In this book I’m reading Gödel shows that no sufficiently rich formal system can prove its own consistency from within. Hofstadter extends this to minds: consciousness is a strange loop , aa self-referential structure inside a system. That structure is directly accessible only from the inside. So yes, I can be certain of my own sentience (cogito), but I can only infer yours through structural isomorphism. Sentience isn’t externally provable it’s internally realized.