The doppelgänger and the dead God in Jean Paul’s Jacobian critique of Fichte

German idealism is defined partly as a response to Jacobi's master argument that, given its commitment to the principle of sufficient reason, philosophy is committed to nihilism – to the annihilation of individuals as sources of freedom and purposiveness. Jacobi's master argument provokes sustained engagement from Fichte, who deduces logical laws, including the PSR, from reason or the I as philosophy's first principle. It is well known that Fichte's defense of freedom and purposiveness against annihilation does not satisfy Jacobi, whose 1799 open letter to him coins ‘nihilism' to name Spinozism and its inversion, the Wissenschaftslehre. It is less well known that Fichte's defense provokes a satirical critique from Jacobi's most devoted acolyte, the German romantic author Jean Paul. This neglect is significant not only because Jean Paul's critique is recognizably Jacobian, but also because it incorporates his two neologisms: ‘doppelgänger' and ‘God is dead'. In this paper, I rehearse Jacobi's master argument and Fichte's response to it. I then provide an account of Jean Paul's neologisms and show how they figure in his charge of nihilism against Fichte. Finally, I reconstruct and defend Fichte's rebuttal of Jean Paul’s Jacobian critique.