely in our minds; they exist objectively and hold universally.

Corresponding to the Theory of Forms, Plato’s political vision is his Republic. Forms exist objectively, but people’s capacity to know them varies—that’s the reality. Forms are difficult to understand; acquiring knowledge of Forms requires good intelligence and training. The inevitable result is that the few who can perceive Forms and possess virtue must guide the many down the right path.

Because of Socrates’s death, Plato came to despise Athenian democracy, believing power should rest with those competent to wield it. He advocated establishing a universal education system where after years of study and training—learning both knowledge and practical experience, and learning to perceive the Form of the Good—”philosopher-kings” would be cultivated and selected to rule the state.

(IV) Aristotle

Aristotle, though Plato’s devoted student, had a famous line: “I love my teacher, but I love truth more.” True to these words, Aristotle opposed his teacher on many fronts.

Plato wanted to transcend existing order to pursue ideal order; Aristotle sought the best order within what exists. Plato believed only Forms truly exist; Aristotle said individual concrete things (substances) exist independently, while abstract concepts like attributes and categories exist only relatively—as abstract forms within concrete phenomena. For Plato, sensory experience is imperfect knowledge; true knowledge lies in perceiving Forms. For Aristotle, sensory experience is more real. What we can do is use reason to extract universal forms from particular things.

What particularly strikes me is Aristotle’s conclusion after he and his students collected material on 158 Greek city-states, classified and extensively discussed them:

Limited democracy is the best polity we can hope for. The state should be governed by law, democratic in quantity, aristocratic in quality. Politics based on law ensures everyone is free and many have a voice. Neither the rich nor the poor, but the middle class, has the greatest strength. Government members numerous enough to cover public opinion, yet few enough to ensure political transparency. This polity achieves the best balance between public opinion and wise governance. More importantly, this is the most feasible polity.

I’m amazed—because two thousand years later, the world hasn’t surpassed Aristotle’s conclusions. America, Britain, Germany, Japan—every effective, well-functioning government in the world embodies principles from Aristotle’s vision. As of now, I’m with Aristotle.

That concludes our discussion of ethics and politics for now. The question “Is there universal law?” remains open—we’ll keep exploring it in future installments.