In 1968 he published his two dissertations, Difference and Repetition (supervised by Gandillac) and Expressionism in Philosophy: Spinoza (supervised by Alquié).
Godine 1968. objavio je dve disertacije, Razlika i ponavljanje (pod nadzorom Gandilaka) i Ekspresionizam u filozofiji: Spinoza (pod nadzorom Alkuie).