Six years later, Magee tried again, and that time he loved Schopenhauer. One of the first things he actually says about Schopenhauer's ideas, on page 356, is:
Schopenhauer believed, along with a great many other people then and since, that Kant's most important insight was that what we human beings can think, perceive, know, experience, or be aware of in any way at all depends not only on what the reality is with which we have to deal but also on the apparatus we have for doing those things -- our human bodies with their senses, nervous systems and brains.From this I have concluded that Schopenhauer is worthless (which I already suspected). It also confirms that Kant is worthless. Why?
First, this idea does not have the ring of great philosophy. It's not a penetrating insight. It's a lot closer to common sense. There's just nothing special about it. It seems to me that this idea must have been invented by countless people, most of whom didn't consider it worth making a fuss over. If this is the best Kant has to offer, then he is simply not a great philosopher. Even if it were true it would not be very impressive.
There is a major school of thought which existed before Kant, and which believes we gain knowledge of the world through our senses. Is it really the case that none of them ever considered the limitations of our sense organs before Kant pointed it out? That is not plausible. They must have considered the issue and had a reply already worked out.
Now for the critical flaw: Kant's "most important insight" is false.
As Popper taught us, starting points are not very important, what's important is to look for and correct errors. If you begin with limited and flawed ideas, so what? All our ideas are flawed anyway, and all our ideas are limited in their scope and understanding. That doesn't stop us making progress. Learning takes as input flawed and limited ideas, then proceeds to flawed and limited criticisms of them, and flawed and limited guesses at new ideas, and flawed and limited suggestions for minor changes to existing ideas, and outputs an unlimited stream of progress.
If your eyes are faulty that is not a fundamental handicap. You can get glasses or a microscope. You can ask questions of people with better eyesight. You can touch things to get a more accurate idea of their size. You can get a seeing eye dog. Or you can guess in what way your eyes are faulty, then reinterpret everything you see to account for the fault. And then you can see what goes right and what goes wrong, and adjust your way of reinterpreting. Even Hellen Keller was able to learn things.
No one's senses are perfectly reliable, and that isn't important.
One final issue is universality. There is some set of sense organs, which is fairly minimal, which allows one to do any measurement possible (with appropriate tools and aids, which you can construct). For example, only having the sense of touch would be sufficient to learn anything. You can construct artificial eyes which output braille. And a sound recorder that outputs braille. And a smeller and taster, and more. And therefore Kant's implication that we are limited in what we can measure/observe by the details of our sense organs is false. Even Hellen Keller had a universal set of sense organs.
Similar lines of argument apply to our nervous systems and brains which have universality, taking into account possible augmentations which we are capable of performing (after learning how to perform them, which we are also capable of).
All in all, it's not really a bad idea. If my neighbor told it to me, I'd give him some pointers and encourage him to think about it more. It's not obvious why it's false. But it's not great philosophy either.