Kant believes one cannot obtain a representation of space (RS) empirically because, without a priori RS, one cannot distinguish between sensations triggered by inner and outer stimuli. Perceiving outer objects necessitates a priori RS for containing and separating them. One can imagine no objects but never no space. If a mind does not assume there is space, it cannot perceive outer things because it assumes no distinction between what is inside or outside itself and where external things are; the chair would not have been seen for us to acquire RS. Thus, RS is a priori.
Some people may object that how Kant argues that RS is a priori that applies to argue that other sensations are a priori. For example, one needs an ideal representation of colors to perceive colors in external objects. However, many believe representations of colors are acquired empirically. The truthfulness of such arguments similar to Kant’s RS argument is highly questionable, so fundamental flaws may exist in it.
A defender of Kant’s RS argument can say that Kant is not overreaching. Kant’s RS argument is limited to justifying that RS is necessarily assumed by the mind for perceivers to experience any sensations as outside of themselves. If an argument about the origin of one’s ability to identify representations of characteristics of external things like color models after the RS argument, it is unfit. Such representations are about how objects are distinct amongst themselves to the perceiver. Kant will say one’s mind does not necessitate a priori representations of all characteristics in external objects to perceive these characteristics, but one’s mind definitely needs RS a priori to sense the existence of these external objects and some of their characteristics at all (e.g. separate from the perceiver).
Even if Kant is right, his RS argument does not prove anything about the world beyond human perception, which is a black box and unknowable. A priori RS indicates that one’s perception towards the empirical world is fundamentally biased because the mind has assumed how the empirical world works since the beginning of the perceiver’s life. This proves the inability of any human perceiver to perceive the complete nature of the objects without subjective interpretation. We can only perceive this object based on how this object affects our senses, which are interpreted based on the ideals of the mind like RS. Therefore, Kant’s RS argument simply proves something about us, not about the world.
That RS is a priori implies that when people propose philosophical questions regarding the external reality, the answers we have are always based on our mental interpretations, which are fundamentally subjective and biased, not the full truth. There are questions that human philosophy cannot answer because we cannot perceive external things completely and truthfully.
You can also read:
Every Moment Is A Choice – The Story Of Edith Eger, A Survivor In Concentration Camp