Did Your Mind Invent the Laws of Nature?
The Scientist’s Secret Recipe
In 1871, a fierce debate gripped German philosophy. Could we trust space and time as they really are, or were they just shapes our minds impose on things? A young scholar named Hermann Cohen (1842–1918) stepped into the fight. He had grown up in Coswig, Germany, the son of a synagogue cantor. He even left high school to study at a rabbinical seminary before turning to philosophy. Now he argued that the whole debate had missed the point.
Cohen believed that the most important ideas of Immanuel Kant had been badly misunderstood. Many thinkers at the time said that knowledge came from two sources: objects in the outside world that knock on our senses, and structures inside our own heads — space, time, the categories — that organize the noise. On that view, the mind’s structures were subjective mental goggles. The only truly objective part of knowledge came from the objects themselves.
Cohen thought this picture was completely wrong. He insisted that Kant’s a priori laws — the rules we don’t learn from experience — are not mental goggles at all. They are the fundamental principles of mathematics and the basic laws of physical science, like those of mechanics. These laws, Cohen said, are what make any object of experience possible for us in the first place. They are objective because they are necessary for science. So philosophy doesn’t need to peek inside the scientist’s brain. It needs to study the methods by which science represents objects.
This led Cohen and his students to what they called the transcendental method. Philosophy starts by accepting the best scientific theories of the day as a fact of science — something given, like a finished textbook. The philosopher’s task is not to doubt that physics gives us genuine knowledge. It is to dig into those theories and uncover the hidden a priori principles that make that knowledge possible. For Cohen, doing philosophy is like being an engineer who takes apart a perfectly running machine to find its most basic gears.
Thinking Without Outside Help
Cohen didn’t stop there. In his later work, he took an even more radical step. He introduced the idea of pure thinking. Thinking is pure, he said, when it is free from any influence outside itself. No raw sense data, no mysterious gut feelings — nothing is allowed to just “be there” unexplained. Pure thinking generates the very rules that define what counts as an object for science. It is as if reason refuses to use pre‑cut bricks and insists on making every brick itself.
This was a sharp break from Kant. Kant had argued that human knowledge needs two separate sources: the understanding, which thinks concepts, and sensibility, which gives us raw sensations. Cohen threw sensibility overboard. Even space and time, he now argued, had to come from pure thinking. The shining example, for him, was the infinitesimal calculus. The tiny, endlessly divisible magnitudes known as infinitesimals are not things you can see or touch. They are pure creations of reason that allow physics to represent continuous motion and real objects.
Cohen’s unwavering rule — never accept anything as just given — had a name: methodological rationalism. It isn’t the belief that we’re born with a ready‑made list of truths. It’s a relentless demand to search for reasons. Every time a concept looks like it simply fell from the sky, Cohen would ask why it must be this way until no brute fact remained.
From Laws of Nature to Laws of Right and Wrong
Cohen believed the transcendental method could be used for any area where we have real knowledge. So he turned it on ethics — the study of how we ought to act. Instead of starting from feelings or divine commands, he started from the “fact” of jurisprudence, the science of law. Pure jurisprudence, for Cohen, investigates the very idea of a universal law that binds human beings, not just the laws of one country.
He noticed a deep tension inside the concept of humanity. Each of us is a unique individual, but we are also members of groups — families, economic classes, religious communities. Our wills often clash. How can we reconcile one person’s choices with everyone else’s, so that we can all live together fairly? Cohen’s answer was that we need universal ethical laws — rules that could unify all our wills into a single, coherent whole. He imagined an ideal state whose laws are the result of an unending process of public reasoning, where every voice demands and gives reasons.
This led Cohen to support democratic socialism. He argued that a state that truly reconciles individual wills must have universal suffrage — every adult gets to vote. He also believed that ideal laws would allow workers to own the means of production collectively, because treating someone only as a tool for profit violates the core idea of respecting every person. In late‑19th‑century Germany, where wealthy men had more voting power than everyone else, these ideas were both philosophical and politically brave.
When Reason Builds a Bridge to God
Cohen also wanted to understand religion’s place. He had already defined God, in his ethics, as the ideal of perfect ethical laws joined with the faith that humanity would eventually realize them. That seemed to leave no separate job for religion. Yet Cohen insisted religion has its own vital role, without making his ethics incomplete.
His key move was to notice that systematic ethics deals with people as members of humanity in general — as citizens bound by the same laws. But it doesn’t talk about your personal moral failings, the ones you’re ashamed to admit even to yourself. Religion, Cohen thought, is exactly about that: the individual facing their own sins. He used the language of “I” and “Thou.” When you recognize another person as a Thou — a unique individual with a specific moral struggle — you relate to them differently than when you treat them as just another generic human.
Most importantly, you have to recognize yourself as a Thou. You discover your true moral self, Cohen said, only when you study your own sin, admit it through confession, and strive to atone — to actually change. This striving creates a personal correlation between you and God. Because your sins are uniquely yours, your relationship with God becomes uniquely personal. Prayer gives you the strength to be honest with yourself; atonement turns your gaze toward the ethical ideals you want to live by.
Cohen believed that monotheism — the belief in one God for all humanity — was the historical source of this ethical vision. A single God for all people means all people are subject to the same moral law. For Cohen, Judaism was the original carrier of this insight, and he spent his last years showing how Jewish texts contain the deep structure of what he called a “religion of reason.” Scholars still disagree about whether his religion completes his ethics, breaks away from it, or simply stands beside it as a necessary partner. That live debate shows how rich his thinking remains.
Why Cohen Still Matters
Cohen died in 1918, but his fingerprints are everywhere in philosophy today. His anti‑psychologistic reading of Kant became the dominant way of understanding the Critique of Pure Reason — most scholars now agree it’s about the structure of knowledge, not brain science. His vision of philosophy as the historical reconstruction of scientific theories influenced thinkers from the logical positivists to Thomas Kuhn, who later described scientific revolutions.
More personally, Cohen leaves you with a big, unsettled question. If the laws of nature, moral rules, and even our picture of God are products of our own pure thinking, then what we build with reason really matters. The next time you argue about what’s fair, or wonder why a math formula works so beautifully, you’re stepping into Cohen’s world — a world where reason doesn’t just discover truth, but actively creates it.
Think about it
- If the laws of physics come from our own thinking, could future generations with different ideas change what counts as a law of nature?
- If everyone’s reason leads them to different moral rules, is there a way to test which rules are truly universal — or is the idea of universal ethics just an ideal we can never fully agree on?
- If God is the ideal of perfect ethical laws, does praying to God feel like talking to something beyond you, or like talking to your own best self?
