Unfortunately, I don't think the author correctly describes the philosophy, which is going to make it harder to understand. Here's what he says:
The basic question for all these thinkers is whether the patterns we see in the world around us really reflect patterns that exist in nature or are simply attempts by our minds to structure what we see. For many German philosophers, a key effort was to understand the principles governing societies.Kant is described as giving an account by which nothing happens except through law, and indeed he does say that in the Groundwork. However, Kant's already talking about the world as understood within the mind. What Kant argues in his first critique is that we can't understand the world as it really is, but only as it appears to us, at which it is already being filtered through what he called a "transcendental apperception." For example, your mind takes sound waves and light waves and a sensation of gravity and tactile sensations, and these are all coming in from different organs on different nerves. But it presents you a picture of a soccer game in which you are participating. Is there really a soccer game? You can't know that even in principle. You can only know about the appearances in the mind.
This is a particular issue for economists, who seek patterns in the mass of statistics coming out of stock markets and labor surveys. It's not always enough, though, to look at how markets and prices behave and describe the mathematical patterns they seem to follow. In practice, there always seem to be exceptions to the rules, sometimes catastrophic ones, which suggest that those maybe patterns have more to do with our minds than the natural world itself.
"Anglo-Saxon economists are guided by the utilitarian philosophy of John Stuart Mill or Jeremy Bentham, asking merely if a policy works," The Economist recently wrote. "Germans side with Immanuel Kant, believing that nothing works except through law, and are horrified when the [European Central Bank] strays from its narrow mandate."
There is some truth to this position, as is made clear by the example of the banana. If the body were simply a physical instrument, such that the eyes were merely receiving light waves which were merely translated into images by the brain, bananas would change color with changing light conditions like other things do. That's the way this article from LiveScience describes the process, and it's what would be true if the process works the way they think it does: if the body was a machine, so to speak.
In fact, under any natural lighting condition, your mind will report it to you as banana yellow.
What color is a banana? A banana is yellow in the sunlight and in the moonlight. It is yellow on a sunny day, on a cloudy day, on a rainy day. It is yellow at dawn and at dusk. The color of the banana appears constant to the human eye under all these conditions, despite the fact that the actual wavelengths of the light reflected by the surface of the banana under these varied conditions are different. Objectively, they are not the same color all the time. However, the human eye and color recognition system can compensate for these varied conditions because they all occurred during the course of the evolution of the human vision system, and can perceive the objectively varied colors as constantly yellow.So the law we infer -- "if it is a banana, then it is yellow" -- is actually not a product of the world, but a product of the mind. The evolved mind is coloring the fruit in a lawlike way. Once we move to kinds of lighting that our eyes didn't evolve to see, the law turns out not to be real. It was only a product of our minds.
So a banana looks yellow under all conditions, except in a parking lot at night. Under the sodium vapor lights commonly used to illuminate parking lots, a banana does not appear natural yellow. This is because the sodium vapor lights did not exist in the ancestral environment, during the course of the evolution of the human vision system, and the visual cortex is therefore incapable of compensating for them.
Now, the first thing you'll notice is that Kant isn't quite right: we have just managed to learn something about the thing itself, the thing outside of our minds. And we've managed to find, through science, an example of a place in which the apparent laws are products of the mind and not of the thing. There's this huge division in German philosophy since Kant, between those who think that lawlike ideas are real (Hegel) and those who think that ideas about the world are often totally unreliable (Wittgenstein). The science gives us a middle way.
Greek philosophy, being much older, believes the laws are in the things, and the things are real. If you kick a ball something different will happen than if you kick a dog, and the reason for the difference is that the ball and the dog have different natures. The things are different, and their natural or essential differences will produce different results.
That's more like the scientific position, oddly enough, than the Modern position is. It's why we can say that bananas aren't "really" yellow the way we think they are: we look at the thing, find out what wavelengths of light its skin are reflecting, and then see that our eyes are treating those wavelengths differently in some cases than in banana cases. Thus, we say (as the Greeks) that the nature of the banana produces skin that reflects light of a certain wavelength, but that it's our nature -- our evolved nature -- that makes us see a favored food source as brightly outlined in all the lighting conditions our ancestors would experience. Both are lawlike: the banana's genetics reliably produces skin of a certain kind, and our evolved nature reliably produces minds of a certain kind. The important question for answering the German problem is figuring out where the law is.