In order not to suggest the idea of substratum that contains within itself this power of acting, I do not even want to call the "I" an acting something [ ein Handelndes ].
-- Some have raised the objection 9among others) that the Wissenschaftalehre grounds philosophy in an "I", conceived of as a substratum that exists independently of the "I"'s activity ( an "I" as a thing-in-itself).
But how could one argue in this way, since the derivation of ANY substratum from the "I" 's necessary mode of acting is distinctive of that mode of acting and especially suited to it?
I can say perfectly well how certain people could and had to argue in this way.
These people CANNOT begin anything at all WITHOUT a substratum, because they are UNABLE to raise themselves from the point of view of common experience to the point of philosophy.
Accordingly, they supplied the Wissenschaftslehre with the idea of a substratum, which they themselves brought out of their own reserves, and then they chastised the Wissenschaftslehre for their own incompetence;
moreover, they chastised it, not because they themselves had seen the error of conceiving of the "I" as a substratum, but because Kant REJECTS such a substratum of the "I".
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the subject as essentially self-positing. The subject is not a thing, or substance, but rather something that constitutes itself through its OWN self-reflecive, conscious acts.