Can We Know What We Don't Yet Know? The Strange Philosophy of Fakhr al-Din al-Razi

Imagine you’re trying to solve a puzzle, but you have no idea what the puzzle looks like or what the answer should be. How would you even begin? Now imagine you do know what the answer should be. Then why are you bothering to solve the puzzle? You already know the answer.

This is not just a problem about puzzles. It’s a problem about learning anything at all. If you don’t know something, how can you search for it? You wouldn’t recognize it if you found it. But if you already know it, there’s nothing to learn. This is called the “paradox of inquiry,” and it was first noticed by a philosopher named Plato about 2,400 years ago. But a man named Fakhr al-Din al-Razi (let’s call him Razi for short) took this puzzle very seriously, and it led him to some strange conclusions about knowledge, God, and even whether we have free will.

Razi was born in 1149 in what is now Iran. He grew up studying Islamic theology and law with his father, but he also read the works of the most famous philosopher of the Islamic world—a man named Ibn Sina (known in the West as Avicenna). Razi spent his whole life arguing with Ibn Sina’s ideas, sometimes agreeing, sometimes disagreeing, but always taking them seriously. He traveled across central Asia looking for intellectual opponents to debate, and he wrote enormous books—one of them is 32 volumes long. He died in 1210, a few decades before the Mongols swept through and destroyed much of the world he knew.

Here’s what’s strange about Razi: he didn’t just want to defend one side or the other. He wanted to consider every possible position on every question, even positions nobody had ever actually held. He would lay out arguments for and against each view, and sometimes he wouldn’t even tell you which one he thought was right. He’d just say “God knows best” and move on. This drove some later readers crazy. But it also made him one of the most interesting philosophers you’ve never heard of.

The Puzzle of How We Know Anything

Let’s go back to that paradox of inquiry. Razi was convinced that the standard answer—that you can know something in one way and learn something new about it in another way—doesn’t actually solve the problem. He thought it just pushes the problem down one level. If you don’t know what the parts of something are, how do you search for them? And if you do know, you’re done.

So Razi came to a surprising conclusion: we don’t actually learn things by searching for them. Knowledge just happens to us. When you look at a red apple, you don’t decide to see it as red. You just do. The redness is forced on you. The same thing happens when you think about what a “human” is. You don’t figure it out by building a definition piece by piece. You just have the concept, or you don’t.

This might sound like a weird technical point, but it has big consequences. For one thing, it means we don’t really have control over what we believe. If your friend tries to convince you that the sky is green, you can’t just decide to believe them. You see it’s blue, and that’s that. For Razi, all knowledge works this way. It’s all given to us—and in his view, given directly by God. This is part of a system called “occasionalism”: the idea that God is constantly creating everything, including our thoughts and perceptions, at every moment.

Is the World Made of Tiny Bits?

Now, if you’re someone who thinks God is constantly making everything happen, you might also think the world is made of tiny, indivisible parts—atoms. This was the view of many Islamic theologians in Razi’s time. They thought that bodies are made up of atoms so small they can’t be divided further, and that God is constantly re-creating these atoms from moment to moment. (This is very different from the atoms of modern science, which can be split.)

But Ibn Sina had argued against atomism. He thought matter is continuous—any part of any body, no matter how tiny, can in principle be divided further. Razi wrestled with this question for his whole career. In some books he seemed to reject atomism; in others he accepted it. By the end of his life, he came down on the side of the atomists. Here’s one of his arguments: take a sphere—a perfect ball—and roll it across a flat surface. As it rolls, it touches the surface at a series of single points. Those points must be indivisible, because if they had parts, the ball would be touching the surface at multiple spots at once, which doesn’t make sense. Therefore, there must be indivisible points—atoms.

If you believe in atoms, you might also believe in empty space (a “void”). If the world is made of tiny particles, there must be gaps between them where there’s nothing. Razi argued that void is real. Think about pulling two flat surfaces apart. For a tiny moment, there’s nothing between them—then air rushes in to fill the gap. That moment shows that void exists, even if only for an instant.

What Does It Mean for Something to Exist?

This brings us to the deepest question Razi explored: what does it mean for something to exist? We tend to think that “being a red apple” and “existing” are the same thing—the apple just is. But Ibn Sina had pointed out that they’re different. You can think of a red apple without knowing whether it exists. The “what it is” (its essence) is different from the “that it is” (its existence).

Razi agreed, but he pushed the idea further. He thought essences—the “what it is” of things—are somehow prior to existence. The essence of a red apple is there, in some strange way, before the apple actually exists. This doesn’t mean there are ghost-apples floating around. It means that when God creates an apple, He’s taking the idea of “apple” and adding existence to it. For regular things, this combination is fragile—the apple could fail to exist. But for God Himself, His essence is so powerful that it forces existence. God necessarily exists because of what He is.

This leads to a radical conclusion. For Ibn Sina, God was special because His existence was a different kind of existence—more intense, more perfect. But Razi said no. Existence is the same for everything. What makes God special is His essence, not a special kind of existing. This is incredibly similar to an idea developed about a hundred years later by the European philosopher Duns Scotus, who probably never even heard of Razi. Sometimes great minds think alike, even when they’re half a world apart.

Does God Know What You’re Doing Right Now?

Here’s another problem Razi tackled. If God is perfect and doesn’t change, how can He know what’s happening right now? After all, in five seconds you’ll be reading a different sentence. If God knows that you’re reading this sentence now, then in five seconds He’ll have to stop knowing that and start knowing that you’re reading something else. That sounds like a change—which would mean God isn’t perfect and unchanging.

Ibn Sina’s solution was to say that God only knows universal rules, not particular events. God knows the laws of nature and causation, but He doesn’t know which specific things are happening at each moment. This preserves God’s unchanging nature, but it also means God doesn’t really know you as an individual.

Razi found this unacceptable. His solution was clever: knowledge, he said, is a relation between the knower and what’s known. If you stand still and watch a parade go by, you don’t change—the parade does. Your relation to the parade changes, but you stay the same. Similarly, God doesn’t change when events happen. The events pass by, and God’s relation to them changes, but God Himself remains exactly the same.

This might sound like wordplay, but it connects to something deep about how we think about minds. Normally, we think that when you know something, the thing you know somehow gets “into” your mind—like an impression in wax. Razi rejected this. For him, knowing is just a direct relationship to the thing itself, not having a copy of it in your head. This means that when you think about a phoenix—a bird that doesn’t exist—you’re not thinking about a “mental phoenix” that exists in your mind. You’re just combining ideas of things that do exist (a bird, fire, etc.) in a way that doesn’t correspond to reality.

Are Humans Really So Special?

We tend to think that humans are completely different from animals. Animals have instincts and feelings, but only humans have reason. Razi wasn’t so sure. He thought the human soul is a single, unified thing—not a collection of different “faculties” (one for seeing, one for thinking, one for remembering, etc.). And if the soul is unified, then the same thing that sees a red apple also thinks about what “redness” means.

But Razi went further. He argued that animals also have what looks like intelligence. They’re self-aware. They remember things. They solve problems. They make plans. They recognize that they persist through time. In his late work, he says outright: if “reason” means having intelligence, then animals have reason. This doesn’t mean all animals are as smart as humans—there’s a spectrum. But the sharp line humans like to draw between themselves and other animals is probably an illusion.

What Should We Do, and Can We Choose?

Finally, Razi had a lot to say about ethics—how we should live. He was part of a tradition that said right and wrong are determined by God’s commands. But he added a twist: he was also a hedonist, meaning he thought pleasure is good and pain is bad. These two ideas combine: God commands us to do things, and He promises pleasure if we obey and pain if we don’t. So following God’s commands turns out to be the smart, self-interested thing to do.

But what if there’s no clear command from God? Then, Razi says, we should do whatever maximizes pleasure and minimizes pain for everyone. Not because we’re nice, but because it would be better for us if everyone acted that way. This is very close to what modern philosophers call “rule utilitarianism.”

Here’s the catch: Razi also thought we don’t really have free will. Remember, he believed our beliefs and perceptions are forced on us by God. But he also thought our actions are forced on us by our beliefs, motivations, and abilities. If you believe something is good, and you have the ability to do it, you will do it—you have no choice. So even though Razi tells us to pursue pleasure and avoid pain, he also thinks we can’t help but do exactly that. The advice is more like describing how the world works than giving us options.

Why Does Any of This Matter?

Razi died more than 800 years ago, and many of his books are not even translated into English. So why should a 12-year-old care about him?

Because Razi shows us something important about how to think. He didn’t just defend one side. He considered every possible view, even ones he disagreed with. He was willing to follow arguments wherever they led, even if they led to uncomfortable conclusions (like that we don’t have free will, or that animals are smarter than we think). And sometimes, at the end of a very long argument, he’d admit he didn’t have the answer.

That takes courage. It’s easier to pick a side and stick with it. Razi chose the harder path: looking at every argument from every angle, and sometimes admitting he didn’t know. That’s a model for how to think about anything—not just philosophy, but science, politics, games, and arguments with your friends. The goal isn’t to always be right. It’s to understand the problem from every possible side.

Key Terms

Term	What it does in this debate
Essence	The “what it is” of something—what makes a human a human, or an apple an apple, apart from whether it actually exists
Existence	The “that it is” of something—the fact that something is real, not just a concept in your mind
Atomism	The theory that matter is made of tiny, indivisible particles (atoms), which Razi eventually accepted
Occasionalism	The idea that God directly creates every event, including our thoughts and perceptions, at every moment
Paradox of inquiry	The puzzle: if you don’t know something, you can’t search for it; if you do know it, there’s nothing to search for
Divine command theory	The view that right and wrong are determined by what God commands, not by any independent standard
Hedonism	The view that pleasure is good and pain is bad, which Razi used as the foundation of his ethics
Void	Empty space—space with nothing in it, which Razi believed actually exists

Key People

Fakhr al-Din al-Razi (1149–1210): A Persian philosopher and theologian who spent his life writing enormous books that considered every possible argument on every question, often without settling on a final answer.
Ibn Sina (Avicenna) (980–1037): The most famous philosopher of the Islamic world, whose ideas about existence, God, and the soul Razi spent his whole career arguing with—sometimes agreeing, sometimes disagreeing.
Abu l-Barakat al-Baghdadi (died 1160s): An earlier philosopher who influenced Razi’s views on the unity of the soul, the nature of time, and God’s knowledge of particular events.
Plato (428–348 BCE): An ancient Greek philosopher who first noticed the paradox of inquiry (the puzzle about how we can learn anything new) that Razi took so seriously.

Things to Think About

If Razi is right that we can’t control what we believe (because knowledge is forced on us), does that mean we shouldn’t be blamed for having wrong beliefs? Or does it mean there’s no such thing as “wrong” beliefs at all?
Razi thought animals have reason, just less of it than humans. What would follow from this? Should we treat animals differently if they can think and plan and remember? Where would you draw the line?
If pleasure is the only thing that’s good, and God commands us to do things because they lead to pleasure, does that mean God is just maximizing His own pleasure? Is there a difference between “doing good because it’s right” and “doing good because it makes you feel good”?
Razi’s method was to consider every possible argument, even arguments he didn’t agree with. Is this a good way to think? Could it be dangerous—could it give bad ideas more attention than they deserve?

Where This Shows Up

Debates about free will and determinism are still happening today in philosophy, neuroscience, and law. Razi’s arguments—that our beliefs and actions are forced on us—are very similar to arguments modern scientists make about how the brain works.
The problem of divine knowledge (how an unchanging God can know changing events) is still discussed in philosophy of religion. Razi’s solution—that knowledge is a relation, not a change in the knower—is still a live option.
Animal intelligence is a hot topic in science right now. Razi’s view that animals have reason, and that there’s a continuum between human and animal minds, fits well with current research on animal cognition.
Atomism and the void—These ideas, which Razi debated in the 12th century, are central to modern physics. The question of whether space is empty or filled with something is still not fully settled.