Can We Ever Really Know the World?

Or: What Peter Auriol thought about seeing, dreaming, and the mind’s strange power

Here’s a strange experience you’ve probably had. You’re sitting in a car that’s stopped at a train crossing. The train rolls slowly past, and for a moment your brain tricks you: it feels like you’re moving, not the train. Or maybe you’ve spun around until you’re dizzy, then stopped—and the room kept spinning. Or you’ve stared at a bright light and then looked away, and for several seconds you could still see its ghost floating in the air.

These moments are weird. But if you stop and think about them, they raise an unsettling question. If your senses can get things this wrong—if they can show you movement that isn’t happening, or colors that aren’t there—then how can you ever trust them? How do you know what’s really there, versus what your mind is just making you think is there?

A philosopher named Peter Auriol (pronounced aw-ree-ohl) thought about this question about 700 years ago, and his answer was both brilliant and disturbing. He lived in France, was a Franciscan monk (the order that wore brown robes and took vows of poverty), and eventually became an archbishop. But before that, he spent years thinking about perception, knowledge, and the strange gap between what’s out there in the world and what’s in here in our minds. His ideas were so unusual that people argued about them for centuries.

Here’s what he came up with.

The Problem with Seeing

Picture this. You’re on a boat drifting down a river. You look at the trees on the shore, and for a moment it looks like the trees are moving backward and you’re standing still. You know the trees aren’t moving. But they appear to be moving. Your eyes are showing you something that isn’t true.

Now another one. Take a pencil and twirl it really fast in front of your face. You’ll see what looks like a faint circle or disk in the air where the pencil tip is spinning. But… there’s no circle there. The pencil is solid. The circle is an illusion created by your own vision.

Auriol collected examples like this—he had eight of them—and he used them to make a bold argument. He said that your senses don’t just passively receive information from the world, like a bucket catching rain. Instead, your senses are active. They do something to the things you perceive. They take whatever is out there—the trees, the pencil, the candle flame—and they put it into a special kind of existence called esse apparens (pronounced ESS-ay ah-PAR-ens), which means “apparent being” or “the state of appearing.”

What does this mean? Auriol said that when you see something, your mind creates a kind of copy of it. But here’s the weird part: he didn’t think this copy was separate from the real thing. He thought it was the real thing—just existing in a different way. The trees-on-the-boat-bank that appear to be moving? Those are the real trees, but they’ve been put into “apparent existence” by your eyes. The circle that appears when you twirl the pencil? That is the pencil, but in its “apparent” form.

For Auriol, then, every act of perception—seeing, hearing, touching, even thinking—involves taking something real and putting it into this special state of “appearing.” Your mind doesn’t just look at the world. It transforms the world it looks at, by making it appear.

This is a genuinely strange idea. Most of us assume that when we see a tree, there’s (1) the tree out there, and (2) our mental image of the tree in here, and those are two different things. Auriol said no. They’re the same thing, just in two different modes of existence. The tree has real existence in the world, but it also has “apparent existence” in your mind. And when you’re looking at it correctly (not hallucinating, not dreaming), these two existences match up perfectly—they’re the same tree, you just don’t notice the difference.

Wait, That Sounds Like Hallucinations

Exactly. And that’s the problem Auriol’s critics had with his idea. If your mind is always “putting things into apparent existence,” and if sometimes it does this without the real object being present (like when you dream, or hallucinate, or see the afterimage of a bright light), then how can you ever be sure you’re perceiving something real? How do you know you’re not always just seeing the “apparent” version?

Auriol’s answer was kind of unsatisfying to his critics. He said that normally, under good conditions, your God-given senses work correctly. When they’re working right, the “apparent existence” and the “real existence” line up. You can tell the difference between a real perception and an illusion mostly because… well, it mostly works. He didn’t really explain how you know when it’s working. He just assumed it does.

This made other philosophers nervous. If your theory of perception can’t clearly explain how to tell reality from illusion, you’ve got a problem. Auriol seemed to think the problem didn’t matter much—he was what philosophers call a “reliabilist,” meaning he thought your cognitive faculties are basically reliable unless something goes wrong. But not everyone was so relaxed about it.

What About Thinking?

Auriol didn’t just apply his “apparent existence” idea to seeing and hearing. He applied it to thinking, too. And this is where his idea gets even stranger and more interesting.

You might think that when you think about, say, “horses in general,” you’re thinking about a concept—an idea of “horseness” that exists in your mind. Auriol agreed that concepts exist in the mind. But he insisted that your concept of a horse is the actual horse (or horses) you’ve encountered, just transformed into a different kind of existence. The concept isn’t a picture of the horse. It’s the horse itself, appearing to you intellectually.

This leads to a pretty radical conclusion. When you think about “human being” after meeting Socrates and Plato, you’re not thinking about some abstract idea floating in your head. You’re thinking about Socrates and Plato themselves—but in a special “apparent” form that lets you ignore their differences and focus on what they share.

For Auriol, this solved a bunch of problems that had bothered other philosophers. How can one concept (like “human”) apply to many different people? Because the concept is all of those people, apprehended in a way that shows them as similar. How can you have certain, scientific knowledge about “all humans” when you’ve only met a few? Because when you think “human,” you’re thinking about every human you’ve ever encountered, rolled together into one apparent object.

The Big Split: Seeing vs. Imagining

Auriol made another distinction that mattered to him a lot: the difference between “intuitive” cognition and “abstractive” cognition.

“Intuitive” cognition is like seeing something right in front of you. It feels direct, immediate, present. You don’t have to think about it—the thing is just there. The object appears as existing, as real, as now.

“Abstractive” cognition is like imagining something. When you picture a horse in your mind, you know it’s not really there. The horse you’re imagining doesn’t feel present or immediate. It’s abstracted away from actual existence.

Here’s the thing that made Auriol different from other philosophers of his time. Most said that intuitive cognition only happens when the object is actually present and real. If you have an intuitive vision of something, then that thing must exist. But Auriol disagreed. He pointed to afterimages and dreams: when you see a ghostly sun after looking at the real one, that’s still an intuitive cognition—it feels present and real—even though the sun isn’t there anymore. When you dream of a monster, it feels present and immediate, even though it’s not real.

So for Auriol, you could have intuitive cognition of things that don’t exist. The difference between intuitive and abstractive wasn’t about whether the object was real. It was about the feel of the cognition itself—whether it seemed direct and present, or indirect and absent.

But then Auriol dropped a bombshell. He said that human beings, in this life, never have intuitive intellectual cognition. We only have abstractive intellectual cognition. What does that mean? It means we can never directly see reality with our minds. We only reason about it indirectly, piecing things together from our senses and our imaginations. We can think about things, but we can’t intuit them.

Angels and the souls of the blessed in heaven have intuitive intellectual cognition—they can directly “see” reality with their minds. But we can’t. We’re stuck with abstractive reasoning, always at one remove from the real world.

So How Much Can We Really Know?

This led Auriol to a surprisingly humble view of human knowledge. He said there are some questions we just can’t answer with our own reason. For example: Has the universe always existed, or was it created at a specific moment in time? Auriol said we can’t prove either one. We might believe (as he did, as a Christian) that the universe was created by God. But we can’t demonstrate it philosophically. Our minds just aren’t capable of that kind of direct insight.

He thought this was because to answer that question, you’d need to have direct intellectual cognition of something like “temporal instants”—the basic building blocks of time. And we just don’t have that. We reason about time, but we don’t directly perceive its nature.

This is a pretty striking conclusion for a philosopher to reach: that human reason has limits, and those limits are real and absolute, not just temporary. There are things we will never figure out by thinking alone, because our minds are built in a way that prevents it.

Why Bother With All This?

You might be wondering: why does any of this matter? Why should a 12-year-old care about what a French monk thought in 1318?

Here’s one reason. The question Auriol was wrestling with—the gap between appearance and reality—is still alive today. When you put on a VR headset and see a world that isn’t there, you’re dealing with Auriol’s problem. When you wonder whether an AI can truly “see” or just process data, you’re dealing with Auriol’s problem. When you wake up from a dream and feel confused about what’s real, you’re dealing with Auriol’s problem.

And here’s another reason. Auriol’s idea that the mind is active—that it doesn’t just receive the world, but transforms it—was way ahead of its time. Many philosophers today think something similar: that your brain is constantly constructing your experience, not just recording it. The colors you see aren’t “in” the objects; your brain makes them up. The sounds you hear aren’t “in” the air; your brain interprets vibrations. We live in a world of appearances that our own minds have built.

But Auriol also offers a warning. If the mind is always transforming reality into appearances, how do you know when you’re seeing things clearly? His answer was basically: you don’t, not for sure. You just trust that under normal conditions, things work. That’s not the most satisfying answer in the world. But it might be the most honest one.

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Key Terms

Term	What it does in Auriol’s theory
Esse apparens	The special “apparent existence” that objects take on when they are perceived or thought about
Intuitive cognition	A way of perceiving where the object feels directly present and real (like seeing something in front of you)
Abstractive cognition	A way of knowing where the object feels absent or indirect (like imagining something in your head)
Ratio (plural: rationes)	A basic feature or aspect of an individual thing that the mind can grasp to form a concept; each individual has several
Maximal similarity	The idea that the same feature in different individuals (like Socrates’ “rationality” and Plato’s) is not identical, but as similar as two things can possibly be
Conceptualism	The view that only individual things really exist in the world; universals (“human,” “animal,” “red”) are only in the mind

Key People

• Peter Auriol (c. 1280–1322) — A French Franciscan monk and philosopher who argued that perception involves putting objects into “apparent existence,” and that human beings (in this life) can only have abstractive intellectual cognition.
• John Duns Scotus (c. 1266–1308) — A Scottish philosopher who introduced the distinction between intuitive and abstractive cognition; Auriol rejected his view that intuitive cognition requires the object to be actually present and existing.
• William Ockham (c. 1287–1347) — A later philosopher who was influenced by some of Auriol’s ideas but rejected others; he argued that we can have intuitive cognition of things that don’t exist, and also that the human intellect can have intuitive cognition in this life.

Things to Think About

1. If your senses can be fooled by illusions (like the twirling pencil or the afterimage), does that mean you can never be completely sure that any perception is real? Or is there some way to tell?

2. Auriol thought that concepts are the things they represent, just in a different form. Is that weird? What would it mean for your concept of “your best friend” to actually be your best friend, mentally transformed?

3. If human beings can never have direct intuitive intellectual knowledge (only indirect abstractive knowledge), what does that mean for big questions like “Does God exist?” or “Is there life after death?” Can we ever really know the answer, or do we just have to decide what to believe?

4. Auriol’s critics worried that his theory made it too hard to tell reality from illusion. Is that a fair criticism? Or is it actually more honest to admit that there’s always a gap between how things appear and how they really are?

Where This Shows Up

• Virtual reality and video games raise the same question Auriol asked: when your brain is fed a convincing illusion, what counts as “real” experience?
• Dream research explores how and why dreams feel real while we’re in them—exactly the kind of thing Auriol used as evidence for his theory.
• Cognitive science and neuroscience study how the brain actively constructs perception rather than passively recording it, which is very close to what Auriol argued 700 years ago.
• Skepticism—the philosophical view that we might not know as much as we think we do—is still a live debate, and Auriol’s work is part of its history.