Prolegomena to Any Future Metaphysics

Prolegomena to Any Future Metaphysics is a work of scientific philosophy by Immanuel Kant. First published in 1783, Prolegomena explores whether metaphysics is possible, and how it works if it exists at all. It’s a polemic work, meaning it is a rhetorical book that undermines opposing arguments to justify its own position. This was a popular writing style with academics in the 18th century. Kant was a German philosopher best known for his first work, the Critique of Pure Reason, and his theories on morality. He is one of the most respected philosophers from the Age of Enlightenment.

In Prolegomena, Kant questions whether metaphysics is a real science. He begins by asking questions of metaphysics before exploring three major transcendental problems. After exploring these issues, Kant argues that, although metaphysics isn’t a science yet, it’s possible to make it a science by ascribing rules to it.

In the first section, “Preamble on the special features of all metaphysical knowledge,” Kant argues that there are two types of knowledge—a priori and a posteriori. A priori knowledge comes from outside our own experience. A posteriori knowledge, on the other hand, comes from our own experiences. Mathematics is a priori because we can understand it without experiencing it for ourselves.



Metaphysics is the a priori study of what we can never personally experience. When we study metaphysics, we’re attempting to make sense of the unknowable. More importantly, it’s impossible to devise any scientific rules for studying metaphysics, because scientists can’t agree on what “makes” a metaphysical argument.

A science, or a discipline, exists because we can classify and define it. Mathematics is an example. We can study mathematics at school and learn addition, subtraction, and so on. We understand that mathematics is possible, even if we don’t understand why it exists. However, since we can’t classify metaphysics at all, we’re forced to question whether it exists in the first place. Until we decide whether it’s possible, we can’t begin to understand how it works.

Kant suggests a possible solution to this conundrum—pure mathematics. Pure mathematics is a combination of reason and experience. Reason shows us that some mathematical rules exist. We also collectively agree that other rules exist, even if we haven’t experienced them for ourselves. Pure mathematics is a hybrid between “synthetic” and “analytic” a priori thought. If we can show that metaphysics is also a hybrid, then we can accept it as a science.



Kant raises three transcendental questions to prove that pure mathematics exists as he claims. If he can prove that pure mathematics is possible, then he proves that metaphysics is impossible unless we view it differently. He asks, firstly, why pure mathematics exists. Secondly, he asks if pure science can also exist. Thirdly, he questions what pure science means for metaphysics and its future.

In “Main transcendental Problem 1: How is pure mathematics possible?” Kant argues that it’s possible to understand geometry, and spatial relations, a priori. This is because things exist regardless of whether we perceive them or not. We understand that space and time exist outside our individual experiences, and we experience these things intuitively. The same can be said for pure mathematics.

“Main transcendental Problem 2: How is pure natural science possible?” explains why nature is a science. We’ve made nature a science by applying universal laws to the natural world. Our experience isn’t absolute, because it’s relative to the individual, but we can still agree on basic facts. For example, we can agree that the sun makes us feel warm, but we’re not all hot at the same time. Although we can argue about whether it’s hot or not, we know that the concept exists. Our faculties of understanding permit us to understand the natural world, combined with our intuition.



In the final section, “Main transcendental problem 3: How is metaphysics possible in general?” Kant applies his findings from problems 1 and 2 to answer the metaphysics problem. Metaphysics is purely rational. We can’t use our experience to answer the questions, and so we rely on our ability to reason. For example, we don’t know the truth about God, but there’s no way to agree on God, and so we use our own faculties to define God for ourselves.

Metaphysics can’t possibly be a science unless we change how science is defined. What we can accept is that metaphysics makes us think about the world and how it operates, even if we never arrive at a conclusion. For example, we think about God, but since no one has experienced God, there’s no way to know who is right and who is wrong. Just because we can’t reach a conclusion, however, doesn’t mean that we should undermine metaphysical thought.

Just as science disproves itself all the time, it’s possible that metaphysics simply teaches us that there’s something unknowable in the universe, and there’s a limit to the human psyche. The idea that knowledge is self-limiting is its own rule, and perhaps this rule can underpin metaphysics as a science.