Perception is any content I am aware of. It's not a physical object, but still it occupies my consciousness. Due to lack of knowledge in the field of consciousness (Despite all rumours, consciousness hasn't been explained) it's hard to say in precise terms what kind of object a perception is.
Introspectively, everybody has come to have a perception, not one, but billions. The bell of the church, the image of my hands typing this words on the keyboard, a feeling of worry that the rain will not stop, and so on. In what, I experienced as one of the most challenging chapter of the Philosophy of Freedom (chapter IV), we encounter three conceptions about perception.
The most basic is the naive conception which says:
In my perceptions, the reality is given to me. I grasp the world as it is.
The objections to this conception have given counterexamples that show one can have very different perceptions about the same thing, that contradict themselves. Think at the scientists from the ancient times. They believed the Earth is the center of the world, and the Sun moves around it. That's how they perceived the things from down here. Copernicus had a very different perception (I'm not very familiar with how he made this discovery), but the truth is nowadays we can have the perception which shows the Earth moving around the Sun. etc.
The second one is the Berkley-conception or subjective-idealism or immaterialism. This is a strange and thought-provoking conception. This conception says that what we perceive does not have a real existence. And it's not, as we'll see, because our sensory-systems are defective that this thing is happening, but it is because there aren't things out-there that we could perceive. The world has no existence. This Englishman with weird ways of seeing the world says and beliefs that only spirits exist and those spirits are creating these perceptions in their heads, they generate all the time perceptual-content. Or, he accepts, the Divine Being itself might be adding this content in these many consciousness.
Moving forward to the kantian conception.This conception does not agree with the Berkley conception, in one respect: the non existence of the world. According to the kantian conception there is a world, there are objects, beings, substances, etc. But the thing (the sad thing) is we can not grasp the real world.
Due to the latest discoveries from physics, psychology and physiology, a belief in the imperfection of our senses has been adopted by many scientists and people. The three sciences mentioned have showed all kinds of cases where human beings were having abnormal perceptions. Someone could not see colors. A cured blind man declared he had very different ideas derived from his tactile perceptions about the objects around him, than the ones he got from his visual perceptions. Even Rudolf Steiner gives us reasons to worry and doubt. He shows our sensible perceptions are dependent on the place we are. The trees from the end of the alley look much shorter when I'm far away from them, then they look when I'm right next to them. But then even the sensory organs are faulty. We don't see the world. We grasp only what this perceptions-systems generate in our consciousness.
The Kantians make all kind of speculations about how the perceptive-process functions. Right from the start, they say, the perception-organ modifies the outer element, the real element with which it interacts, and than the chain of nerves, transmitters and even the central nervous system don't stop from changing the changed real element again and again. In the end the brain is causing individual sensations to appear in the soul, the soul takes all that and projects it over the objects outside.
The falling of this baroque edifice of arguments is produced by the simple reflection of Rudolf Steiner, the healer of the mind and the Savior of reality.
Rudolf Steiner points to a very elementary fact. The Kantians talk about all those things as if they had a privileged access to the reality, as if their perceptive-organs were not like everybody else. They talk so sure about what is going on in our eyes and how this faulty eyes of ours deform what the reality is trying to show to them and than they continue talking like this about our brain, our nerves and even about the interaction of the brain with the soul, and in all this talk they forget all the time that they are not different, they are like everybody else. So what they perceive as being the eye, the nerves, the brain, the soul, etc.. all of them are just the result, the fabrication of their own faulty system of perceptions, just illusions.
Their conception fails because it undermines itself.
