(Even the attribution of the idea to Descartes seems wrong to me: Cogito ergo sum is not the first step in the Cartesian reconstruction, it is the second. The first is Dubito ergo cogito. The starting point of the reconstruction is not a hypothetical a priori that is immediate to the experience of existing as a subject. It’s a rationalistic a posteriori reflection on the first stage of the process in which Descartes had articulated a state of doubt:
